tif2bjpeg.m

jpg compression and decompression~

function fsize=tif2bjpeg(filename, fileOut, quantLevels, ...
    dilateAmount, targetSize)
%
% fsize=tif2bjpeg(filename, quantLevels, dilateAmount)
%
% Uses the image in TIFF file to create a BJPEG file (edge enhanced
% JPEG file).  QuantLevels are the number of quantization levels to
% use on the edge error information, and dilateAmount is the the
% amount of dilation to use when generating the edge mask.  targetSize
% is the size the total JPEG+mask image should take when stored.
% fileOut is the name to save the rendered BJPEG file in (JPEG at
% highest quality).
%

% load the good image
[rImage gImage bImage] = tiffread(filename);

% display the image
displayImage(rImage, gImage, bImage);

% Generate the Y plane of the image
yImage =   0.2990*rImage + 0.5870*gImage + 0.1140*bImage;

% display the Y plane
figure;
displayImage(yImage);

% get the edge image and dilate
bwEdgeImage=edge(yImage, 'prewitt');
seMatrix=ones(dilateAmount);
bwEdgeImage=dilate(bwEdgeImage, seMatrix);
figure;
displayImage(double(bwEdgeImage));

% loop until we get our file size below the target
continue=1;
acc=0;
fsize=targetSize;
while continue
  
  % create the bad image
  jpSize=createJpeg(fileOut, rImage, gImage, bImage, fsize);
  [rImageBad gImageBad bImageBad] = jpgread(fileOut);
  
  % Generate the Y, Cr and Cb planes of the bad image
  yImageBad =   0.2990*rImageBad + 0.5870*gImageBad + 0.1140*bImageBad;
  cbImageBad = -0.1687*rImageBad - 0.3313*gImageBad + 0.5000*bImageBad;
  crImageBad =  0.5000*rImageBad - 0.4187*gImageBad - 0.0813*bImageBad;
  
  % the error between good and bad Y planes in edge regions 
  edgeInfoErrorImage=double(bwEdgeImage).*(yImage-yImageBad);
  
  % find the mask size
  mSize=maskSize(edgeInfoErrorImage, quantLevels);
  fsize=mSize+jpSize
  targetSize
  
  % continue if total file size still is too big
  if fsize < targetSize
    continue=0;
  else
    fsize=targetSize-mSize-acc;
    acc=acc+250;
  end;
  
end;

% display the bad image
figure;
displayImage(rImageBad, gImageBad, bImageBad);

% display the bad Y plane
figure;
displayImage(yImageBad);

% quantize the edge error
edgeInfoErrorImage=round((quantLevels-1)*((edgeInfoErrorImage+1)/2));
edgeInfoErrorImage=(edgeInfoErrorImage/(quantLevels-1))*2-1;
edgeInfoErrorImage=edgeInfoErrorImage.*double(bwEdgeImage);

% now add in our error Y image stuff
yImageNew=edgeInfoErrorImage+yImageBad;
figure;
displayImage(yImageNew);

% combine new yImage back with color planes
rImageNew = truncate(yImageNew + 1.4020*crImageBad,0,1);
gImageNew = truncate(yImageNew - 0.3441*cbImageBad - 0.7141*crImageBad,0,1);
bImageNew = truncate(yImageNew + 1.7720*cbImageBad - 0.0001*crImageBad,0,1);

% display new image
figure;
displayImage(rImageNew, gImageNew, bImageNew);
jpgwrite(fileOut, rImageNew, gImageNew, bImageNew, 100);