-*- coding: UTF-8 -*-

README for sam2p
by pts@fazekas.hu
at Sun Dec 30 19:30:17 CET 2001 -- Fri Mar 22 19:25:03 CET 2002
Sat Apr 27 00:39:12 CEST 2002
Wed Jul  3 01:20:40 CEST 2002
Wed Feb  5 19:46:51 CET 2003
grammatical corrections by Steve Turner at Mon Jan 10 00:53:46 CET 2005

This is the README file for sam2p, a raster to PostScript/PDF image
conversion program. This file contains a 5-minute turbo tutorial for new and
impatient users (search for the phrase `Turbo tutorial' in your text editor).
As of now, this README file is the only, and definitive, documentation of sam2p.

sam2p is a UNIX command line utility written in C++ (C++98) that converts many
raster (bitmap) image formats into Adobe PostScript or PDF files and several
other formats. The images are not vectorized. sam2p gives full control to
the user to specify standards-compliance, compression, and bit depths. In
some cases sam2p can compress an image 100 times smaller than the PostScript
output of many other common image converters. sam2p provides ZIP, RLE and
LZW (de)compression filters even on Level1 PostScript devices.

Send donations to the author of sam2p:
https://flattr.com/submit/auto?user_id=pts&url=https://github.com/pts/sam2p

Do you need sam2p?

-- If you have a raster image (e.g. PNG, JPEG), and you need EPS or PDF output,
   then sam2p is probably very useful for you, because it can generate small
   EPS and PDF files quickly, outperforming many other
   tools (such as ImageMagick's convert) in speed and output file size. For
   EPS output files, the compatibility of sam2p is also better that of other
   tools.
-- If you use any of pdftex, pdflatex, luatex, lualatex, xetex or xelatex,
   and you have your raster images as PNG and JPEG files, then you don't need
   sam2p or any other raster image converter, because \includegraphics works
   on PNG and JPEG files directly.
-- If you want to make your JPEG files smaller, there are much better tools
   than sam2p for that.
-- If you want to make your PNG files smaller, you can use sam2p to convert
   PNG to PNG, but with other tools (such as pngout, advpng and zopflipng)
   you can get a better compression ratio at a cost of slower compression
   speed.
-- If you want to make your PDF files smaller, use pdfsizeopt
   (https://github.com/pts/pdfsizeopt). pdfsizeopt uses sam2p and other
   tools (such as jbig2) under the hood to make the raster images embedded
   in the PDF files smaller.

How small is the EPS output of sam2p?

-- A testimonial from Grant Ingram, UK: Anyway this is just a quick note to say
   thanks for writing the sam2p utility which I am using to create EPS figures
   of photographs for my thesis -- it works very well producing image sizes
   that are some 3% of the ones produced by ImageMagick.

-- A testimonial from Tom Schneider, US:

     -rw-------   1 toms     delila     88628 Mar  3 17:38 prototype-small.eps
     -rw-------   1 toms     delila   7979299 Feb 24 12:25 prototype.eps

   Good GRIEF you have written a nice program!!!!  The file is 90 fold
   smaller than the one from ImageMagick's convert.

   That image that was 90x smaller had been bugging me because it was so
   large that xdvi would strongly hesitate while I passed by the page.
   Now it just has a minor delay, thanks to you.

-- Results are not always that impressive. See the section
   {sam2p vs convert in 2017} for more details.

Benefits of sam2p:

-- sam2p produces much smaller output.
-- sam2p gives the user complete control over the data layout of the output
   image. This includes Compression, SampleFormat and TransferEncoding.
-- sam2p is fast.
-- sam2p doesn't depend on external libraries. (But it does depend on external
   programs for _reading_ JPEG, TIFF and PNG files.)
-- sam2p supports the mainstream image formats of today without compromise.
   sam2p has many file format fine-tuning features that are missing from
   most other converter utilities. For example:
   TIFF ZIP compression, TIFF LZW compression, TIFF
   JPEG compression, transparent PNG files, BMP RLE-4 and RLE-8
   compression, etc.
-- sam2p supports all levels (versions) of the PostScript language and
   output images have the smallest file size allowed by the LanguageLevel.
-- PostScript ZIP, RLE and LZW compression is provided for _all_
   LanguageLevels (!), even for PSL1 (which appeared in 1984). You can print
   your ZIP-compressed images onto your ancient printer of the 1980s.
-- sam2p supports all versions of PDF, and as with PostScript,
   output images have the smallest file size allowed by the version.
-- Output images of sam2p are always compliant to the standard selected by
   the user.
-- Output images of sam2p are real-world compatible, i.e the author has
   tested them with many common image processing programs, for example:
   Ghostscript, pdfTeX, xpdf, Acrobat Reader, The GIMP, ImageMagick, xv,
   Acrobat Distiller, QuarkXPress, InDesign. The author has also tested
   PostScript files on HP and OkiData printers.
-- sam2p converts every pixel faithfully, preserving all the 24 RGB bits
   intact. There is no quality or information loss unless you ask for it.
-- sam2p uses only a minimal number of libraries. You don't have to install
   33Mb of ballast software to use sam2p. Image libraries (libtiff etc.) are
   _not_ used, the math library is not used, libstdc++ is not used, zlib is
   not used.

Long-term limitations of sam2p:

-- Only DeviceRGB color space, with the Indexed, Gray and RGB image types.
-- Indexed images are limited to a maximum of 256 colors.
-- Alpha channel and transparency supported only for Indexed images: only
   one color may be transparent.
-- The entire input image is read into memory. During operation both the
   input and the output images may be held in memory.

Many thanks to Steve Turner for reviewing and making corrections to this
document.

Status
~~~~~~
sam2p is production-ready software. It is available from:

	https://github.com/pts/sam2p

The documentation is incomplete, but -- together with the examples -- it is
quite useful. Please have a look at the home page to find articles and more
documentation (the PDF docs are much more eye-pleasing than this README).
The source code contains valuable comments, but they may be hard to find
unless you're deeply into developing sam2p.

The author is developing sam2p in his free time. (He is studying and
working in non-free time.)

The imaging model is complete. Image output routines are stable and
adequate. Reasonable defaults are provided for all command line options.
sam2p can usually find the best SampleFormat automatically. There is
an educated (but not perfect) default guess for the Compression.

See subsection {OutputRule combinations} about all planned formats.

Turbo tutorial
~~~~~~~~~~~~~~
Quick compilation instructions:

1. Run: make
   It also runs ./configure with the right defaults for you.
2. Copy the `sam2p' executable to your $PATH, or invoke it as `./sam2p'.

Quick try:

-- ./sam2p examples/pts2.pbm try.eps
-- ./sam2p examples/pts2.pbm try.pdf
-- ./sam2p examples/pts2.pbm try.ps
-- ./sam2p examples/pts2.pbm try.png
-- ./sam2p examples/pts2.pbm try.tiff
-- ./sam2p examples/pts2.pbm try.xpm
-- ./sam2p examples/pts2.pbm try.bmp
-- ./sam2p examples/pts2.pbm try.jpg

A really short User's guide
"""""""""""""""""""""""""""
To convert an image, call:

	./sam2p <INPUT.IMG> <OUTPUT.IMG>
	Example: ./sam2p examples/pts2.pbm try.eps

To print an image as a full PostScript page, call:

	./sam2p [MARGIN-SPECS] <INPUT.IMG> ps: - | lpr
	Example: ./sam2p -m:1cm examples/pts2.pbm ps: - | lpr

To convert an image to be included as EPS (Encapsulated PostScript) into
(La)TeX documents, call:

	./sam2p <INPUT.IMG> <OUTPUT.eps>
	Example: ./sam2p examples/pts2.pbm test.eps
	In file.tex: \usepackage{graphicx} ... \includegraphics{test}

To convert an image to be included as PDF into pdf(La)TeX documents, call:

	./sam2p <INPUT.IMG> <OUTPUT.pdf>
	Example: ./sam2p examples/pts2.pbm test.pdf
	In file.tex: \usepackage{graphicx} ... \includegraphics{test}

If you have a large image file (possibly originating from dumb software),
you can reduce the image size and keep the same filename. (Please note that
some meta-information may be lost using this method.) This operation is
_DANGEROUS_ if you don't have a backup, because due to a software or
hardware problem, sam2p might clobber time image file so the actual image
gets lost. To overwrite a file in-place, call:

	./sam2p <INPUT-OUTPUT.IMG> --
	Example: ./sam2p test.tiff --

You may specify a compression method (or supply other command line options)
to make a file even smaller, call:

	./sam2p [OPTIONS] <INPUT.IMG> <OUTPUT.IMG>
	Example: ./sam2p -c:zip test.tiff test2.tiff

See the detailed documentation of available command-line options elsewhere
in this document. You may also read section {FAQ} for more information.

Too see a list about the supported input and output image file formats, call:

	./sam2p

Example output:

	This is sam2p v0.39.
	Available Loaders: JAI PNG JPEG TIFF PNM BMP GIF LBM XPM PCX TGA.
	Available Appliers: XWD Meta Empty BMP PNG TIFF6 TIFF6-JAI JPEG-JAI JPEG PNM GIF89a XPM PSL1C PSL23+PDF PDF-JAI PSL2-JAI l1fa85g P-TrOpBb.
	Usage: [...]

The list of ``Available Loaders'' lists the input image file formats. All
except for JAI are self-explanatory. JAI is JPEG-as-is, it means reading a
JPEG file and writing back the exactly same image into an other JPEG variant,
without quality loss.

From the list of ``Available Appliers'' one can derive the supported output
image file formats. XWD, BMP, PNG, TIFF6, JPEG, PNM, GIF89a and XPM are
self-explanatory. TIFF6-JAI, JPEG-JAI, PDF-JAI and PSL2-JAI are JPEG
variants into which JAI files (see above) can be saved. While the names of
the remaining appliers may be quite cryptic to the beginner user; most of
those appliers provide sam2p's excellent support for writing PS, EPS and
PDF files.

sam2p operation modes
~~~~~~~~~~~~~~~~~~~~~
sam2p is a command line utility (i.e, without a graphical user
interface), so it can be used by composing a command line with the
appropriate options and parameters, and launching it. See sections ``Turbo
tutorial'' and ``One-liner mode'' for more details.

sam2p is not interactive, it doesn't ask questions; thus it is completely
suitable for batch processing and automation. sam2p doesn't log errors, but
its STDERR can be redirected to a log file quite easily.

There are three modes sam2p can operate in:

-- one-liner mode: (since sam2p 0.37)
   the user, perhaps, has to type a long command line, specifying the input
   and the output file name, output file format, compression options, etc.
   Most of the functionality of sam2p is available in a quite intuitive way
   in one-liner mode. Users of the `convert' utility from ImageMagick and
   `tiff2ps' and `tiffcp' will find that one-liner mode of sam2p is very
   similar to them. This mode is recommended for impatient users.

   Due to the nature of sam2p development, some new functionality of job mode
   might be missing from one-liner mode. Please report this as a bug.

-- job mode: the user has to write a ``job'' file (recommended extension:
   .job), which specifies all conversion parameters, including the input and
   output file name. The name of the job file must be passed to sam2p. This
   mode is recommended for expert users who want to retain full control of
   all aspects of the final output. All functionality is available in job
   mode. This is especially useful in repetative but time separated jobs.

-- GUI mode: This is completely experimental, and will be very probably
   dropped in the near future. Try executing sam2p.tk (TCL/Tk is required).
   Please don't use GUI mode, use one-liner mode instead! The flexability
   of a one-liner (or job) mode is nearly imposible to encompas in a GUI.
   No more documentation is provided for GUI mode.

   There might be a Micro$oft Windoze version of sam2p available in the near
   future, but very probably you won't get real GUI with radio boxes, lists
   and file selection dialogs. You'll have to start sam2p from the DOS
   prompt...

One-liner mode
~~~~~~~~~~~~~~
This section contains a reference-style summary for the one-liner mode.
The author knows that this section is quite incomprehensible, and a bit old.
He is planning to completely rewrite it to be readable for the novice user.

The order of the arguments and options is significant.

Input file extension is discarded. The file format is recognised by its
magic number.

Output file extension gives a hint for /FileFormat:

.ps    :\
 .eps  :  \                        where PS: implies scale to fit page
 .epsi :   >  PSL1 PSLC PSL2 PSL3                     and
 .epsf :  /                             EPS: implies no scale changes
 [E]PS::/                               also see Q9 in FAQs below
.pdf   : \  PDF1.0 PDF1.2 (and)
  PDF: : /    PDFB1.0 PDFB1.2
.gif   : GIF89a
.pnm   : PNM (for use with transparency)
.pbm   : PNM /SampleFormat/Gray1
.pgm   : PNM /SampleFormat/Gray8
.ppm   : PNM /SampleForamt/Rgb8
.pam   : PAM
.pip   : PIP
.empty : Empty
.meta  : Meta
.jpeg  : JPEG
 .jpg  :  "
.tiff  : TIFF
 .tif  :  "
.png   : PNG
.xpm   : XPM
.bmp   : BMP /Compression/RLE
.rle   : BMP /Compression/RLE

Options (case insensitive):

-- --tmpremove {true|false} : remove temporary files after completion.
      Set to false for debugging.  Default: true.
-- -j -j:job   : display in-memory .job file
-- -j:warn     : be verbose and display warnings about impossible combinations in
                 the .job file
-- -j:quiet    : print only error and fatal error messages, suppress
                 warnings, notices etc. Must be put at the beginning of the
                 command line to suppress initial banners, too. For example,
                 `sam2p -j:quiet in.gif out.eps'.
-- -s:Indexed1:Indexed4:Indexed8: Try /SampleFormats in this order, and try
                 all others after these. Can be specified separately
                 (e.g `-s Indexed1 -s Indexed2:Indexed8')
-- -s:Indexed1:Indexed4:Indexed8:stop: Try only these /SampleFormats in
                 this order. Can be specified separately
                 (e.g `-s Indexed1:Indexed2 -s Indexed8:stop')
-- -s:Indexed1:Indexed4:Indexed8:stopq: Try only these /SampleFormats in
                 this order, be quiet (no warnings on failures). Can be
                 specified separately (e.g `-s Indexed1:Indexed2 -s Indexed8:stop')
-- -s:tr         equivalent to `-s Transparent:Opaque:Mask:Transparent2:Transparent4:Transparent8'
-- -l:...      : /LoadHints(...)
-- disabled: -a: /LoadHints(asis) extra /Compression/JAI; load JPEG files (and others as-is)

-- -1  -ps:1 PSL1:          : [tiff2ps] hint /FileFormat/PSL1 among /PSL*
-- -1c -ps:1c -ps:c PSLC:   : [pts] hint /FileFormat/PSLC among /PSL*
-- -2  -ps:2 PSL2: EPS2:    : [tiff2ps,imagemagick] default hint /FileFormat/PSL2 among /PSL*
-- -3  -ps:3 PSL3:          : [pts] hint /FileFormat/PSL3 among /PSL*
-- -pdf:b0 PDFB1.0:         : [pts] hint /FileFormat/PDFB1.0 among /PDF* (PDF 1.0 with inline image)
-- -pdf:b2 PDFB1.2:         : [pts] default hint /FileFormat/PDFB1.2 among /PDF* (PDF 1.2 with inline image; default because image processors usually keep inline images intact, so they wouldn't want to inefficiently recompress our image)
-- -pdf:0 PDF1.0:           : [pts] hint /FileFormat/PDF1.0 among /PDF* (PDF 1.0 with XObject image)
-- -pdf:2 PDF1.2:           : [pts] hint /FileFormat/PDF1.2 among /PDF* (PDF 1.2 with XObject image)
--  EPS: EPSF:              : [pts] hint /FileFormat/PSL2 or
                                         /FileFormat/PSL3 (for /Compression/ZIP)
--  PDF:                    : [pts] hint /FileFormat/PDFB1.0 or
                                         /FileFormat/PDFB1.2 (for /Compression/ZIP)
--  PS:                     :  [pts] hint /Scale/RotateOK /FileFormat/PSL2 or
                                          /FileFormat/PSL3 (for /Compression/ZIP)
--  PS2:                    : [imagemagick] hint /Scale/RotateOK
                                            /FileFormat/PSL2. Deprecated, please use PS:.

