MATLAB Answers

Comparing Jpeg of images with different size and resolution?

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Paolo Piazza
Paolo Piazza on 27 May 2020
Commented: Rik on 2 Sep 2020
Hi everyone,
for a project I need to compare the jpeg size of different images. The problem is that sometimes I have Images that I need to crop (I need only a particular area of the page and not the rest). So basically, I need to crop, resize and also adjust images and compare their jpeg size. Is it feasible to do it with matlab? or would I obtain biased results?
thanks in advance
  3 Comments
Rik
Rik on 27 May 2020
I would be really careful. If I recall correctly simply loading and saving with Matlab can change the values that are stored in a jpeg.

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Answers (1)

Pratheek Punchathody
Pratheek Punchathody on 2 Sep 2020
Hi,
"size()" function will return number of pixel rows, number of pixel columns and number of colour channels present in the image.
%%Code starts here
%%testimage1.jpg and testimage2.jpg are the sample data
Imx = imread('testimage1.jpg');
Im2 = imread('testimage2.jpg');
%%crop testimage1.jpg
Im1 = imcrop(Im1,[75 68 130 112]);
[rowspx1 columnpx1 noColorChannels1] = size(Im1);
[rowspx2 columnpx2 noColorChannels2] = size(Im2);
if rowspx1 * columnpx1 == rowspx2 * columnpx2
disp("Testimages have same number of pixels");
elseif rowspx1 * columnpx1 > rowspx2 * columnpx2
disp("testimage1.jpg has larger number of pixels");
else
disp("testimage2.jpg has larger number of pixels");
end
%Code ends here
Please find more information for cropping the image please check this link
  1 Comment
Rik
Rik on 2 Sep 2020
That isn't the question. The question was about meaasuring the file size for a fixed image size. That way you can measure the compression, which is inversely correlated with the image complexity.

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