data loss in jpeg

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naval solanki
naval solanki on 13 Feb 2017
Commented: DGM on 5 Feb 2023
how much data loss (in %) image compression method the 'JPEG'

Accepted Answer

Walter Roberson
Walter Roberson on 13 Feb 2017
JPEG can be configured between no data loss and 99% data loss.
See the imwrite() 'quality' parameter, and 'mode', 'lossless'
  1 Comment
DGM
DGM on 5 Feb 2023
For passers-by, I should note that setting the 'quality' parameter to 100% does not make the process lossless.
% generate a small synthetic image with flat regions and hard edges
inpict = im2uint8(rand(10,10,3));
inpict = imresize(inpict,5,'nearest');
imshow(inpict)
% 100% is the best, right?
fname = 'test.jpg';
imwrite(inpict,fname,'quality',100);
jpegged = imread(fname);
% ... not quite.
imshow(jpegged)
You'd actually have to specify that you want lossless mode, as Walter mentions.
imwrite(inpict,'myfile.jpg','mode','lossless');

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