-- -e:0 -e:none -e:false    : /Scale/None
-- -e -e:1 -e:scale -e:true : /Scale/OK
-- -e:rot -e:rotate         : /Scale/RotateOK
-- -e:(false-bool)          : /Scale/None
-- -e:(true-bool)           : /Scale/OK

-- GIF: GIF89a: : [imagemagick,pts] /FileFormat/GIF89a
-- JPEG: JPG:   : [imagemagick,pts] /FileFormat/JPEG
-- TIFF: TIF:   : [imagemagick,pts] /FileFormat/TIFF
-- PNG:         : [imagemagick] /FileFormat/PNG
-- XPM:         : [imagemagick] /FileFormat/XPM
-- BMP:         : [imagemagick] /FileFormat/BMP
-- Empty:       : [pts] /FileFormat/Empty
-- Meta:        : [pts] /FileFormat/Meta
-- PIP:         : [pts] /FileFormat/PIP
-- PAM:         : [pts] /FileFormat/PAM
-- PNM:         : [imagemagick] /FileFormat/PNM (for use with transparency)
-- PBM:         : [imagemagick] /FileFormat/PNM /SampleFormat/Gray1
-- PGM:         : [imagemagick] /FileFormat/PNM /SampleFormat/Gray8
-- PPM:         : [imagemagick] /FileFormat/PNM /SampleFormat/Rgb8

-- -t:bin             : [pts] hint /TransferEncoding/Binary (default unless /PS*)
-- -t:hex             : [pts] hint /TransferEncoding/Hex (default for /PSL1 /PSLC)
-- -t:a85             : [pts] hint /TransferEncoding/A85 (default for /PSL2 /PSL3)
-- -t:ascii           : [pts] hint /TransferEncoding/ASCII
-- -t:lsb1 -f:lsb2msb : [pts,tiffcp] hint /TransferEncoding/LSBfirst
-- -t:msb1 -f:msb2lsb : [pts,tiffcp] hint /TransferEncoding/MSBfirst

-- -c:none                 : [pts,tiffcp] non-default hint /Compression/None
-- -c:zip:25:9             : [pts,tiffcp] ZIP, maximum effort, best predictor
-- -c:zip:(1..99):(-1..9)  : [pts] hint /Compression/ZIP /Predictor ... /Effort ...
-- -c:zip:(1..99)          : [pts] same as -c:zip(1..99):5
-- -c:zip                  : [pts,tiffcp] same as -c:zip:1:5
-- -c:lzw:25               : [pts] LZW, best predictor
-- -c:lzw:(1..99)          : [pts] hint /Compression/LZW /Predictor ...
-- -c:lzw                  : [pts,tiffcp] same as -c:lzw:1
-- -c:(rle|packbits)       : [pts,tiffcp] hint /Compression/RLE
-- -c:(rle|packbits):(0..) : [pts] hint /Compression/RLE /RecordSize ...
-- -c:fax                  : [pts] hint /Compression/Fax
-- -c:fax:(-1..)           : [pts] hint /Compression/Fax /K ...
-- -c:dct                  : [pts] hint /Compression/DCT /DCT<<>>
-- -c:dct:...              : [pts] hint /Compression/DCT /DCT<<...>>
-- -c:jpeg                 : [pts,tiffcp] hint /Compression/JAI, /Compression/IJG
-- -c:jpeg:(0..100)        : [pts] hint /Compression/JAI, /Compression/IJG /Quality ...
-- -c:ijgi                 : [pts,tiffcp] hint /Compression/IJG
-- -c:ijg:(0..100)         : [pts] hint /Compression/IJG /Quality ...
-- -c:g4                   : [pts] equivalent to -c:fax:-1
-- -c:g3 -c:g3:1d          : [pts] equivalent to -c:fax:0, -c:fax
-- -c:g3:2d                : [pts] equivalent to -c:fax:-2
-- -c:jai                  : [pts] hint /Compression/JAI

-- -m:dpi:(dimen)      : set /ImageDPI to `dimen'
-- -m:(dimen) \        : set all margins (/TopMargin,/BottomMargin, /LeftMargin, /RightMargin) to `dimen'
   -m:all:(dimen) \    :                  /LeftMargin, /RightMargin) to `dimen'
   -m:a:(dimen)        :
-- -m:horiz:(dimen) \  : set /LeftMargin and /RightMargin to `dimen'
   -m:h:(dimen) \      :
   -m:x:(dimen)        :
-- -m:vert:(dimen) \   : set /TopMargin and /BottomMargin to `dimen'
   -m:v:(dimen) \      :
   -m:y:(dimen)        :
-- -m:left:(dimen) \   : set /LeftMargin to `dimen'
   -m:l:(dimen)        :
-- -m:right:(dimen) \  : set /RightMargin to `dimen'
   -m:r:(dimen)        :
-- -m:top:(dimen) \    : set /TopMargin to `dimen'
   -m:t:(dimen) \      :
   -m:up:(dimen) \     :
   -m:u:(dimen)        :
-- -m:bottom:(dimen) \ : set /BottomMargin to `dimen'
    -m:b:(dimen) \     :
    -m:down:(dimen) \  :
    -m:d:(dimen)       :

-- --                  : if given as last arg, then   OutputFile:=InputFile
-- --                  : if given earlier than last arg, then    treat other args as filenames
-- -transparent:(rgb) Change the all pixels having the specified RGB color
   to transparent. Previously transparent pixels are not changed. See FAQ
   answer A44 for an exampe.

Default and fallback compression types for each file format:

-- PSL1 PSLC                  : /RLE
-- PSL2 PDFB1.0 PDF1.0        : /JAI /RLE
-- PSL3 PDFB1.2 PDF1.2        : /JAI /ZIP
-- GIF89a                     : /LZW
-- XPM PNM PAM PIP Empty Meta : )/None)
-- JPEG                       : /JAI /IJG
-- TIFF                       : /JAI /LZW? /RLE
-- PNG                        : /ZIP
-- BMP                        : /RLE

Overview of job mode
~~~~~~~~~~~~~~~~~~~~
In the ``job mode'' sam2p doesn't accept any command line options. It must be
controlled from the ``job'' files. In ''job mode'' sam2p expects a single command
line argument: the name of the Job file (file format described in section
{Jobs}). sam2p runs that single job, prints debug, info, notice, warning and
error messages (etc.), and creates a single output file: a PS or a PDF. For
multiple jobs and/or multiple output files, one has to run sam2p multiple
times.

The details about the output file format (including standards-compliance,
compression and transfer encoding) are specified in the Job file and other
files. Thus, in order to make use of the (basic and) advanced
features of sam2p in job mode, you have to:

1. Understand the basic concepts (i.e read through this manual, and have a
   look at the examples).
2. Prepare the input raster (bitmap) graphics file in one of the supported
   input formats (see section {Supported input formats}).
3. Decide the name of the output file.
4. Decide some or all details of the output format.
5. Create a Job file that describes those details.
6. Invoke the program `sam2p' with the name of the Job file as a single
   command-line argument (or `-' if the Job file is fed on STDIN).
7. Read warning and error messages (printed to STDOUT and STDERR), and retry
   if necessary.

Revision history, changes
~~~~~~~~~~~~~~~~~~~~~~~~~
See in the file debian/changelog.

Known bugs and issues
~~~~~~~~~~~~~~~~~~~~~
Please see pending bugs on https://github.com/pts/sam2p/issues .
Feel free to report any issue there if you encounter one! Your
bug reports and contributions are very welcome.

All of these old bugs had a follow-up elsewhere, or they don't need one:
https://code.google.com/archive/p/sam2p/issues .

If you are interested in fixed or closed bugs, please see them on
https://github.com/pts/sam2p/issues?q=is%3Aissue%20is%3Aclosed .

Requirements
~~~~~~~~~~~~
External software required for running sam2p:

-- operting system: any of:
   -- Linux
   -- Mac OS X
   -- Windows (any 32-bit Windows system released since 1995 will do;
      for older systems, install Wordpad to get MSVCRT.DLL)
   -- FreeBSD
   -- any UNIX system with a fairly standard BSD or POSIX C library (C++
      libraries are not required),
-- optionally: the libjpeg `cjpeg' utility for /Compression/IJG
-- optionally: the libjpeg `djpeg' utility for reading JPEG files
-- optionally: tif22pnm (uses libtiff) for reading TIFF files
-- optionally: png22pnm (uses libpng) for reading PNG files

Installation on Linux from package
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you use Debian, Ubuntu or some other .deb-based distribution on an i386
(x86) or amd64 (x86_64) system, download the latest .deb package from:

    https://github.com/pts/sam2p/releases

Install it like this:

    $ sudo dpkg -i sam2p_0.49.3-1_i386.deb

The executable in the .deb file doesn't have any library dependencies, it
works on any version of Debian and Ubuntu.

sam2p used to be included in Debian and Ubuntu for all architectures, but it
isn't anymore as of 2017-07-12 (it disappeared in 2016-01-22, see
https://tanguy.ortolo.eu/blog/article143/removing-sam2p-from-debian .)

If you need PNG input support, download the latest png22pnm.exe from:

    https://github.com/pts/tif22pnm/releases

Then put it to the same directory where sam2p.exe is.

If you need PNG input support, download the latest png22pnm.xstatic
executable from:

    https://github.com/pts/tif22pnm/releases

Then put it to your $PATH as tif22pnm, something like this:

    $ chmod 755 tif22pnm.xstatic
    $ sudo mv tif22pnm.xstatic /usr/local/bin/tif22pnm

Alternatively, tif22pnm may be available as a package on your Linux
distribution.

Using it on Linux without installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you use any Linux on an i386 (x86) or amd64 (x86_64) system, download the
latest sam2p.xstatic executable from:

    https://github.com/pts/sam2p/releases

Run it like this:

    $ mv sam2p.xstatic sam2p
    $ chmod 755 sam2p
    $ ./sam2p

The executable doesn't have any library dependencies, it works on any Linux
system.

If you need PNG input support, download the latest png22pnm.xstatic
executable from:

    https://github.com/pts/tif22pnm/releases

Then put it to your $PATH as tif22pnm, something like this:

    $ chmod 755 tif22pnm.xstatic
    $ sudo mv tif22pnm.xstatic /usr/local/bin/tif22pnm

Using it on FreeBSD without installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FreeBSD has a Linux subsystem, which is able to run sam2p. After activating
it, follow the instructions in the section {Using it on Linux without
installation}.

Using it on Windows without installation
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Download the latest sam2p.exe from:

    https://github.com/pts/sam2p/releases

Then copy sam2p.exe to the current directory, or to somewhere on your $PATH,
and run it as `sam2p' (without the quotes).

sam2p.exe has only standard Windows DLL dependencies, it works on any
Windows systems (i386 and amd64). If MSVCRT.DLL is missing, install Wordpad.

If you need PNG input support, download the latest png22pnm.exe from:

    https://github.com/pts/tif22pnm/releases

Then put it to the same directory where sam2p.exe is.

Compilation on UNIX
~~~~~~~~~~~~~~~~~~~
For Win32 compilation, see later.

Software required for UNIX compilation:

-- TL;DR You need these tools on the $PATH: sh perl g++ as ld
-- a UNIX system
-- sh: a Bourne-compatible shell (preferably GNU Bash >=2.0, but can be dash,
   ksh, zsh, busybox sh or others)
-- g++: a working, GNU-compatible C++ compiler (preferably GNU G++ >=2.91. Known
   working compilers: g++-2.91 g++-2.95 g++-3.0 g++-3.1 g++-3.2, g++-4.0,
   g++-4.4, g++-4.8, g++-6.3, g++-7.3)
-- perl: Perl >=5.004 (no external Perl modules are required)
-- (optional) make: GNU Make
-- (optional) autoconf: GNU autoconf >=2.53 (version number is important,
   see AC_C_CONST)
-- (not required): the following libraries are _not_ required: libjpeg,
   libtiff, libpng, libungif, PDFlib, zlib, libm

Compilation (it creates the executable file sam2p):

	sh compile.sh

If it doesn't work with your sh, you may want to try bash instead.

Alternative compilation if you don't want to link against libstdc++:

	sh compile_minigxx.sh

Alternative compilation for some targets, including cross-compilation: use
the ./compile_*.sh scripts.

If you want to use the ./configure script, run

	#sh configure --enable-gif --enable-lzw  # optional, make does it
	make
	# the stand-alone utility `./sam2p' is now built
	make install  # optional, may not work

If you have GNU Make as gmake on the $PATH, run this:

	sh configure MAKE=gmake --enable-gif --enable-lzw  # optional, gmake does it
	gmake
	# the stand-alone utility `./sam2p' is now built
	gmake install  # optional, may not work

If installation doesn't work, please copy the file `sam2p' to somewhere in
your $PATH, for example /usr/local/bin. Please also copy the README to a
directory like /usr/share/doc/sam2p. There is no man page -- the
documentation is the readme.

Testing:

	./sam2p
	./sam2p examples/ptsbanner_zip.job
	./sam2p examples/pts2.pbm try.eps
	gs test.ps
	# try other examples: examples/*.job

On Debian systems, you'll need GNU Make, Perl, GNU Bash and any of the
following packages for compilation:

	apt-get install libc6-dev gcc-2.95 g++-2.95
	apt-get install libc6-dev gcc-3.0 g++-3.0
	apt-get install libc6-dev gcc-3.1 g++-3.1
	apt-get install libc6-dev gcc-3.2 g++-3.2
	apt-get install libc6-dev gcc-3.3 g++-3.3
	apt-get install libc6-dev gcc-3.4 g++-3.4

Please also run any of the following before ./configure:

	export CC=gcc-2.95 CXX=g++-2.95
	export CC=gcc-3.0 CXX=g++-3.0 # or g++-3.1 etc.

Optionally, you may install any of

	apt-get install gccchecker
	apt-get install autoconf

sam2p has been tested with a wide variety of GNU C++ compilers, including
g++-2.91, g++-2.95, g++-3.0, g++-3.1, g++-3.2, i386-uclibc-g++-2.95,
checkerg++-2.95. The program must be compilable _without_ _warnings_ with
any of g++-2.91, g++-2.95, g++-3.0, g++-3.1, g++-3.2. If there is a
compilation error, send a brief e-mail to the author immediately!

Portability
~~~~~~~~~~~
sam2p is quite portable on UNIX systems. It runs on:

	Debian GNU/Linux Slink  2.2.13 glibc-2.0.7 (development platform)
	Debian GNU/Linux Potato 2.2.18 glibc-2.1.3
	Debian GNU/Linux Sid    2.4.17 glibc-2.2.5
	Digital OSF1 V4.0 1229 alpha
        Slackware 8.0/8.1       2.4.5  libc-2.2.3  gcc-2.95.3
	SunOS 5.7 Generic_106541-17 sun4u sparc SUNW,Ultra-2 gcc-2.95.2
	SunOS 5.8 Generic_108528-12 sun4u sparc gcc-3.0.4

Also it runs on Win32 in command line (sam2p.exe) and GUI mode (vcsam2p.exe).
Command line mode is stable and it is recommended on this platform.

