data loss in jpeg

how much data loss (in %) image compression method the 'JPEG'

Answer 1

[Walter Roberson]

JPEG can be configured between no data loss and 99% data loss.

See the imwrite() 'quality' parameter, and 'mode', 'lossless'

https://en.wikipedia.org/wiki/JPEG#JPEG_compression

[DGM]

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');