Comparing Jpeg of images with different size and resolution?

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

[Rik]

What is the exact comparison you would like to perform?

[Paolo Piazza]

Basically some researchers used the jpeg size as a measure for the complexity of an image. I just want to find a way to measure the jpeg size without creating any bias in my results.

[Rik]

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.

Answer 1

[Pratheek Punchathody]

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

[Rik]

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.