It should work on any Linux or BSD system without modification. Porting to
other Unices should be quite easy. The author welcomes portability patches.

Porting to non-UNIX systems may be hard. Reasons:

-- Those systems might not have GNU Make, Perl or a Bourne-compatible shell
   installed. So the Makefile supplied won't work, and many man hours of extra
   work would be necessary.
-- sam2p uses the popen(3) library call to communicate with external
   processes. This call might not be available on non-UNIX systems.
-- sam2p expects that the $PATH contains the external binaries. Some systems
   tend to have empty or misconfigured $PATH. On some systems, `gs' is
   called `gswin32c.exe' etc.

sam2p 0.38 has been compiled and run successfully on:

-- Linux 2.2.8 Debian Slink, g++-2.91
-- Linux 2.4.18-ac3 Debian SID, g++-2.95, g++-3.0, g++-3.1, g++-3.2
   Executable size: 318kB.
-- Linux 2.4.2 Debian Potato, gcc version 2.95.2 20000220 (Debian GNU/Linux)
   No warnings.
   Compilation took 0:47, executable size: 330kB.
-- Linux 2.2.16-3 Red Hat Linux release 6.2 (Zoot), gcc version egcs-2.91.66 19990314/Linux (egcs-1.1.2 release)
   No warnings.
   Compilation took 0:44, executable size: 324kB.
-- OSF1 V4.0 564 alpha, gcc version 2.7.2.2
   (tons of: warning: cast discards `const' from pointer target type,
    tons of: warning: the meaning of `\x' varies with -traditional
    tons of: warning: cast increases required alignment of target type)
   Compilation took 5 minutes, executable size: 550kB.
-- SunOS 5.7 Generic_106541-19 sun4u sparc SUNW,Ultra-2, gcc version 3.1
   (some: warning: cast from `char*' to `int*' increases required alignment of target type)
   Compilation took 2:50, executable size: 437kB.
-- SunOS 5.8 Generic_108528-15 sun4u sparc, gcc version 3.1.1
   (some: warning: cast from `char*' to `int*' increases required alignment of target type)
   Compilation took 1:26, executable size: 437kB.
-- Slackware 8.0/8.1, kernel 2.4.5, libc.6.so (libc-2.2.3)  gcc-2.95.3

sam2p 0.42 has been compiled and run successfully on:

-- Windows 98, Visual C++ 6.0
-- Windows 98, MSYS, MingGW, G++ 3.2

Win32 compilation instructions for command-line mode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(These instructions are outdated.)

To compile sam2p.exe, the Win32 equivalent of the UNIX utility sam2p, you
have to install these build dependencies first:

-- MinGW and MSYS, available from http://www.mingw.org

-- Perl 5.004 or newer (only perl.exe and perl5*.dll are required), available
   from http://www.perl.com. Note that this will be a long download and a
   bloated install, but after that, just copy perl.exe and the single
   perl5*.dll to your C:\WINDOWS directory, and uninstall the rest.

To build sam2p:

1. Install all the build dependencies.

2. Open the MSYS terminal window from the start menu.

3. Run `explorer .' to figure out what is the current working directory.
   Let's call this directory the MSYS home.

4. Download the sam2p sources (.tar.gz) into the MSYS home from:

       https://github.com/pts/sam2p/releases

5. Unpack the sources. Run:

       tar xzvf sam2p-latest.tar.gz
       tar xvf sam2p-latest.tar.gz # if the previous one doesn't work

6. Run `cd sam2p-*.*' to enter the sam2p source directory. It should contain
   a newer version of this README and the file sam2p_main.cpp.

7. Run `perl -edie' to check whether Perl is correctly installed. It should
   print a line beginning with `Died '. If no such line appears (or you get
   a `command not found' error message), go and install Perl first. Run
   `echo $PATH' to find out where MSYS is searching for perl.exe. Copy
   perl.exe to one of those directories.

8. Run

	./configure --enable-gif --enable-lzw
	make

9. The file sam2p.exe is now created in the current directory. Use it. You
   may copy it to another directory right now:

	cp sam2p.exe 'C:\Program Files'

10. You should invoke sam2p.exe from the command line (COMMAND.COM or
    CMD.EXE) with the _appropriate_ arguments, described elsewhere in
    this document. Don't put it into the Start menu, it won't work.
    (a window will flash in and disappear, showing an error message that you
    haven't supplied the right arguments).

11. The file bts2.tth is also created. It is an important file, because it
    is required for the GUI compilation.

12. Don't forget to install tif22pnm.exe to load TIFF files, djpeg.exe to
    load JPEG files, cjpeg.exe to save JPEG files, and png22pnm.exe to load
    PNG files. The installation instructions for these programs are not
    given here.

Win32 compilation instructions for GUI mode
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
(These instructions are outdated.)

vcsam2p.exe is a preliminary, alpha-stage attempt to provide a Win32 GUI for
sam2p.exe. Currently it can load and display images, but not cannot save
them. vcsam2p.exe is not ready for production use.  Feel free to enhance the
code. Just remember to semd me copies.

You'll need Visual Studio 6.0 installed.

1. Download the sam2p sources (.tar.gz) from:

       https://github.com/pts/sam2p/releases

2. Download untarka.exe to be able to unpack the sources:

       http://.../untarka.exe

3. Unpack the sources. Run:

       untarka.exe sam2p-latest.tar.gz

   A directory sam2p-*.* will be created, containing a newer version of this
   README and the file config-vc6.h

4. You'll need bts2.tth. You can get an old, possibly outdated and buggy
   version directly:

	http://.../bts2.tth

   Or, you may compile sam2p under Linux (or Win32 command-line), and copy
   the generated bts2.tth from there.

   Copy bts2.tth to the same directory as config-vc6.h

5. Start the Visual C++ 6.0 environment.

6. File / Open Workspace / File type: Projects
                           Filename: vcsam2p.dsp
   Build / Set Active Configuration: vcsam2p - Win32 Release
   Build / Build vcsam2p.exe
   Build / Execute vcsam2p.exe

7. Don't forget to install tif22pnm.exe to load TIFF files, djpeg.exe to
   load JPEG files, cjpeg.exe to save JPEG files, and png22pnm.exe to load
   PNG files. The installation instructions for these programs are not
   given here.

Please report and fix bugs in vcsam2p.exe

Copyright
~~~~~~~~~
sam2p is written and owned by Szabó Péter <pts@fazekas.hu>. sam2p contains
code from various people.

sam2p may be used, modified and redistributed only under the terms of the
GNU General Public License, found in the file COPYING in the distribution,
or at

	http://www.fsf.org/licenses/gpl.html

Supported input formats
~~~~~~~~~~~~~~~~~~~~~~~
-- PNM, PBM, PGM, PPM (preferred formats for non-transparent images)
-- PNM+PGM, PNM+PBM. The input is a concatenation of a PNM and a P[GB]M
   file with the same dimensions. The second P[GB]M contains the alpha
   channel.
-- XPM (preferred formats for indexed images with transparency)
-- BMP
-- GIF, with transparency
-- LBM (IFF ILBM), with transparency
-- TGA (Targa)
-- baseline JPEG JFIF (limited by /Compression/JAI)
-- PCX
-- JPEG, is supported with libjpeg/djpeg
-- TIFF, is supported with the author's tif22pnm, with transparency; also
   works in a limited way with tifftopnm (Debian package libtiff-tools)
-- PNG, is supported with the author's png22pnm, with transparency
   (part of the tif22pnm sources); also works in a limited way with
    libpng/pngtopnm (Debian package graphics/pnmtopng); with transparency
-- PS, EPS, PDF: Ghostscript is needed (`gs' or `gswin32c.exe'), see also FAQ
   question Q39.

Note that only the major features of these file formats are supported. sam2p
is able to load most of these files, but not all of them.

Important, but unsupported input formats:

-- XBM
-- XWD
-- Utah RLE

Input image model
~~~~~~~~~~~~~~~~~
A (sampled, raster, bitmap) image is a rectangular array of pixels (dots)
plus some metadata. Each pixel is represented by an unsigned integer which
is BPC (BitsPerComponent) and CPP (ComponentsPerPixel) wide. The image
coordinate system (X,Y) is defined as: upper left corner is (0,0), upper
right corner is (Width-1,0), lower right corner is (Width-1,Height-1).
(Note that this is the natural, traditional top->down, left->right system,
and it is different from PostScript and PDF!).

Some pixels of the image may be without color: they're transparent. A
transparent pixel is not painted, so whatever was left under it on the
paper, remains visible. (On the other hand, a colored pixel overrides the
pixel below unconditionally. E.g a white pixel overrides a black pixel, a
half-gray pixel, and also another white pixel; but a transparent pixel
leaves the original one visible.). Notions referring to transparent pixels
are: transparency, opacity, transparent, opaque, alpha channel, matte
channel.

Images are read from image files on disk. The file format is autodetected
(see section {Supported input formats}), and it can also be specified in the
Job file (NOT implemented yet). Not all file formats are able to specify all
pixel data and metadata, so additional hints (such as the transparent color
or the name of the image author) can be specified in Job files.

Sample formats
~~~~~~~~~~~~~~
The image pixels could be packed to bytes according to several sample
formats. Each output file (both EPS and PDF) has its own SampleFormat
(notation: capitals).

A color is either transparent or it is an opaque RGB triplet (8*3 bits).

The number of colors is the number of colors actually _used_. So unused
palette entries, and e.g unused #555555 in gray-4 are not counted.

If PSLC is required, but the printer is only PSL1, then the color image will
be printed grayscale.

When _choosing_ the output format, sam2p doesn't degrade image quality. For
example, if an image has only two colors: #000001 and #ffffff, sam2p won't
allow the gray-1 sample format, but with #000000 and #ffffff, it will. The
user is expected to have an image editor in which she can adjust image
colors precisely (such as in the Dialogs/(Indexed palette) dialog of The
GIMP).

Supported Sample Formats:

Name:
	Fast compatibility
	Slow compatibility
	Criteria for the image
	-- Comment(...)

transparent: (specialisation of mask)
	all
	-
	the whole image is transparent
	-- implemented with empty image body
opaque: (specialisation of mask and indexed-1)
	all
	-
	the whole image contains the same, opaque color
	-- implemented with `setrgbcolor', `fill'
mask: (specialisation of transparent-2)
	all
	-
	a transparent and a non-transparent color (any may be missing)
	-- display a Warning if the whole image is transparent or opaque,
	   because transparent or opaque would be a better choice
	-- implemented with a single call to `imagemask'
indexed-1:
	all
	-
	exactly 2 non-transparent colors or 1 non-transparent color
	-- display a Warning if only 1 non-transparent color, because
	   opaque would be a better choice
	-- display a Notice if colors are in black (#000000) and white
	   (#ffffff), beacuse gray-1 would be a better choice
	-- implemented with a `setrgbcolor', `fill', and a single call to
	   `imagemask'
indexed-2:
	PSL2, PDF1.0??
	PSLC
	3 or 4 non-transparent colors or 1..2 non-transparent colors
	-- display a Warning if only 1..2 non-transparent colors, because
	   opaque or indexed-1 would be a better choice
	-- display a Notice if colors are in (#000000, #555555, #aaaaaa,
	   #ffffff), beacuse gray-2 would be a better choice
	-- implemented with the /Indexed color space or colorimage +
	   manual palette lookup
	-- users with a PSL1 printer without PSLC should use transparent-*
indexed-4:
	PSL2, PDF1.0??
	PSLC
	5..16 non-transparent colors or 1..4 non-transparent colors
	-- display a Warning if only 1..4 non-transparent colors, because
	   opaque, indexed-1 or indexed-2 would be a better choice
	-- display a Warning if all components are #00 or #ff,
	   because rgb-1 would be a better choice (3 bits over 4 bits)
	-- display a Notice if colors are in (#000000, #111111, ...,
	   #ffffff), beacuse gray-4 would be a better choice
	-- implemented with the /Indexed color space or colorimage +
	   manual palette lookup
	-- users with a PSL1 printer without PSLC should use transparent-*
indexed-8:
	PSL2, PDF1.0??
	PSLC
	17..256 non-transparent colors or 1..16 non-transparent colors
	-- display a Warning if only 1..16 non-transparent colors, because
	   opaque, indexed-1, indexed-2, indexed-4 would be a better
	   choice
	-- display a Warning if all components are #00, #55, #aa or #ff,
	   because rgb-2 would be a better choice (6 bits over 8 bits)
	-- display a Notice if all colors are gray, beacuse gray-8 would be
	   a better choice
	-- implemented with the /Indexed color space or colorimage +
	   manual palette lookup
	-- users with a PSL1 printer without PSLC should use transparent-*
transparent-2:
	all
	-
	0..1 transparent and 1..3 non-transparent colors
	-- display a Notice that color separation was done (which can
	   decrease speed and compression)
	-- display a Warning if no transparent color, because `indexed-2'
	   would be a better choice
	-- display a Warning if only 1 non-transparent color, because `mask'
	   would be a better choice
	-- implemented with multiple calls to `setrgbcolor', `imagemask'
transparent-4:
	all
	-
	a transparent and 1..15 non-transparent colors
	-- display a Notice that color separation was done (which can
	   seriously decrease speed and compression)
	-- display a Warning if only 1..3 non-transparent colors, because
	   `mask' or `transparent-2' would be a better choice
	-- implemented with multiple calls to `setrgbcolor', `imagemask'
transparent-8:
	all
	-
	a transparent and 1..255 non-transparent colors
	-- display a Warning that color separation was done (which can
	   seriously decrease speed and compression)
	-- display a Warning if only 1..15 non-transparent colors, because
	   `mask', `transparent-2' or `transparent-4' would be a better
	   choice
	-- implemented with multiple calls to `setrgbcolor', `imagemask'
gray-1:
	all
	-
	colors are in black (#000000) and white (#ffffff)
	-- display a Warning if only 1 color, because opaque would be a
	   better choice
	-- implemented with the multiple-argument `image'
gray-2:
	all
	-
	colors are in (#000000, #555555, #aaaaaa, #ffffff)
	-- display a Warning if only 1..2 colors, because opaque,
	   indexed-1, or gray-1 would be a better choice
	-- implemented with the multiple-argument `image'
gray-4:
	all
	-
	colors are in (#000000, #111111, ..., #ffffff)
	-- display a Warning if only 1..4 colors, because opaque,
	   indexed-1, gray-1, indexed-2 or gray-2 would be a better choice
	-- implemented with the multiple-argument `image'
gray-8:
	all
	-
	colors must be gray
	-- display a Warning if only 1..16 colors, because opaque,
	   indexed-1, gray-1, indexed-2, gray-2, indexed-4 or gray-4
	   would be a better choice
	-- implemented with the multiple-argument `image'
rgb-1:
	PSLC, PDF1.0
	-
	color components must be #00 or #ff (8 colors max)
	-- display a Warning if all colors are gray
	-- display a Warning if only 1..4 colors, because opaque,
	   indexed-1, indexed-2 (or gray-*) would be a better choice
	-- implemented with `colorimage'
rgb-2:
	PSLC, PDF1.0
	-
	color components must be #00, #55, #aa or #ff (64 colors max)
	-- display a Warning if all colors are gray
	-- display a Warning if only 1..16 colors, because opaque,
	   indexed-1, indexed-2 or indexed-4 (or gray-*) would be a better choice
	   choice (this includes the case when color components are in
	   #00, #ff)
	-- implemented with `colorimage'
rgb-4:
	PSLC, PDF1.0
	-
	color components must be #00, #11, ... #ff (4096 colors max)
	-- display a Warning if all colors are gray
	-- display a Warning if only 1..256 colors, because opaque,
	   indexed-1, indexed-2, indexed-4 or indexed-8 (or gray-*) would be a better
	   choice (this includes the case when color components are in
	   #00, #55, #aa, #ff)
	-- implemented with `colorimage'
rgb-8:
	PSLC, PDF1.0
	-
	no transparency
	-- display a Warning if all colors are gray
	-- display a Warning if only 1..256 colors, because opaque,
	   indexed-1, indexed-2, indexed-4 or indexed-8 (or gray-*) would be a better
	   choice
	-- display a Warning if all color components are in
	   #00, #11, ... #ff, because rgb-4 would be a better choice
	-- implemented with `colorimage'

The following directed (acyclic) graph represents that some formats should
be tried earlier than others to avoid most Warning and Notice messages. The
graph was created according to the descriptions above.

