MATLAB: How to know the size of a quantized image

Image Processing Toolboximage sizequantize

I designed a simple uniform quantizer, it is a part of project, I used 'leena.jpg' image the original size is about 65.8 KB, after running this code:
img = imread('leena.jpg');
figure(1)
imshow(img)
[m,n] = size(img);
M = 8; K = 256/M;
for i = 1:m
      for j = 1:n
          quant_img(i,j) = floor(img(i,j)/K) * K + (K/2);
      end
end
figure(2)
imshow(quant_img)
—————–
It is clear the image quality reduced, but when I save the two figures (the original and the quantized) as jpg format, I got 14.4 KB for the original and 16.5 KB for the quantized image! When I increase the number of levels (M = 32) the size decrease to 14.8 KB! Why the size of the image is decreasing with increasing the number of levels!! It should be the reverse, right?

Best Answer

It's a moot question because you should not even be using jpg. Use PNG instead. It will be bigger but at least you won't have JPG artifacts because it's lossless compression, and pretty much the new standard that most people use.
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