Add commands 7

Author: timerring

17_common_image_processing_commands_in_Matlab_(7).md

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+- [Matlab常用图像处理命令108例（七）](#matlab常用图像处理命令108例七)
+  - [86.pixval](#86pixval)
+  - [87.qtdecomp](#87qtdecomp)
+  - [88.qtgetblk](#88qtgetblk)
+  - [89.qtsetblk](#89qtsetblk)
+  - [90.radon](#90radon)
+  - [91.rgb2gray](#91rgb2gray)
+  - [92.rgb2hsv](#92rgb2hsv)
+  - [93.rgb2ind](#93rgb2ind)
+  - [94.rgb2ntsc](#94rgb2ntsc)
+  - [95.rgb2ycbcr](#95rgb2ycbcr)
+  - [96.rgbplot](#96rgbplot)
+  - [97.roicolor](#97roicolor)
+
+
+# Matlab常用图像处理命令108例（七）
+
+## 86.pixval
+
+功能：显示图像像素信息。
+语法： 
+
+```matlab
+pixval on pixval off pixval
+pixval(fig,option) 
+```
+
+相关命令： impixel, improfile
+
+## 87.qtdecomp
+
+功能：进行四叉树分解。
+语法： 
+
+```matlab
+S = qtdecomp(I)
+S = qtdecomp(I,threshold)
+S = qtdecomp(I,threshold,mindim)
+S = qtdecomp(I,threshold,[mindim maxdim]) 
+S = qtdecomp(I,fun)
+S = qtdecomp(I,fun,P1,P2,...)
+```
+
+举例 
+
+```matlab
+I = [1 1 1 1 2 3 6 6
+1 1 2 1 4 5 6 8
+1 1 1 1 10 15 7 7
+1 1 1 1 20 25 7 7
+20 22 20 22 1 2 3 4
+20 22 22 20 5 6 7 8
+20 22 20 20 9 10 11 12
+22 22 20 20 13 14 15 16];
+S = qtdecomp(I,5); full(S)
+ans =
+4 0 0 0 2 0 2 0
+0 0 0 0 0 0 0 0
+0 0 0 0 1 1 2 0
+0 0 0 0 1 1 0 0
+4 0 0 0 2 0 2 0
+0 0 0 0 0 0 0 0
+0 0 0 0 2 0 2 0
+0 0 0 0 0 0 0 0
+```
+
+相关命令： 
+qtgetblk, qtsetblk
+
+## 88.qtgetblk
+
+功能：获取四叉树分解中的块值。
+语法： 
+
+```matlab
+[vals,r,c] = qtgetblk(I,S,dim) 
+[vals,idx] = qtgetblk(I,S,dim) 
+```
+
+举例 
+
+```matlab
+[vals,r,c] = qtgetblk(I,S,4)
+vals(:,:,1) = 1 1 1 1
+1 1 2 1
+1 1 1 1
+1 1 1 1
+vals(:,:,2) = 20 22 20 22
+20 22 22 20
+
+20 22 20 20
+22 22 20 20
+r = 1
+5
+c = 1
+1
+```
+
+相关命令： 
+qtdecomp, qtsetblk
+
+## 89.qtsetblk
+
+功能：设置四叉树分解中的块值。
+语法： 
+
+```matlab
+J = qtsetblk(I,S,dim,vals)
+```
+
+举例 
+
+```matlab
+newvals = cat(3,zeros(4),ones(4)); 
+J = qtsetblk(I,S,4,newvals)
+J =
+0 0 0 0 2 3 6 6
+0 0 0 0 4 5 6 8
+0 0 0 0 10 15 7 7
+0 0 0 0 20 25 7 7
+1 1 1 1 1 2 3 4
+1 1 1 1 5 6 7 8
+1 1 1 1 9 10 11 12
+1 1 1 1 13 14 15 16
+```
+
+相关命令： 
+qtdecomp, qtgetblk
+
+## 90.radon
+
+功能：计算Radon变换。
+语法： 
+
+```matlab
+R = radon(I,theta) 
+R = radon(I,theta,n) 
+[R,xp] = radon(...) 
+```
+
+举例 
+
+```matlab
+iptsetpref('ImshowAxesVisible','on')
+I = zeros(100,100); 
+I(25:75,25:75) = 1;
+theta = 0:180;
+[R,xp] = radon(I,theta);
+imshow(theta,xp,R,[]), colormap(hot), colorbar
+```
+