	EarlierFormat LaterFormat

	transparent mask
	opaque mask
	opaque indexed-1
	indexed-1 indexed-2
	indexed-2 indexed-4
	indexed-4 indexed-8
	gray-1 gray-2
	gray-2 gray-4
	gray-4 gray-8
	rgb-1 rgb-2
	rgb-2 rgb-4
	rgb-4 rgb-8
	gray-1 indexed-1
	gray-2 indexed-2
	gray-4 indexed-4
	gray-8 indexed-8
	rgb-1 indexed-4
	rgb-2 indexed-8
	mask transparent-2
	transparent-2 transparent-4
	transparent-4 transparent-8
	opaque gray-1
	indexed-1 gray-2
	indexed-2 gray-4
	indexed-4 gray-8
	opaque rgb-1
	gray-1 rgb-1
	gray-2 rgb-2
	gray-4 rgb-4
	gray-8 rgb-8
	indexed-2 rgb-1
	indexed-4 rgb-2
	indexed-8 rgb-4
	indexed-8 rgb-8

Every directed acyclic graph (DAG) has a topological ordering on its nodes.
Such an ordering can be computed by the UNIX (Version 7 AT&T UNIX) utility
tsort(1). Its output on the author's machine:

	opaque
	transparent
	gray-1
	indexed-1
	mask
	transparent-2
	gray-2
	indexed-2
	transparent-4
	rgb-1
	gray-4
	indexed-4
	transparent-8
	rgb-2
	gray-8
	indexed-8
	rgb-4
	rgb-8

This ordering should be taken into account when someone develops her
Rule Profile. Rules having SampleFormats listed earlier should be earlier in
the Rule Profile to avoid Warning and Notice messages.

The availability (and also Warnings and Notices) of a Sample Format for a
particular image can be easily decided after answering the following
characteristic questions:

-- Is transparency _used_?
-- How many _used_ non-transparent colors are there? (257 if >=257)
-- Is there a non-gray color?
-- How many bits are required (maximum) for each component?

Output rules
~~~~~~~~~~~~
Every detail of the output file format is precisely determined by the Output
Rule. The Output Rule may be specified in the Job file, or is
automatically chosen from several pre-defined output rules in the Output
Profile (see section {Output profiles} elsewhere in this document).

Output rule entries:

-- FileFormat: enum (see section {Standards} for detailed information), no
   default
   /PSL1      -- PostScript Level1
   /PSLC      -- PostScript Level1 with the CMYK and `colorimage' extension
   /PSL2      -- PostScript Level2 (default)
   /PSL3      -- PostScript Level3
   /PDFB1.0   -- PDF version 1.0, BI inline image, see 4.8.6 in PDFRef.pdf
   /PDFB1.2   -- PDF version 1.2, BI inline image, see 4.8.6 in PDFRef.pdf
   /PDF1.0    -- PDF version 1.0, XObject image, see 4.8.4 in PDFRef.pdf
   /PDF1.2    -- PDF version 1.2, XObject image, see 4.8.4 in PDFRef.pdf
   /GIF89a
   /Empty
   /Meta
   /PNM
   /PAM
   /PIP
   /TIFF
   /JPEG
   /PNG
   /XPM

-- SampleFormat: enum, no default, see section {Sample formats}
   /Opaque
   /Transparent
   /Gray1
   /Indexed1
   /Mask
   /Transparent2
   /Gray2
   /Indexed2
   /Transparent4
   /Rgb1
   /Gray4
   /Indexed4
   /Transparent8
   /Rgb2
   /Gray8
   /Indexed8
   /Rgb4
   /Rgb8
   /Asis       -- accept contents of the JAI file
   /Bbox       -- no image, only bounding box information
-- WarningOK: boolean; this Output Rule is enabled iff WarningOK is true or
   SampleFormat causes no warnings, default: true
-- TransferEncoding: enum, no default
   /Binary -- Binary (RawBits, see pbm(5), pgm(5), ppm(5)) (Binary integers
   are stored in any byte order allowed by /FileFormat)
   /ASCII -- ASCII (text, chars: 9,10,13,32..126), used with transparent and opaque
   /Hex /AHx -- Hex ((PSL1), PDF1.0, PSL2 ASCIIHexEncode filter)
   /A85 -- A85 (PSL2 PDF1.0, ASCII85Encode filter)
   /MSBfirst -- Binary data with integers stored in MSB first byte order.
     If 0x41424344 is represented as "ABCD", the byte order is called: big
     endian, MSB, MSB first (preferred), most significant byte first, most
     significant bit first, MSB-to-LSB, network byte order, m68k byte order.
     QuarkXPress 3 can read only TIFF files with MSB-to-LSB byte order.
   /LSBfirst -- Binary data with integers stored in LSB first byte order.
     If 0x41424344 is represented as "DCBA", the byte order is called:
     little endian, LSB, LSB first (preferred), least significant byte
     first, least significant bit first, LSB-to-MSB, VAX byte order, PC
     (i386) byte order.
-- Compression: enum
   /None -- None (default)
   /LZW -- LZW (PSL2 PDF1.0 LZWEncode filter EarlyChange=true, UnitLength=8
     LowBitFirst=false)
   /ZIP /Flate /Fl -- ZIP (PSL3 PDF1.2 FlateEncode filter without options)
   /RLE /RunLength /RunLengthEncoded /RL /PackBits -- RLE (PSL2 PDF1.0
     RunLengthEncode filter, similar to TIFF PackBits)
   /Fax /CCITTFax /CCF -- Fax (PSL2 PDF1.0 CCITTFaxEncode filter,
     Uncompressed=true!, K=-1,0,1, EndOfLine=false, EncodedByteAlign=false,
     Columns=..., Rows=0, EndOfBlock=true, BlackIs1=false,
     DamagedRowsBeforeError=0)
   /DCT -- DCT (PSL2 PDF1.0 DCTEncode, options in JPEG
     stream)
   /IJG /JPEG /JPG /JFIF -- IJG (PSL2 PDF1.0 DCTEncode, options in JPEG
     stream; the IJG libjpeg library is used for compression, respecting the
     quality value 0..100). This requires /SampleFormat/Rgb8 or
     /SampleFormat/Gray8. This doesn't work with /SampleFormat/Asis.
   /JAI -- JAI (PSL2 PDF1.0 DCTEncode, options in JPEG stream; JPEG-as-is: the
     input file must be a JPEG file -- its contents are transferred
     unmodified into the /DCTDecode JPEG stream). This requires
     /SampleFormat/Asis, and doesn't work with any other /SampleFormats
-- Predictor: enum (see below), default is 25 (except if -c:zip or -c:lzw is
   specified without more parameters, because then 1 is used), numbering is
   same as PSL1 filter.
   Affects PNG output, PS output (with -c:zip:... and -c:lzw:...), PDF
   output (with -c:zip:... and -c:lzw:...), TIFF output (with -c:zip:... and
   -c:lzw:...).
   1 -- (default if -c:zip or -c:lzw is specified without more parameters)
        No predictor. If FileFormat is PNG, then 10 is used instead.
   2 -- TIFF predictor 2 (horizontal differencing)
   10 -- PNG predictor, None function
   11 -- PNG predictor, Sub function
   12 -- PNG predictor, Up function
   13 -- PNG predictor, Average function
   14 -- PNG predictor, Paeth function
   15 -- PNG predictor, individually chosen for each line (absolute minimum)
   25 -- (default if -c:zip and -c:lzw are notespecified)
         Use 15 if FileFormat supports 15 (PS, PDF or PNG),
         Compression supports predictors (ZIP or LZW) and SampleFormat
         is Gray8 or Rgb8; use 10 if FileFormat is PNG; otherwise use 1.
         and use 1 (no predictor) for everything else. This is the default.
         For PNG output, this is the same as what libpng uses by default.
   45 -- PNG predictor, individually chosen for each line (unsigned minimum)
         Don't use this, it generates a large output file.
   55 -- PNG predictor, individually chosen for each line (signed minimum)
         Don't use this, it generates a large output file.
-- Transparent: color. Default: null. Specify a color forced to be
   transparent. Old transparency, if exists, is blacked!
-- Hints: dict
   see below

The Hints member of the Output Rule contains a dict with the following
elements:

-- TopMargin           : dimen; desired vertical gap between the top line of the page
                           and the top line of the raster. Default: 0. Ignored unless for PS
                           and PDF output. See docs about `dimen' elsewhere in this document.
-- BottomMargin        : dimen; desired vertical gap between the bottom line of the
                           raster and the bottom line of the page. Default: 0. Ignored unless
                           for PS and PDF output. See docs about `dimen' elsewhere in this document.
-- LeftMargin          : dimen; desired horizontal gap between the left line of the page and
                           the left line of the raster. Default: 0. Ignored unless for PS and PDF
                           output. See docs about `dimen' elsewhere in this document.
-- RightMargin         : dimen; desired horizontal gap between the right line of the raster and
                           the right line of the page. Default: 0. Ignored unless for PS and PDF
                           output. See docs about `dimen' elsewhere in this document.
-- ImageDPI            : positive number; resolution of bitmap image in dots per inch.
                           Default: 72, which means no scaling.
-- Scale               : enum /None -- don't scale (zoom, magnify) the image (default)
                              /OK -- scale PS image to fit page (x factor == y factor)
                              /RotateOK -- scale and/or rotate PS image to fit page (x factor == y factor)
-- EncoderBPL          : int >=1 (bits per scanline, <= rlen)
-- EncoderCoumns       : int >=1 (pixels per scanline)
-- EncoderRows         : int >=1
-- EncoderColors       : int >=1
-- PredictorColumns    : uint; also used if compression is /Fax (reasonable default)
-- PredictorColors     : 1..3; number of color _components_ (reasonable default)
-- PredictorBPC        : 1, 2, 4, 8 (reasonable default), /BitsPerComponent entry in PS and PDF
-- Effort              : -1..9, must be -1 unless Compression is /ZIP (-1 means 5, default)
-- RecordSize          : uint, default: 0. Compression must be /RLE
-- K                   : int, default:  0 (-2..infty). Compression must be /Fax.
                                       -1 means G4 1d encoding,
                                        0 meangs G3 1D encoding,
                                       -2 means G3 2D encoding with  arbitrary height, positive value
                                       means G3 2D encoding with that height.
-- Quality             : 0..100, used by IJG libjpeg when compression is /IJG. default: 75
-- ColorTransform      : 0..2. For IJG, this _must_ be 0 for Gray and 1 for RGB, so its value
                           is ignored. For DCT, its value is respected: use 0 or 1 only.  See DCTEncode
                           in subsubsection 3.13.3 in PLRM.pdf, and for a better documentation: see the
                           sources and docs of libjpeg.
-- TransferCPL         : number of data characters per line. Must be positive when TransferEncoding is
                           /Hex or /A85, and must be zero otherwise.  Default: 78
-- DCT                 : dict, default: <<>>. Additional parameters for the /DCTEncode filter
-- Comment             : string, default: empty
-- Title               : string, default: empty
-- Subject             : string, default: empty
-- Author              : string, default: empty
-- Creator             : string, default: empty
-- Producer            : string, default: empty
-- Created             : string, default: now
-- Produced            : string: default: now

Metric units
""""""""""""
Certain parameters have type `dimen'. This is a metric dimension, measured
in any of the following real-word distance metric units:

--  1 bp = 1 bp (big point)
--  1 in = 72 bp (inch)
--  1 pt = 72/72.27 bp (point)
--  1 pc = 12*72/72.27 bp (pica)
--  1 dd = 1238/1157*72/72.27 bp (didot point) [about 1.06601110141206 bp]
--  1 cc = 12*1238/1157*72/72.27 bp (cicero)
--  1 sp = 72/72.27/65536 bp (scaled point)
--  1 cm = 72/2.54 bp (centimeter)
--  1 mm = 7.2/2.54 bp (millimeter)

Note: If it helps: American typesetters use 72 points per US inch,
thus  10 pt text will yield 72 chars per normal line of US Letter
      (like an IBM Selectric)
      12 pt text will yield 65 chars per normal line of US Letter
     (US normal typewritter).

Each image pixel is assumed to be 1 bp wide and 1 bp tall. A dimen is an
integer or real number, followed by optional whitespace and an optional unit
(any of `bp', `in', `pt', `pc', `dd', `cc', `sp', `cm', `mm'). The default
unit is `bp', i.e a bare number is a dimen measured in `bp'. The following
dimens are all one inch long: `72', `72bp', `72 bp', `1in', `1 in',
`2.54cm', `25.4mm', `72.27pt', `6pc', `4736286.72sp'.

Note: MiniPS and TeX use the same units.

OutputRule combinations
~~~~~~~~~~~~~~~~~~~~~~~
In the final version of sam2p, the following combinations will be supported:

LZW >=2 Binary|Hex|A85 >=PSL2|>=PDF1.0 Mask|Gray*|RGB*|Indexed*
LZW >=2 Binary|Hex|A85 >=PSL2|>=PDF1.0 Transparent+
ZIP >=2 Binary|Hex|A85 >=PSL3|>=PDF1.2 Mask|Gray*|RGB*|Indexed*
ZIP >=2 Binary|Hex|A85 >=PSL3|>=PDF1.2 Transparent+
None|ZIP|LZW|RLE|Fax|DCT|IJG 1 Binary|Hex|A85 >=PSL2|>=PDF1.0 Mask|Gray*|RGB*|Indexed*
None|ZIP|LZW|RLE|Fax|DCT|IJG 1 Binary|Hex|A85 >=PSL2|>=PDF1.0 Transparent+
None 1 ASCII >=PSL1|>=PDF1.0 Opaque
None 1 ASCII >=PSL1|>=PDF1.0 Transparent
ZIP  1 Binary|Hex|A85 >=PSL1 Gray*|RGB*|Indexed*
ZIP  1 Binary|Hex|A85 >=PSL1 Mask|Gray1|Indexed1
ZIP  1 Binary|Hex|A85 >=PSL1 Transparent+
None 1 Binary|Hex|A85 >=PSL1 Gray*|RGB*|Indexed*
None 1 Binary|Hex|A85 >=PSL1 Mask|Gray1|Indexed1
None 1 Binary|Hex|A85 >=PSL1 Transparent+
RLE  1 Binary|Hex|A85 >=PSL1 Gray*|RGB*|Indexed*
RLE  1 Binary|Hex|A85 >=PSL1 Mask|Gray1|Indexed1
RLE  1 Binary|Hex|A85 >=PSL1 Transparent+
JAI  1 Binary|Hex|A85 >=PSL2|>=PDF1.0 Asis

