improved speed by not converting to a cell array of strings but doing…

… all operations on string arrays

helperFunctions/prepBMP.m

@@ -16,7 +16,7 @@
 numOfBytes = dec2hex(typecast(uint32(size(BMP1,1)*size(BMP1,2)*...
     bitDepth),'uint8'),2);
 backgroundColor = ['00'; '00'; '00'; '00'];
-compression = '00';
+compression = '02';
 
 header = [signature; imageWidth; imageHeight; numOfBytes; ...
     'FF'; 'FF'; 'FF'; 'FF'; 'FF'; 'FF'; 'FF'; 'FF'; backgroundColor; ...
@@ -28,19 +28,19 @@
 BMP1 = BMP1'*1; 
 
 % expand to 24bit in 3x8bit decimal notation
-BMP24 = cellstr(dec2hex(BMP1(:),6));
+BMP24 = dec2hex(BMP1(:),6);
 
 % clear return variable
 data = '';
 
 % % compress if whished
 if strcmp(compression, '02')
     % reshape in order to get 24bit pixel information line by line
-    BMP24 = reshape(BMP24, size(BMP1,1), [])';
-    for i = 1:size(BMP24,1)
-        [~, ~, ic] = unique(BMP24(i,:));
-        ind = find(diff([ic(1)-1, ic(:)']));
-        relMat = [formatRep(diff([ind, numel(BMP24(i,:))+1])), cell2mat(BMP24(i,ind)')];
+    [szy, szx] = size(BMP1);
+    for i = 1:szx
+        [~, ~, ic] = unique(BMP24((i-1)*szy+1:i*szy,:), 'rows');
+        ind = find(diff([ic(1)-1, ic(:)']))+(i-1)*szy;
+        relMat = [formatRep(diff([ind, i*szy+1])), BMP24(ind,:)];
         data = [data sprintf(relMat(:,:)')];
     end
     % put together header, compressed data and end of image padding