PERFORMANCE OF COMPRESSION RATIO (CR ) IN JPEG

helo every one

i need to find comnpression ratio and performance of jpeg

i do jpeg compression for gray lena image , i have the

cr = numel of original/ numel of compress

performance% =(100-((1/cr)*100))

i get 43.6%

it not good why? .or my eq error

Answer 1

[Rahul]

Hi @eng m,

In order to achieve the desired result, consider using 'imfinfo' function to read the compressed image and original image. The 'FileSize' property of the struct obtained after using this function can give desired results in terms of compression ratio performance. Here is an example:

compressedImageInfo = imfinfo('lena_compressed.jpg');
compressedSize = compressedImageInfo.FileSize;
% The 'compressedSize' value can be used in place of numel(compressedImage) in the given formula

The following MATLAB Answers also give insights regarding compression ratio calculation:

https://www.mathworks.com/matlabcentral/answers/27322-cr-bit-per-pixel-image-compression

https://www.mathworks.com/matlabcentral/answers/237620-how-to-calculate-image-compression-ratio

Refer to the following MathWorks documentations to know more:

'imfinfo': https://www-test1.mathworks.com/help/releases/R2018a/matlab/ref/imfinfo.html

Thanks.