TTM files
~~~~~~~~~
TTM stands for Template Toy Macro.

A TTM file is a dirty hack for generating templates with auto-calculated
lengths and offsets. Currently they are used for generating PDF output files
(/FileFormat/PDFB10 etc.). The syntax
of a TTM file is MiniPS (i.e a minimalistic PostScript, similar to .job
files). The TTM file must contain a single MiniPS array.

The elements of the array are called chunks. Each chunk causes some bytes
to be appended to the output file. Data is appended in the order the
chunks are listed in the TTM file, but the data calculation order may be
different. This way it is possible to write (calc) the length of a chunk
not written (filled in) yet. The very first chunk has number zero.
different. This way it is possible to write the length of a chunk not
written yet. The very first chunk has number zero.

The chunk types:

-- string: backtick-sequences will be substituted (e.g ``w' to the width of
   the image, in pixels) by writeTemplate(). The result is appended to the
   output file.
-- positive integer: The offset (zero-based byte-position of the very first
   character of chunk 0) of the specified chunk will be appended to
   the output file. Only chunks already appearead may be specified this
   way. If the specified chunk is an array, then printf("%10u") will be
   called to print the number (this is useful for making PDF xref tables),
   otherwise printf("%u") will be called.
-- negative integer: The length (measured in bytes, after substitutions)
   of the specified chunk will be appended to the output file, using
   printf("%u"). Only chunks already calculated may be specified this way.
-- zero: error
-- array: the array is interpreted as a standalone TTM subfile, and the rules
   are applied recursively. This subfile contains sub-chunks, and the
   subchunks may be arrays themselves.
-- other MiniPS types: error

The chunks are calculated in the following order: first the array chunks are
calculated (recursively) in order of appearance, followed by the non-array
chunks in order of appearance.

A TTM file can have up to 64 top-level chunks.

Example:

	[ 1              %0
	  [ (pts) ]      %1.0
	  -1             %2
	]

The output file will be: `3pts0000000001' since chunk 1 has length 3 and
offset 1.

Example job file
~~~~~~~~~~~~~~~~
	<<%sam2p job
	% This is file (named test0.job).
	/InputFile  (test0.pbm)
	/OutputFile (test0.pdf)
	/Profile [
	  % This in-line profile is preferred over the defaults
	  << /FileFormat/PDF10 /SampleFormat/Gray1 /TransferEncoding/Binary
	     /Compression/Fax /Hints<</K 99>> >>
	  (pdf10.jib) run  % elements found in external file
	]
	>>

See the directory examples/*.job in the sam2p sources.

sam2p vs convert in 2017
~~~~~~~~~~~~~~~~~~~~~~~~
Several test runs were done on 2017-07-12 with the latest sam2p and the
convert tool in ImageMagick 6.7.7-10 to compare the performance of both
output file size and processing speed.

Conclusions:

-- Don't use convert for EPS output, because with `eps3:' it produces
   an output file with non-ASCII characters, which is incompatible with many
   systems, and with `eps:' it produces huge output files. Use e.g. sam2p
   instead.
-- For PDF output and JPEG or PNG input, the latest version of both convert
   and sam2p are fast enough and produce an output of reasonable size.
-- For PDF output and some PNG input (especially if the image has at most
   16 colors), sam2p can be faster and produce much smaller output than
   convert. (This was not compared here.)

Raw performance data:

-- A run on a 4048x3036 landscape photo JPEG, file size 3009251 bytes:

   $ time jpegtran -optimize -copy none <beach.jpg >beach.opt.jpg
   0.14s user 0.02s system 99% cpu 0.170 total
   output file size: 2955545 bytes
   (jpegtran removes some unnecessary markes from the JPEG)

   $ time sam2p beach.jpg beach.jpg.sam2p.pdf
   0.00s user 0.01s system 90% cpu 0.011 total
   output file size: 3009793 bytes
   $ time convert beach.jpg beach.jpg.convert.pdf
   0.39s user 0.07s system 138% cpu 0.333 total
   output file size: 2983807 bytes
   (convert is a bit smarter removing unnecessary markers from the JPEG)
   $ time convert beach.opt.jpg beach.opt.jpg.convert.pdf
   0.41s user 0.17s system 136% cpu 0.419 total
   output file size: 2965683 bytes
   $ time sam2p beach.opt.jpg beach.opt.jpg.sam2p.pdf
   0.00s user 0.01s system 90% cpu 0.014 total
   output file size: 2956087 bytes
   (now, without the unnecessary markers, the output of sam2p is smaller)

   $ time sam2p beach.jpg beach.jpg.sam2p.eps
   0.02s user 0.01s system 96% cpu 0.035 total
   output file size: 3809826 bytes
   $ time convert beach.jpg eps3:beach.jpg.convert.eps
   0.27s user 0.04s system 86% cpu 0.359 total
   output file size: 2979366 bytes
   (the file is small, because convert doesn't apply /ASCII85Decode,
    thus breaks the embedding of the EPS on some systems)
   $ time sam2p -t:bin beach.opt.jpg beach.opt.jpg.sam2p_n.eps
   0.00s user 0.00s system 84% cpu 0.006 total
   output file size: 2955974 bytes
   (that's very close to the input JPEG file size, better than convert)

-- A run on a 4048x3036 landscape photo PNG, file size 11508728 bytes:

   $ time sam2p beach.png beach.png.sam2p.pdf
   4.07s user 0.15s system 99% cpu 4.223 total
   output file size: 12471057 bytes
   $ time convert beach.png beach.png.convert.pdf
   2.01s user 0.13s system 106% cpu 2.015 total
   output file size: 18095807 bytes
   (convert is faster, but its output PDF is much larger)

   $ time sam2p beach.png beach.png.sam2p.eps
   2.63s user 0.18s system 99% cpu 2.812 total
   output file size: 15734187 bytes
   $ time convert beach.png eps3:beach.png.convert.eps
   1.87s user 0.06s system 99% cpu 1.933 total
   output file size: 18079080 bytes
   (the file is larger, but it's still not fair to compere,
    because convert doesn't apply /ASCII85Decode,
    thus breaks the embedding of the EPS on some systems)
   (convert is faster because sam2p is slow to read PNG files)
   $ time sam2p -t:bin beach.png beach.png.sam2p_n.eps
   2.52s user 0.24s system 99% cpu 2.761 total
   output file size: 12428098 bytes
   (that's the fair comparison of sizes)

Some comments:

-- Converting JPEG to PDF or EPS is fast for both sam2p and convert, because
   JPEG decoding and encoding is not done. sam2p is even faster, because
   it doesn't do lossless optimizations.
-- When converting JPEG, convert removes some JPEG markers and does some
   lossless optimizations (similar but less
   than what `jpegtran -optimize -copy none' removes), thus the output of
   convert is smaller than sam2p. However, if we run the jpegtran command
   first, then the output of sam2p becomes smaller.
-- When creating EPS files with convert, `eps3:' should be specified as
   the output format, because `eps:' would create much larger files, mostly
   because of worse compression algorithms and hex-encoding.
-- Older versions of convert created much larger EPS files, mostly because
   they included an uncompressed image preview.
-- With the `eps3:' output format of convert, the EPS file will contain
   non-ASCII characters, which is incompatible with some systems, and
   it cannot be fixed with a command-line flag. sam2p applies /ASCII85Decode
   (-t:a85) by default, producing an ASCII output file. Thus convert doesn't
   have a good option: with `eps:' output files are huge; with `eps3:'
   output files are incompatible with some systems.
-- convert is generally slower than sam2p, except when reading PNG files
   (for which sam2p is about 1.5 times slower). convert used to be much
   slowen that it is now.
-- sam2p has fewer dependencies and the total binary size is smaller than of
   convert. This can make startup time faster, and it can make it easy to
   install to systems without sam2p packaged.
-- sam2p is smart and fast, and it produces small output with images with a
   few colors only (2..16). (It doesn't matter if these colors are encoded
   as a palette or RGB.) There were no such images in this test run.
-- sam2p gives control to the user to fine-tune compression and other
   settings for EPS and PDF, and convert doesn't. The defaults of sam2p are
   tuned for the general use case though.

FAQ
~~~
Q1. Should I care about /LoadHints (,asis,) when loading JPEG files?

A1. No, sam2p guesses it by magic (in both job mode and one-liner mode).
    However, you may want to set it manually in job mode:

	/LoadHints () % use djpeg
	/LoadHints (,asis,) % don't use djpeg
	% nothing: automatic guess, based on /Compression/JAI

Q2. How do I convert a JPEG file to PostScript Level2 EPS?

A2. In one-liner mode, just run:

	./sam2p <INPUT.jpg> <OUTPUT.eps>
	Example: ./sam2p try.jpg try.eps

    In one-liner mode, if you have both the djpeg and cjpeg utilities
    (budled with libjpeg from IJG (Independent JPEG Group)), _and_ you want
    to adjust quality vs size of the output, just run:

	./sam2p -c:jpeg:<QUALITY> <INPUT.jpg> <OUTPUT.eps>
	Example: ./sam2p -c:jpeg:60 try.jpg try.eps

    In job mode, just run sam2p with the following .job file:

	<<%sam2p-job;
	% conversion is possible without external utilities cjpeg and djpeg
	% No quality loss, just verbatim adata copying.
	/InputFile  (INPUT.jpg)
	/OutputFile (OUTPUT.eps)
	/Profile [
	  << /FileFormat/PSL2 /SampleFormat/Asis /TransferEncoding/A85
	     /Compression/JAI >>
	] >>

    Alternatively, to adjust quality vs size, use the following .job file:

	<<%sam2p-job;
	% external utilities cjpeg and djpeg are required
	% This uses a JPEG decompression (djpeg), plus lossy JPEG compression
	% (cjpeg), so there might be quality loss!
	/InputFile  (INPUT.jpg)
	/OutputFile (OUTPUT.eps)
	/Profile [
	  << /FileFormat/PSL2 /SampleFormat/Rgb8 /TransferEncoding/A85
	     /Compression/IJG /Hints <<
	       /Quality 40 % 0..100 (should be at least around 30)
	  >> >>
	] >>

Q3. How do I convert a GIF file to PostScript Level2 EPS?

A3. Check that sam2p has been compiled with GIF support: run sam2p, and
    examine its console output. It should contain a line:

	Available Loaders: ... GIF ...

    If GIF doesn't appear in the line, please recompile sam2p with:

	make clean
	./configure --enable-gif --enable-lzw
	make
	cp sam2p /usr/local/bin

    After that, run sam2p again, and check for the line above again.

    In one-liner mode, just run:

	./sam2p <INPUT.gif> <OUTPUT.eps>
	Example: ./sam2p try.gif try.eps

    In job mode, if the GIF file doesn't have transparent pixels, run sam2p
    with the following .job file:

	<<%sam2p-job;
	/InputFile  (INPUT.gif)
	/OutputFile (OUTPUT.eps)
	/Profile [
	  << /FileFormat/PSL2 /SampleFormat/Indexed8 /TransferEncoding/A85
	     /Compression/None >>
	] >>

    If the GIF file has transparent pixels, run sam2p with the following .job
    file:

	<<%sam2p-job;
	/InputFile  (INPUT.gif)
	/OutputFile (OUTPUT.eps)
	/Profile [
	  << /FileFormat/PSL2 /SampleFormat/Transparent8 /TransferEncoding/A85
	     /Compression/None >>
	] >>

Q4. How do I covert a JPEG file to a TIFF/JPEG output file?

A4. A TIFF/JPEG file is a TIFF file (_not_ a JPEG file!), in which the image
    data is compressed with JPEG (DCTEncode compression). The Compression
    TIFF tag value is 7. (There is also Compression==6, which corresponds to
    the old, obsolete JPEG format defined in the old TIFF6.0 spec.)

    In one-liner mode, autodetection is magical. Just run:

	./sam2p <INPUT.jpg> <OUTPUT.tiff>
	Example: ./sam2p try.jpg try.tiff

    In job mode, run sam2p with the following .job file:

	<<%sam2p-job;
	/InputFile  (INPUT.jpg)
	/OutputFile (OUTPUT.tiff)
	%/LoadHints (asis) % default for /Compression/JAI
	/Profile [
	  << /FileFormat/TIFF /SampleFormat/Asis /TransferEncoding/Binary
	     /Compression/JAI >>
	] >>

    See also {FAQ question Q5} for compatibility notes.

Q5. The TIFF/JPEG file generated by sam2p is invalid! I cannot read it with
    any programs.

A5. No, it isn't invalid, but most of the programs (including those found in
    libtiff) cannot deal with TIFF files with JPEG compression.

    Compatibility notes:

    -- tif22pnm 0.03 (from the author of sam2p) can read TIFF/JPEG files
       perfectly. That's because it calls the TIFFRGBAImageGet() function
       of libtiff, which works.

    -- sam2p 0.37 can read TIFF/JPEG files, beacuse it calls tif22pnm to do
       the job. Sam2p can write TIFF/JPEG files as well.

    -- GIMP 1.0.2: error message: `Unknown photometric number 6'. GIMP TIFF
       import filter cannot deal with the YCbCr color space (which is the
       most common and de facto standard color space in non-grayscale JPEG
       files). It works, however, with grayscale JPEGs.

    -- tifftopnm from libtiff-tools 3.4beta037-5.1: `unknown photometric:
       6'. Ditto. (Unfortunately tifftopnm doesn't call TIFFRGBAImageGet(),
       it just tries to re-implement an obsolete version of the function.)

    -- `tiffcp -c jpeg' from libtiff-tools 3.4beta037-5.1 creates a
       perfectly legal TIFF/JPEG file.

    -- tiffcp from libtiff-tools 3.4beta037-5.1 cannot load a file created
       by itself (`tiffcp -c jpeg')! There is no problem with grayscale
       images, but color images have one component removed.

    -- xv 3.10a: Ditto.

    -- display from ImageMagick 4.04: strange error message about libraries:
       `JPEGLib: Wrong JPEG library version: library is 61, caller expects 62.'

    Simple conclusion:

    -- Use sam2p or `tiffcp -c jpeg' to create a TIFF/JPEG. (Be aware that
       `tiffcp -c jpeg' cannot read a TIFF/JPEG: it can only create one.)
    -- Use tif22pnm to load or decode a TIFF/JPEG.
    -- In your own C programs, call the TIFFRGBAImageGet() function to read
       TIFF image data.
    -- Don't use anything else if you want to avoid compatibility problems.

Q6. Does sam2p support transparency and alpha channels?