+![](https://raw.githubusercontent.com/timerring/scratchpad2023/main/2023/03/11-22-59-29-1678546764.png)
+
+相关命令： 
+iradon, phantom
+
+## 91.rgb2gray
+
+功能：转换RGB 图像或颜色映像表为灰度图像。
+语法： 
+
+```matlab
+I = rgb2gray(RGB) 
+newmap = rgb2gray(map) 
+```
+
+相关命令： 
+ind2gray, ntsc2rgb, rgb2ind, rgb2ntsc
+
+## 92.rgb2hsv
+
+功能： 
+转化RGB值为HSV颜色空间。
+语法： 
+
+```matlab
+hsvmap = rgb2hsv(rgbmap) 
+HSV = rgb2hsv(RGB)
+```
+
+相关命令： 
+hsv2rgb, rgbplot
+
+## 93.rgb2ind
+
+功能：转化RGB图像为索引图像。
+语法： 
+
+```matlab
+[X,map] = rgb2ind(RGB,tol) 
+[X,map] = rgb2ind(RGB,n) 
+X = rgb2ind(RGB,map)
+[...] = rgb2ind(...,dither_option)
+```
+
+举例 
+
+```matlab
+RGB = imread('flowers.tif'); 
+[X,map] = rgb2ind(RGB,128); 
+imshow(X,map)
+```
+
+![](https://raw.githubusercontent.com/timerring/scratchpad2023/main/2023/03/11-22-59-40-1678546776.png)
+
+相关命令： 
+cmunique, dither, imapprox, ind2rgb, rgb2gray
+
+## 94.rgb2ntsc
+
+功能：转化RGB的值为NTSC颜色空间。
+语法： 
+
+```matlab
+yiqmap = rgb2ntsc(rgbmap) 
+YIQ = rgb2ntsc(RGB)
+```
+
+相关命令： 
+ntsc2rgb, rgb2ind, ind2rgb, ind2gray
+
+## 95.rgb2ycbcr
+
+功能：转化RGB的值为YcbCr 颜色空间。
+语法： 
+
+```matlab
+ycbcrmap = rgb2ycbcr(rgbmap) 
+YCBCR = rgb2ycbcr(RGB)
+```
+
+相关命令： 
+ntsc2rgb, rgb2ntsc, ycbcr2rgb
+
+## 96.rgbplot
+
+功能：划分颜色映像表。
+语法： 
+
+```matlab
+rgbplot(map) 
+```
+
+![](https://raw.githubusercontent.com/timerring/scratchpad2023/main/2023/03/11-22-59-57-1678546792.png)
+
+举例rgbplot(jet)
+
+## 97.roicolor
+
+功能：选择感兴趣的颜色区。
+语法： 
+
+```matlab
+BW = roicolor(A,low,high) 
+BW = roicolor(A,v)
+```
+
+举例 
+
+```matlab
+I = imread('rice.tif');
+BW = roicolor(I,128,255); 
+imshow(I);
+figure, imshow(BW)
+```
+
+![](https://raw.githubusercontent.com/timerring/scratchpad2023/main/2023/03/11-23-00-07-1678546804.png)
+
+相关命令： roifilt2, roipoly
+
+
+
+参考文献：
+
+[1] [Rafael C. Gonzalez, Richard E. Woods, and Steven L. Eddins. 2003. Digital Image Processing Using MATLAB. Prentice-Hall, Inc., USA.](https://github.com/timerring/digital-image-processing-matlab/blob/main/reference/Digital_Image_Processing_Using_Matlab.pdf)
+
+[2] [阮秋琦. 数字图像处理（MATLAB版）[M]. 北京：电子工业出版社, 2014.](https://github.com/timerring/digital-image-processing-matlab/blob/main/reference/Digital_Image_Processing_(MATLAB_version).pdf)
+
+[3] [冈萨雷斯. 数字图像处理（第三版）[M]. 北京：电子工业出版社, 2011.](https://github.com/timerring/digital-image-processing-matlab/blob/main/reference/Digital_Image_Processing_(Third_Edition).pdf)
+
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