A6. sam2p supports only bilevel transparency (i.e a pixel is either fully
    opaque or fully transparent), and only with indexed images. Transparency
    is supported when loading indexed PNG, TIFF, PNM, GIF, LBM and XPM files.
    A PNM file with transparency is a regular PBM/PGM/PPM file with a
    PBM image appended to it as the alpha channel (black pixel is
    transparent).

    For transparent output, the user has to specify /Transparent, /Mask,
    /Transparent2, /Transparent4 or /Transparent8 as /SampleFormat. This
    works with:

    -- /FileFormat/PSL1+    /SampleFormat/Transparent
    -- /FileFormat/PDF1.0+  /SampleFormat/Transparent
    -- /FileFormat/PDFB1.0+ /SampleFormat/Transparent
    -- /FileFormat/PSL1+    /SampleFormat/Mask
    -- /FileFormat/PDF1.0+  /SampleFormat/Mask
    -- /FileFormat/PDFB1.0+ /SampleFormat/Mask
    -- /FileFormat/GIF89a   /SampleFormat/Mask
    -- /FileFormat/PNM      /SampleFormat/Mask
    -- /FileFormat/TIFF     /SampleFormat/Mask
    -- /FileFormat/PNG      /SampleFormat/Mask
    -- /FileFormat/XPM      /SampleFormat/Mask
    -- /FileFormat/PSL1+    /SampleFromat/Transparent+
    -- /FileFormat/GIF89a   /SampleFormat/Transparent+
    -- /FileFormat/PNM      /SampleFormat/Transparent+
    -- /FileFormat/TIFF     /SampleFormat/Transparent+
    -- /FileFormat/PNG      /SampleFormat/Transparent+
    -- /FileFormat/XPM      /SampleFormat/Transparent+

Q7. How large is a pixel of PostScript and PDF files generated by sam2p in
    real-world metric units (inches or centimeters)?

A7. 72 big points == 1 inch == 2.54 centimeters

    1 pixel == 1 big point

Q8. I have an image with transparent pixels. What happens if I convert it to
    /Rgb* or /Gray*?

A8. Either of the following will happen:

    -- You get an error message, sam2p refuses to ignore transparency.
       Please use /SampleFormat/Transparent+, or call an image manipulation
       program to remove transparency from the image before feeding it to
       sam2p.
    -- Transparency information will be lost, and the color of formerly
       transparent pixels will be undefined. This would be a bug in sam2p,
       you should report it.

    However, if you loaded a GIF file, and
    transformed it to /Gray8 or /Rgb8, the original palette entry (RGB
    triplet) is faithfully preserved.

Q9. How do I generate a PostScript page ready for immediate printing with
    margins and the image properly scaled to fit the page?
    How do I create a PostScript file that will automatically scale the
    image to the maximum when printed?


A9. To print an image as a full PostScript page, call:

	./sam2p [MARGIN-SPECS] <INPUT.IMG> ps: - | lpr
	Example: ./sam2p -m:1cm examples/pts2.pbm ps: - | lpr

    To create a PostScript file for printing, call:

	./sam2p [MARGIN-SPECS] <INPUT.IMG> [ps:] <OUTPUT.ps>
	Example: ./sam2p -m:1cm examples/pts2.pbm try.ps

    The `-m' option above is sets all four margins to `1 cm'. You can
    set the margins individually:

	Example: ./sam2p -m:left:7mm -m:right:1cm -m:top:0.5in \
          -m:bottom:18bp examples/pts2.pbm try.ps

    As you can see in this example, you may specify dimensions in various
    metric units, see subsection {Metric units}.

    You are strongly encouraged to print raster images with sam2p. Be aware
    that The GIMP 1.2 printing plugin has several weird contrast setting
    problems (even for /Gray1 images); white pixels will be gray etc. Other
    utilities may add unnecessary text banners or scale the image
    inappropriately.

    In one-liner mode, sam2p guesses from the file extension and the selector
    (`ps:') whether the desired output file format is PostScript (fit single
    page) or Encapsulated PostScript (leave size as-is, suitable for
    inclusion into TeX documents).

    In job mode, without /Scale/OK and /Scale/RotateOK in /Hints,
    sam2p outputs EPS (Encapsulated PostScript) with /FileFormat/PSL*. EPS
    files should be included as figures into other documents (such as TeX
    and InDesign), not printed alone. If you just want to print a sampled
    image alone, please use your favourite graphics manipulation program
    instead of sam2p.

    In job mode, create a .job file for the EPS file, and add /Hints. For
    example:

     <<%sam2p-job;
     /InputFile  (test.in)
     /OutputFile (test.ps)
     /Profile [
       << /FileFormat/PSL2 /SampleFormat/Rgb8 /TransferEncoding/A85
          /Compression/None /Predictor 1
          /Hints << /Scale/OK % or /Scale/RotateOK
                    /LeftMargin 12 % measured as number/72 inches
                    /Rightargin 12 % measured as number/72 inches
                    /TopMargin 12 % measured as number/72 inches
                    /BottomMargin 12 % measured as number/72 inches
                 >>
       >>
      ]
     >>

Q10. Do the EPS files created by sam2p conform to some specifications?

     The EPS output of sam2p conforms to the following Adobe specifications:

	5001.DSC_Spec.pdf
	5002.EPSF_Spec.pdf

     DSC and ADSC are: Adobe Document Structuring Conventions. They are
     comments with lines beginning with `%!' and `%%' in PS and EPS files.

     An excerpt:

	The following example illustrates the proper use of DSC comments in a
	typical page description that an application might produce when including an
	EPS file. For an EPS file that is represented as

	%!PS-Adobe-3.0 EPSF-3.0
	%%BoundingBox: 4 4 608 407
	%%Title: (ARTWORK.EPS)
	%%CreationDate: (10/17/89) (5:04 PM)
	%%EndComments
	...PostScript code for illustration..
	showpage
	%%EOF

     DSC comments discussion:

	%!PS-Adobe-3.0 EPSF-3.0 (mandatory)
	%%BoundingBox: ... ... ... ... (mandatory)

  	%%Extensions: CMYK (optional, for /PSLC)
	%%LanguageLevel: 2 (optional, for /PSL2)
	%%LanguageLevel: 3 (optional, for /PSL3)
	%%Creation (strongly recommended)
	%%Title (strongly recommended)
	%%CreationDate (strongly recommended)
	%%Trailer (optional)
	%%EOF (optional)
	%%DocumentData: Clean7Bit (optional)
	%%DocumentData: Binary (optional)

Q11. I get the error message `sam2p: Error: applyProfile: invalid
     combination, no applicable OutputRule'. Help!

A11. This error message means you have requested an invalid combination of
     FileFormat, SampleFormat, Compression etc. parameters. If you use
     one-liner mode, and you're sure that you've specified your will
     correctly in the command line, please report this error message as a
     sam2p bug (also specify -j in the command line). If you use job mode,
     please read on.

     Example 1:
       /Compression/Fax is not allowed in /PSL1.

     Solution 1:
       specify /FileFormat/PSL2 /Compression/Fax.

     Example 2:
       /Compression/IJG requires /SampleFormat/Gray8 or /SampleFormat/Rgb8.
       Please have a look at the messages `sam2p: Warning: check_rule: ...'
       to get more specific information. After that, correct your request.

     Solution 2:
       specify /Compression/IJG /SampleFormat/Rgb8.

     Another cause for this message is that your request cannot be applied
     to the image you've specified. In this case, there is no relevant
     `sam2p: Warning: check_rule: ...' message.

     Example 1:
       you've requested /SampleFormat/Indexed4,
       but the input image has more than 16 colors.

     Solution 1:
       specify /SampleFormat/Rgb8.

     Example 2:
       you've requested /SampleFormat/Indexed4,
       but the input image has transparency.

     Solution 2:
       specify /SampleFormat/Transparent8.

     It is possible, but very unlikely that this error message is caused by
     a bug in sam2p.

Q12. Can I use /Compression/Fax when bits-per-pixel > 1 ?

A12. With /FileFormat/PS* and /FileFormat/PDF*, you can (but you shouldn't,
     because of the possibly poor compression ratio). With /FileFormat/TIFF,
     you're not allowed to, because the TIFF specification forbids it.
     Example one-liners:

	sam2p -s:Indexed8 -c:fax test.gif test.pdf   # OK
	sam2p -s:Indexed8 -c:fax test.gif test.eps   # OK
	sam2p -s:Indexed8 -c:fax test.gif test.tiff  # forbidden

Q13. Bad luck?

A13. Not for me.

Q14. Can I use negative margins (i.e /TopMargin -20) to crop the output
     image?

A14. No. Margins are ignored by sam2p unless /FileFormat is /PSL* or /PDF*.
     Even with these formats, the image is only moved, not cropped. Please
     use an image manipulation program (e.g The GIMP) to crop your images
     before feeding them to sam2p.

Q15. When I try to print the PostScript output of sam2p, the edge of the
     image is missing (white).

A15. Many printers cannot print to the edge of the paper (so that region is
     left white). Please increase the margins to a safe value, for example:

	./sam2p -m:7mm test.ppm test.ps
	lpr test.ps

     See also {FAQ question Q9} for more information about margins.

Q16. How do I report a bug in sam2p?

A16. Please send an e-mail to the author (pts@fazekas.hu, see more in
     section {Copyright}) describing the problem. Don't forget to:

     -- download the latest version of sam2p, and try it with the same image
     -- describe what sam2p does (incorrectly)
     -- describe what sam2p should do if there was no bug
     -- run sam2p without arguments, and attach its output (STDOUT) to the
        bug report
     -- attach the exact command line with which you call sam2p to the bug
        report
     -- if you spot the bug in one-liner mode, specify the `-j' option in
        the command line, and attach the messages printed by sam2p (both
        STDOUT and STDERR) to the bug report
     -- if you spot the bug in job mode, attach the .job file you are using
        to the bug report
     -- attach the input image file to the bug report. Try to attach a file
        as small as possible.
     -- if sam2p runs successfully (i.e it prints `Success.'), and it
        creates an output image, but you think that the output image is
        incorrect, attach the output image to your bug report
     -- if you have a similar input image, for which sam2p works fine,
        attach it to the bug report

Q17. How long does the LZW patent held by Unisys last?

A17. mcb@cloanto.com (author of http://lzw.info) wrote:

     Thank you for your interest and mail. I must stress that the "exact"
     answers you may be looking for may come only from lawyers and courts,
     and I am none of these. If you consider the IBM, the BT and Unisys US
     patents, then the last of the three would be the Unisys one, expiring,
     as the article I think mentions, on June 19, 2003, 24:00. There cannot
     be other (new) patents on LZW, as far as I know. Please let me know if
     you find different information.

Q18. I want to create an RGB PostScript image, but sam2p creates a Gray one,
     or it gives me an error message.
     For example: `./sam2p -1 -s:rgb1 examples/ptsbanner.gif test.eps'.

A18. /PSL1 doesn't support RGB images. There are two solutions:

     -- Use /PSLC or /PSL2 or /PSL3 instead or drop the '-1'
        alltogether. Examples:

	./sam2p -1c -s:rgb1 examples/ptsbanner.gif test.eps  # /PSLC
	./sam2p -2  -s:rgb1 examples/ptsbanner.gif test.eps  # /PSL2
	./sam2p     -s:rgb1 examples/ptsbanner.gif test.eps  # /PSL2 or /PSL3

     -- Use /Mask or /Transparent+. Note that you'll very probably get poor
        compression ratio.

	./sam2p -1 -s:tr:stop examples/ptsbanner.gif test.eps  # /PSL1

     You can get more (and more useful) error messages from sam2p if you
     specify the `-j:warn' option. You may also try specifying
     `-s:rgb1:stop' instead of `-s:rgb1' to force sam2p try /SampleFormat/Rgb1
     only.

Q19. sam2p doesn't allow me to use /Compression /Fax. For example:
     `./sam2p -c fax examples/ptsbanner.gif test.eps'. The same command
     works fine without `-c fax'.

A19. /Compression/Fax is intended to be used with images with 1 bit per
     pixel. However, in PostScript and PDF, you can use it for any image
     data, but compression ratio will be very poor for other than /Gray1,
     /Indexed1 or /Mask, of course. You can force sam2p to use /Fax by
     specifying the desired SampleFormat in option `-s'. Examples:

	sam2p -s:Indexed8 -c:fax test.gif test.pdf   # OK
	sam2p -s:Indexed8 -c:fax test.gif test.eps   # OK
	sam2p -s:Indexed8 -c:fax test.gif test.tiff  # forbidden by TIFF std

     See {FAQ question Q12} for more information.

Q20. Can sam2p convert images with transparency to PDF?

A20. Only if the image has at most 1 non-transprent color
     (/SampleFormat/Mask). See {FAQ question Q6} for details.

     Although PDF-1.3 supports transparency masks for arbitrary PDF images,
     sam2p 0.39 doesn't. That's because the author of sam2p hasn't
     implemented it yet.

Q21. I get the error message `sam2p: Warning: buildProfile: ignoring, no
     handlers for OutputRule'. Help!

A21. This means that sam2p doesn't know how to do the conversion you've
     requested (and it even doesn't know whether the request is erroneous or
     not). This might be because your request is bad (it is impossible to
     be fulfilled), or your request is good, but sam2p doesn't know how to
     deal with it. If you think that the latter is the case, please report
     this message as a bug.

     See {FAQ question Q11} for more information.

Q22. How do I compile with G++ 3.2?

A22. See the answer in section {Compilation and installation}. Don't forget

	export CC=gcc-3.2 CXX=g++-3.2

Q23. How do I do a `make dist' without running configure again?

A23. Just issue

	make MAKE_DIST=1 dist

Q24. I cannot open a JPEG file in the Win32 version.

A24. Make sure you have djpeg.exe on your PATH. Simply copy it to your
     C:\WINDOWS directory.

Q25. I cannot open a TIFF file in the Win32 version.

A25. Make sure you have tif22pnm.exe on your PATH. Simply copy it to your
     C:\WINDOWS directory.

Q26. I cannot open a PNG file in the Win32 version.

A26. Make sure you have png22pnm.exe on your PATH. Simply copy it to your
     C:\WINDOWS directory.

Q27. What is tif22pnm?

A27. tif22pnm is a TIFF -> PNM converter written by the author of sam2p. It
     can load more TIFF files correctly than tifftopnm, ImageMagick convert,
     xv and The GIMP. The TIFF loader code is based on GIMP 1.3, but has
     many bugfixes and improvements. sam2p uses tif22pnm to load TIFF files.
     You can download tif22pnm from

        https://github.com/pts/tif22pnm

Q28. What is png22pnm?

A28. png22pnm is a PNG -> PNM converter compiled by the author of sam2p. It
     is based on the excellent pngtopnm utility, but doesn't depend on the
     NetPBM library (only libpng). sam2p uses png22pnm (or, as a fallback:
     pngtopm) to load PNG files. png22pnm is part of the tif22pnm package,
     so you can download it from

         https://github.com/pts/tif22pnm

Q29. Can sam2p convert a transparent GIF to PDF?

A29. The PDF-1.3 file format supports transparent images, but sam2p doesn't.
     However, if the image contains at most two colors (including the
     transparent pixel), sam2p can create a working PDF-1.2 file; use
     Ghostscript to view it, because Acrobat Reader 5.0 is buggy. However,
     sam2p supports generating transparent EPS, GIF, PNG, PNM, XPM and TIFF
     files up to 256 colors.

Q30. How do I build my own sam2p debian package?

A30. Please download the newest sources (.tar.gz) from

	https://github.com/pts/sam2p

     As root, run

	apt-get update
	apt-get install debmake fakeroot dpkg
	apt-get install make g++ gcc perl sed

     As normal user, run (in the directory containing sam2p_main.cpp):

	debian/rules clean
	rm -f build*
	debian/rules build
	fakeroot debian/rules binary
	ls -l ../sam2p_*.deb

     As root, substitute X and Y, and run:

	dpkg -i sam2p_X_Y.deb

     Please also install the tif22pnm and png22pnm packages from the author
     of sam2p (and the Debian standard libjpeg-progs package), available as
     Debian source from:

	https://github.com/pts/tif22pnm

Q31. Why not use libjpeg/libtiff/libpng/zlib or any other library with
     sam2p?

A31. -- library and .h incompatibilities (the binary would be less portable
        across Linux systems)
     -- to avoid forced dependencies
     -- checkergcc wouldn't work

Q32. How do I specify the page size when printing a .ps file (-m and -e
     command line options)?

A32. You cannot. (Use -m to specify the margins.) The page size is
     autodetected by your printer when the page is
     printed. So you can print the same .ps file on different printers, and the
     margins will be all right on all of them.

     If you really have to specify the page size, edit the .ps file and
     insert the `a4 ' or `letter ' command after the last line of the
     first block of lines starting with %%. You may also use something like
     `1 dict dup /PageSize [ 595 842 ] put setpagedevice ' to exactly specify
     the page width and height in 1/72 inches.

     For example, change the PostScript file

       %!PS-Adobe-3.0
       %%Pages: 1
       %%DocumentData: Clean7Bit
       %%LanguageLevel: 1
       %%EndComments
       %%Page: 1 1
       save
       ... % many lines omitted
       %%Trailer
       %%EOF

     to

       %!PS-Adobe-3.0
       %%Pages: 1
       %%DocumentData: Clean7Bit
       %%LanguageLevel: 1
       %%EndComments
       %%Page: 1 1
       1 dict dup /PageSize [ 595 842 ] put setpagedevice
       save
       ... % many lines omitted
       %%Trailer
       %%EOF

     Please note that PostScript is a programming language, so your changes
     might be undone by instructions later in the file. You might find the
     a2ping.pl utility (written by the author of sam2p) useful:

       a2ping.pl -v --papersize=a4 in.ps out.ps

Q33. How do I control ZIP compression ratio?

A33. Use

	sam2p -c:zip:1:0 in.img out.png  # uncompressed ZIP carrier
	sam2p -c:zip:1:1 in.img out.png  # little compression
	sam2p -c:zip     in.img out.png  # default normal compression
	sam2p -c:zip:1:5 in.img out.png  # default normal compression
	sam2p -c:zip:1:9 in.img out.png  # maximum compression

Q34. ImageMagick convert creates smaller PNGs. Why?

A34. I don't know the real reason.  Probably because ImageMagick uses libpng,
     which is smarter than sam2p.

     You are probably trying to convert a JPEG or other true color photo to
     PNG. Try one of the following compression options:

	sam2p -c:zip:12:7   # 464727 bytes
	sam2p -c:zip:12:8   # 454271 bytes
	sam2p -c:zip:12:9   # 447525 bytes
	sam2p -c:zip:13:9   # 488748 bytes
	sam2p -c:zip:14:9   # 454182 bytes
	sam2p -c:zip:15:9   # 453080 bytes
	convert -quality ?  # 454438 bytes

Q35. Can sam2p convert large JPEGs to smaller ones (with loss of
     quality and resolution)?

A35. sam2p cannot resize or scale images. So the pixel width and height of
     the input and output image cannot be changed. If you need that (for
     example you want to create thumbnails), use the famous convert(1)
     utility of ImageMagick. For example:

	convert -scale 444   -quality 50 in.jpg out.jpg  # specify out width
	convert -scale x444  -quality 50 in.jpg out.jpg  # specify out height
	convert -scale "10%" -quality 50 in.jpg out.jpg  # specify scale ratio

     However, it is possible to specify the quality of the JPEG output of
     sam2p. The quality of 0 means ugly output with small file size, and the
     quality of 100 means nice output with big file sizes. You can specify
     intermediate integer quality values (50 and 75 are recommended). Be
     prepared that qualties above 30 (or so) may not work on all JPEG viewers.
     For example:

	 sam2p -c ijg:10 large_input.jpg small_output.jpg

     sam2p uses the cjpeg(1) and djpeg(1) utilities from libjpeg to write
     and read JPEG files, respectively. If you need more control over your
     JPEG output, then forget sam2p, and please consult the documentation of
     those utilities.

Q36. Can sam2p convert JPEG to GIF?

A36. Yes, it can, but usually not directly. GIF allows a maximum of 256
     different
     colors in an image. A typical RGB JPEG image contains many more colors,
     so it has to be quantized down to 256 colors first. For example, if the
     console output of ``sam2p in.jpg out.gif'' contains ``applyProfile:
     invalid combination, no applicable OutputRule'', then in.jpg must be
     quantized first:

	convert in.jpg out1.gif  # does the quantization automatically
	sam2p out1.gif out2.gif  # compresses the output image further

     From out1.gif and out2.gif keep the one with the smaller file size. It
     is common that convert(1) creates huge GIF files because LZW compression
     is disabled inside it. sam2p should be compiled with LZW compression
     and GIF input/output enabled. To check this, run sam2p, and
     examine its console output. It should contain a line:

	Available Appliers: ... GIF89a+LZW ...

     If GIF89a+LZW doesn't appear in the line, please recompile sam2p with:

	make clean
	./configure --enable-gif --enable-lzw
	make
	cp sam2p /usr/local/bin

     , and try again.

Q37. I need to transform GIF images of 15 colors to BMPs of 256 colors not
     compressed. sam2p converts it to BMP 16 colors...

A37. Use

	sam2p -c none -s rgb8 in.gif out.bmp

     If you get an error message `Error: applyProfile: invalid combination,
     no applicable OutputRule', it very probably means that your GIF is
     transparent. Remove the transparent color within an image editor first.

Q38. Can sam2p _load_ PDF or EPS files?

A38. Yes, if you have Ghostscript installed, and your input EPS file is not
     too exotic. This has been tested on Linux only. If you experience
     problems loading EPS files, but no problems loading PDF files, please
     run a2ping.pl written by the author of sam2p to make your EPS file more
     compatible.

Q39. Can sam2p load an EPS or PDF file with an arbitrary resoultion?

A39. Yes. For example use one of

	sam2p -l:gs=-r216 in.eps out.png
	sam2p -l:gs=-r216 in.pdf out.png

     to have resoultion 216 DPI (image scaled 3 times to both directions).
     Without scaling, 72 DPI is the default.

Q40. Can sam2p emit a multi-page PDF or a multi-page PS?

A40. No, it can't. Emitting a multi-page document would need a fundamental
     change of the sam2p architecture. (Should the 2nd page be compressed with
     a different method? What if the 2nd contains too many colors? Should we
     keep all previous pages in memory?)

     I think another program should be written that is able to concatenate
     EPS/PS or PDF files. I've already written a PDF-merger called pdfconcat,
     available from https://raw.githubusercontent.com/pts/pdfconcat/master/pdfconcat.c
     . An EPS-merger would be even easier. But I don't have time to
     implement these features directly into sam2p soon.

Q41. Can sam2p read a multi-page TIFF?

A41. sam2p reads only the first page.

     The auxilary utility tif22pnm could be patched so it extracts other
     pages, and a new command line option can be added to sam2p that passes
     the required page number to tif22pnm. But I don't have time to
     implement these features soon.

     By the way, multi-page TIFFs can be created with the following command:

	tiffcp -c g4 d1.tiff d2.tiff d3.tiff output.tiff

Q42. Can sam2p convert a multi-page TIFF to a multi-page PDF?

A42. No. There are two main problems: See also Q40 and Q41.

Q43. How do I convert a TIFF image to a 1-bit black-and-white PDF? Should I
     use `sam2p -c:fax test.tif test.pdf'?

A43. The above will ensure that fax compression is used. What you need for
     ensuring that the output is 1-bit black-and-white is:

        sam2p -s:gray1:stop test.tif test.pdf

     You can also specify a compression algorithm (I recommend -c:zip):

        sam2p -c:fax -s:gray1:stop test.tif test.pdf
        sam2p -c:lzw -s:gray1:stop test.tif test.pdf
        sam2p -c:zip -s:gray1:stop test.tif test.pdf

     If you get the error message

        sam2p: Error: applyProfile: invalid combination, no applicable OutputRule

     then your input test.tif is not really black-and-white. Open it in an
     image editing program and ensure that the colors are #000000 and
     #ffffff only.

     > The tiff is black and white, bilevel - I just want to avoid the
     > test.pdf from using 8bpp by default (like it does in imagemagick)

     The default for sam2p is not 8bpp. To see what the default is, run sam2p
     with the `-j' option and check `OutputRule #1' on the console output.
     What you are interested in is the /SampleFormat field.

Q43. Acrobat Reader (5.0 and 6.0) cannot read the PDFs converted from a JPEG
     with sam2p. I get the message: `There was an error processing a page.
     Expected `EI' while parsing an image.'.
     (The same problem happens with Ghostscript 6.50 with a different error
     message. xpdf-1.0 reports: bad DCT trailer.)

A43. Very probably the JPEG stream of your original input image file is
     rejected by the PDF viewers. (In fact, Ghostscript 7.x doesn't
     complain.) sam2p doesn't do strict JPEG validation when converting JPEG
     to PDF -- it just blindly assumes that the JPEG file is correct. To
     ensure this, you have to re-encode the JPEG.

     Instead of this:

       sam2p bad.jpeg bad.pdf

     do this:

       sam2p -c ijg:50 bad.jpeg good.pdf  # much slower!

     or this:

       <bad.jpeg djpeg | cjpeg -quality 50 | sam2p - good.pdf

     or this:

	djpeg <bad.jpeg >temp.pnm
	cjpeg -quality 50 <temp.pnm >temp.jpeg
	sam2p temp.jpeg good.pdf

     The real reason why Acrobat Reader rejects the JPEG is unknown to me.
     I also don't know of any baseline JPEG compliance testing software.
     (But if you re-encode with djpeg and cjpeg, it becomes compliant.)

     (thanks to Thomas Kraemer for reporting the problem)

Q44. How do I create an 1x1 transparent GIF and PNG?

A44. Do

	echo "P1 1 1 0" >one.pbm
	sam2p -transparent:ffffff one.pbm one.gif
	sam2p -transparent:ffffff one.pbm one.png

Q45. Is it possible to specify a resolution other than 72 DPI, so that the
     dimensions of the resulting PDF are accurate for print-resolution images?

A45. Yes, it is. Use `-m:dpi:144' to have the output EPS or PDF scaled to
     double size, or use `-m:dpi:<real>' to have it scaled by a factor of
     <real>/72, or 72/-<real>, if <real> is negative.

     If you know that your input image resolution is <res> DPI, and you want
     to sam2p to create an EPS or PDF keeping the image resolution, you
     should use `-m:dpi:-<res>'.

     Note that this works only for EPS and PDF output. For all other
     FileFormat{}s, `-m:dpi:' is ignored. The `-m:dpi:' option doesn't scale
     the values specified for the other `-m:...' options.

     Some image file formats such as PNG an JPEG can contain resolution
     information. sam2p ignores this and assumes that the input image
     resolution is 72 DPI). It would be possible to improve sam2p to use
     this information, but it would be too much work.

     To proper way of scaling an image, however, is
     using your DTP or word processor program to resize it properly. For
     example, after running `sam2p foo.png foo.pdf', in LaTeX, use

        % \usepackage{graphicx}
        \includegraphics[height=10cm]{foo}

Q46. Is it legal to use LZW compression?

A46. I think so. Also look at Q17.

Q47. Help! I cannot compile it on SunOS/Solaris. I get

     /usr/include/sys/wait.h:90: type specifier omitted for parameter
     /usr/include/sys/wait.h:90: parse error before `*'

A47. Until someone adds a test to ./configure, try adding the line

       #define siginfo_t void

     to the end of config2.h, just before running `make'.

Q48. Should I run sam2p over all my EPS (or PDF) files, to see if they
     would become smaller?

A48. No! This is a bad idea in general, because you lose information, since
     the EPS output of sam2p is always rasterized, so it is not scalable
     anymore.

     But you may run sam2p over all those EPS files which contain raster
     graphics. But please be aware that sam2p re-renders everything at 72
     DPI (can be overridden by `-l:gs=-r<DPI>', and the gs rendering
     sometimes adjusts RGB color values slightly (+-2 on in the 0..255
     domain), so there might be quality loss during the _reading_ of the
     original EPS. There is absolutely no quality loss when sam2p _writes_
     the EPS.

Q49. Should I run sam2p over all my GIF, TIFF and XPM files, to see if they
     would become smaller?

A49. Yes, run `sam2p <filename> --' if you have a backup copy of the
     original. Otherwise, choose a different filename for output.

Q50. Should I run sam2p over all my PNG files, to see if they
     would become smaller?

A50. You might try it, there will be no quality loss, but the general
     experience of the author is that the tools using libpng (e.g. pnmtopng)
     produce slightly smaller PNG than sam2p. If you are an image
     compression specialist, please help the author to find the reason of
     this, and enhance sam2p.

Q51. Should I run sam2p over all my JPEG files, to see if they
     would become smaller?

A51. sam2p doesn't change the file by default. Use the `-c:ijg' option
     (possibly with a JPEG quality parameter, e.g. `-c:ijg:50') to make
     sam2p re-encode the JPEG. This is a lossy operation, and the size of
     the output file depends on quality parameter specified, so it might
     actually become larger than the original. Please also note that JPEG
     meta-information (such as EXIF tags inserted by digital cameras) gets
     completely lost with `-c:ijg'.

Q52. How do I use ZIP (Deflate) compression in LanguageLevel 2?

A52. Run this:

	sam2p -c:zip PSL2: in.image out.eps

     This will make sam2p emit the image decoding procedure so the image
     will be viewable (veeeery slowly) on LanguageLevel 2 devices, too. It
     doesn't affect the rendering speed on LanguageLevel 3 devices.

Q53. How do I create a GIF from an image with more than 256 colors?

A53. You need the pnmquant utility too from NetPbm. Run this:

       sam2p in.image PPM:- | pnmquant 256 | sam2p - out.gif

     Or, if you have the convert utility from ImageMagick, run:

       sam2p in.image PPM:- | convert - out.gif

Q54. What is the maximum image size sam2p supports?

A54. As of version 0.45, the following limits apply for input images:

     -- Input image height times image width must be <= 2000000000 pixels.
        Individual dimensions can be as high as necessary.
     -- Input image memory must be <= 1000000000 bytes (1 GiB). The memory is
        computed by multiplying image width, image height and BPC. BPC is
        number of bytes per pixels. It is 3 for RGB images, 1 for grayscale
        and indexed (256-color palette) images. For some temporary
        calculations BPC might go up to 3 even if it is smaller than 3 in
        the input image, so to be safe, always assume that BPC is 3 in image
        memory calculations.
     -- For JPEG input or ouput, image width and height must be <= 65535
        pixels.
        This is an inherent limitation in the JPEG file format.

     In earlier versions (0.44 or below) the following additional limits
     applied:

     -- Image width must be <= 65535 pixels.
     -- Image height must be <= 65535 pixels.

     sam2p is a fast image conversion tool: it isn't unnecessarily slow on
     large images. Its speed is predictable for uncompressed images: it
     slows down proportionally to the input image memory (see the
     calculation below).

Q55. How do I get the smallest PNG output?

A55. If your input image is truecolor, please consider a lossy compression
     file format (such as JPEG), because the ZIP compression used in PNG is
     not particularly well-suited for truecolor images.

     If your input image has only a few colors, specify `-c zip:25:9', which
     forces the ZIP compression whith a high effort (9) and predictor
     autodetection (25). This is considerably slower than not specifying any
     `-c' flag at all, and getting `-c zip:25', because the high effort (9)
     is slower than the default effort. Please note that `-c zip:25:9'
     disables the predictor unless the SampleFormat is Rgb8 or Gray8. (This
     is the same what libpng-1.2.15 does by default.) For large images (of
     Rgb{1,2,4,8} or Gray{1,2,4,8}), you may want to specify `-c zip:15:9'
     to forcibly enable the predictor, being autodetected for each image
     row.

     Please also note that the free software ``optipng'' and the free-to-use
     closed-source software PNGOUT (for Win32, Linux and Mac OS X) can
     produce PNGs about 10% smaller than what sam2p produces -- but they are
     a 100 times (or even more) slower than sam2p. The tool ``pnmtopng''
     (tested with one linked to libpng 1.2.20) does not produce smaller PNGs
     than sam2p >= 0.46. For older versionf of sam2p, the output of
     ``pnmtopng'' was about 5--10% smaller.

     Please also note that the the PNG output of Ghostscript -sDEVICE=pngmono
     etc. is not optimal. Convert it with sam2p or the tools mentioned above
     to reduce the file size.

Q56. How do I get the smallest PDF output?

A56. If your input image is truecolor, specify `-c jpeg', possibly tuning it
     with a low quality parameter e.g. `-c jpeg:30'.

     If your input image has only a few colors, specify `-c zip:25:9' or
     `-c zip:15:9', see also Q55.

     Please also have a look at Q55. Unfortunately, sam2p doesn't yet
     support calling external PNG optimizers and converting their output to
     PDF.

Q57. Does sam2p convert images to canonical form, i.e. if I have two
     source images with identical width, height and RGB8 pixel
     representation, and I convert both with sam2p with the same flags,
     will the two output image files be byte-by-byte identical?

A57. Yes, since version 0.46-2.

     The only code code needed for that was sorting the indexed palette.

     For blackbox input images which sam2p doesn't decompress (e.g. JPEG
     with /Compression/JAI), the output is only guaranteed to be
     byte-byte-byte identical, if the input was byte-byte-byte identical.

Q58. Can sam2p generate a PDF which is scaled proportionally (i.e. keeping
     the aspect ratio) to a specified page size, and centered on the page?

A58. No, but the Perl script sam2p_pdf_scale.pl bundled with sam2p can
     post-process the file created by sam2p. For example, to scale and
     center a PDF on an A4 paper, do:

       $ sam2p input.img output.pdf
       $ sam2p_pdf_scale.pl 595 842 output.pdf

     Please also have a look at the LaTeX package pdfpages.sty for more
     options. It can also be used to concatenate multiple PDFs.
     Its documentation:
     http://www.ctan.org/get/macros/latex/contrib/pdfpages/pdfpages.pdf

     Example output.tex file:

       \documentclass{article}
       \pdfcompresslevel9
       \paperwidth 21cm    \pdfpagewidth\paperwidth
       \paperheight29.7cm  \pdfpageheight\paperheight
       \usepackage{pdfpages}
       \begin{document}
       \includepdf{output_tmp.pdf}
       \end{document}

     How to compile the .tex file above:

       $ sam2p input.img output_tmp.pdf
       $ pdflatex output.tex

     Please note that a2ping.pl or pdftk won't work either.

Q59. How does sam2p detect the bounding box of PostScript and EPS input?

A59. For PostScript input, the paper size specified in the PostScript code
     is used, reverting to the system's default paper size if missing.
     PostScript input is detected by finding `%!PS-Adobe-' at the beginning
     of the file, but `EPSF-' missing from the first line. Paper size can be
     specified in the PostScript code using `<</PageSize[...]>> setpagedevice', 'a4', `letter' etc.
     The comments `%%BoundingBox:' etc. are ignored.

     For EPS input, the `%%ExactBoundingBox:' is used, reverting to
     `%%HiResBoundingBox:', reverting to `%%BoundingBox:', reverting to the
     system's default paper size. The paper size specified in the PostScript
     code is ignored. EPS input is detected by finding `%!PS-Adobe-' at the
     beginning of the file and `EPSF-' in the first line. When converting to
     PostScript, EPS or PDF, the (in.llx, in.lly) coordinates of the input
     bounding box are not preserved: the output file will always have (0, 0)
     as its lower left corner and (in.urx-in.llx, in.ury-in.lly) as its
     upper right corner.

Q60. When compiling sam2p, the ./configure command prints an error:
     ``running make Makedep... error configure: error: cannot compute depends''

A60. Please download the newest sam2p:

         $ git clone https://github.com/pts/sam2p

     , and run ./configure again. If it still
     fails, please report the issue on https://github.com/pts/sam2p/issues ,
     and attach the config.log file generated by ./configure to your report.

     Some more detailed analysis: ./configure runs `make Makedep', which
     runs `perl -x -S ./ccdep.pl --FAL=assert,no,yes,checker g++', which
     runs g++ to analyze the dependencies between .cpp files, and analyzes
     the error and warning messages printed by g++. Newer versions of g++
     (and clang++, which is typically run instead of g++ on macOS) tend to
     print more warnings, which ccdep.pl doesn't understand, and fails.

     Work is being done to make ccdep.pl more resilient
     (#5).

Q61. What is lzw_codec and how does sam2p use it?

     lzw_codec is an external program which can do LZW compression and
     decompression. If sam2p is configured with --enable-lzw (default), then
     it uses a built-in LZW compressor (and it doesn't use lzw_codec). If
     sam2p is compiled with --disable-lzw, then it uses lzw_codec for LZW
     compression (and fails if not installed).

     If in doubt, then you don't need lzw_codec to do LZW compression with
     sam2p): just use the built-in LZW compressor by default.

     lzw_codec is available from https://github.com/pts/lzw_codec .

Standards
~~~~~~~~~
-- PSL1 is PostScript LanguageLevel1, as defined by Adobe's PostScript
   Language Reference Manual.
-- PSLC is PSL1 with the CMYK extension (including the `colorimage'
   operator). Supersedes PSL1.
-- PSL2 is PostScript LanguageLevel2, as defined by Adobe's PostScript
   Language Reference Manual. Supersedes PSLC.
-- PSL3 is PostScript LanguageLevel3, as defined by Adobe's PostScript
   Language Reference Manual (PLRM.pdf). Supersedes PSL2.
-- PDF1.0 is PDF version 1.0, as defined by Adobe's PDF Reference.
-- PDF1.1 is PDF version 1.1, as defined by Adobe's PDF Reference.
   Supersedes PDF1.0.
-- PDF1.2 is PDF version 1.2, as defined by Adobe's PDF Reference.
   Supersedes PDF1.1.
-- PDF1.3 is PDF version 1.3, as defined by Adobe's PDF Reference.
   Supersedes PDF1.2.
-- PDF1.4 is PDF version 1.4, as defined by Adobe's PDF Reference
   (PDFRef.pdf). Supersedes PDF1.3.
-- PDF1.5 is PDF version 1.4, as defined by Adobe's PDF Reference
   (PDFRef.pdf). Supersedes PDF1.4.
-- PBM is Portable Bitmap file format, as defined in NetPBM's pbm(5) UNIX
   manual page.
-- PGM is Portable Graymap file format, as defined in NetPBM's pgm(5) UNIX
   manual page.
-- PPM is Portable Pixmap file format, as defined in NetPBM's ppm(5) UNIX
   manual page.
-- PNM is Portable Anymap file format, as defined in NetPBM's pnm(5) UNIX
   manual page. It is the union of PGM, PPM and PPM.
-- PAM is the new, Portable ...map file format, as defined in NetPBM's pam(5)
   UNIX manual page. We don't support it yet.
-- TIFF is ... v6.0.
-- JPEG is baseline JPEG JFIF file format as defined by the Joint Picture
   Expert Group.
-- PNG is Portable Network Graphics file format v1.0, as defined by
   RFC 2083.

Compatibility notes
~~~~~~~~~~~~~~~~~~~
by pts@fazekas.hu at Wed Nov 14 12:14:15 CET 2001
Fri Mar 22 11:48:36 CET 2002
Sat Apr 20 19:57:44 CEST 2002
Fri Feb  7 11:15:39 CET 2003

-- Ghostscript 6.50 has problems with /FileFormat/PDFB1.0
   /SampleFormat/JAI|/IJG/DCT
   (Error: /syntaxerror in ID). The problem has been fixed in Ghostscript
   7.04. With the buggy Ghostscript use /FileFormat/PDF1.0 instead.
-- /FileFormat/PDF[B]1.0 /SampleFormat/Mask|/Indexed1 doesn't
   work on Acrobat Reader 5.0 on Linux: a fully opaque, one-color rectangle is
   painted. This works fine on gs 6.50 and xpdf 1.0, so Acrobat Reader is
   assumed to be buggy.
-- The GIMP 1.0 cannot load PlanarConfig Separated TIFF images of type
   GrayA. (But can load PlanarConfig Contiguous GrayA.)
-- xv cannot display gray TIFF images with transparency.
   xv: Sorry, can not handle 2-channel images.
-- (lib)tiff FAX compression an PS /CCITTFaxEncode have black and white the
   opposite way. So `/CCITTFaxEncode <</BlackIs1 true>>' has to be applied
   when creating a TIFF file.
-- libtiff 3.5.4 doesn't read or write an indexed image with transparency:
   Sorry, can not handle contiguous data with PhotometricInterpretation=1,
   and Samples/pixel=2. (Doesn't work with convert or GIMP.)
-- libtiff 3.5.4 doesn't read or write a gray with transparency:
   Sorry, can not handle contiguous data with PhotometricInterpretation=2,
   and Samples/pixel=2. (Doesn't work with convert, works with GIMP.)
-- libtiff doesn't read or write TIFFTAG_SUBFILETYPE/FILETYPE_MASK +
   TIFFTAG_PHOTOMETRIC/PHOTOMETRIC_MASK. One has to use TIFFTAG_EXTRASAMPLES
   instead.
-- libtiff (and the TIFF file format) supports only /Predictor 1 and
   /Predictor 2, with /Compression/LZW and /Compression/ZIP.
-- libtiff supports only bpc=8 and bpc=16 with /Predictor 2
-- libtiff and most TIFF-handling utils have buggy support for TIFF/JPEG.
   See FAQ answer Q4.
-- libtiff supports only files with all components having the same
   BitsPerSample.
-- acroread 4.0 can display all possible /Predictor values with /Indexed1.
-- Ghostscript 5.50 renders (PDF?) images inaccurately: the last bit of
   the 8-bit palette sometimes gets wrong.
-- Netscape Navigator 4.7 displays transparent PNG images with their bKGD
   (or an arbitrary color if bKGD not present) as a solid background. This
   is a bug.
-- pdftops 0.92 has serious problems displaying images if /Predictor != 1.
   The image will be obscured without an error message. Ghostscript 5.50 and
   Acrobat Reader 4 do not have such problems.
-- Ghostscript 5.50 cannot display a PDF with /ColorSpace[/Indexed/DeviceRGB
   ...]. Acrobat Reader 4, Ghostscript 7.04 and pdftops 0.92 can.
-- /Decode is not required in PDF.
-- GIMP 1.0 completely ignores the PNG tRNS chunk! (Thus it won't recognise
   such a transparency in PNG.) Use `pngtopnm -alpha' instead!
-- pngtopnm honors the PNG bKGD chunk only if called as `pngtopnm -mix'
   (and does mixing)
-- convert honors the PNG bKGD chunk (and does mixing)
-- display doesn't honor the PNG bKGD chunk, but has `-bg' command line option
-- xv honors the PNG bKGD chunk (and does mixing)
-- PDF procsets (subsection 8.1 of PDFRef.pdf)
   /PDF
   /Text
   /ImageB Grayscale images or image masks
   /ImageC Color images
   /ImageI Indexed (color-table) images
-- Ghostscript always requires the /Decode entry in image dicts
-- /DCTEncode and /DCTDecode supports only BitsPerComponent==8.
-- Actually PostScript supports 1,2,4,8,12 BitsPerComponent. PDF1.3 supports
   only 1,2,4,8. We support only 1, 2, 4 and 8.
-- PostScript also supports the CMYK color space, not just gray and RGB.
   (And also the HSB, which can be transformed to RGB in an ugly way.)
-- PostScript supports PNG predictors to enhance compression.
-- The PLRM 4.10.6 describes a trick with patterns and imagemask to do
   transparent images. Unfortunately this doesn't work in Ghostscript 5.50
   and xpdf 0.92 (but it works in acroread 4.0), so we don't use it. That's
   why we have only two *-transparent-* entries.
-- ImageMagick EPSI is an EPS with preview (%%BeginPreview .. %%EndPreview)
-- ImageMagick EPSF and EPS are equivalent
-- ImageMagick EPS* is incredibly slooow because of the bad design, even for
   LanguageLevel 2.
-- ImageMagick EPS* cannot display color images without the colorimage
   opertor. (We could do some trickery with multiple calls to imagemask.)
-- tiff2ps cannot display color images without the colorimage
   opertor. (We could do some trickery with multiple calls to imagemask.)
-- Timing: 1495 x 935 RGB, gs -sDEVICE=bmp16m -sOutputFile=/dev/null
   time gs -q -sDEVICE=ppmraw -sOutputFile=t.ppm $IN.eps </dev/null
   ImageMagick 6620 ms user
   tiff2ps-readhexstring 2320 ms user
   currentfile-colorimage 2120 ms user
   readstring-colorimage 2170 ms user
   currentfile-/FlateDecode-colorimage 2670 ms user
-- There is a NullEncode filter, but NullDecode doesn't exist
-- speed conclusions:
   1. Use currentfile as data source (LanguageLevel2) if possible.
   2. /FlateDecode adds a 25% speed penalty. But it compresses quite well,
      so use it!
-- PostScript LanguageLevel2 supports the indexed color space:

	/colormap colors 3 mul string def
	currentfile colormap readhexstring pop pop
	[ /Indexed /DeviceRGB colors 1 sub colormap ] setcolorspace

-- EPS comments: (ImageMagick)

	%%DocumentData: Clean7Bit
	%%LanguageLevel: 1

-- PSL1/PSL2 supports the following color setting operators: (all operands
   are between 0.0 and 1.0)

	<num> setgray  currentgray % PSL1, 0.0=black 1.0=white
	<hue> <saturation> <brightness> sethsbcolor % PSL1
	<red> <green> <blue> setrgbcolor % PSL1
	<cyan> <magenta> <yellow> <black> setcmykcolor % PSL2; not in PSL1

__END__