Written and Read Image files are different..?

Please see the below program...

A=imread('gapi.jpg');
imwrite(A,'enc.jpg');
B=imread('enc.jpg');
isequal(A,B);

After running the above program , it returns the value 0 , indicating that A and B are not equal. But are they the same images?? Why is it different?? Please help me

How can I overcome this, so that the read image files is exactly equal to the written image ???

Answer 1

[Image Analyst]

Of course not. This is because you're using a lossy compression scheme: JPEG. The way that MATLAB compresses the image may not be the same that some other program compressed your original image. Don't use JPG anyway. Use PNG format. It's lossless compression and you won't have any of these problems.

[Ananthu S]

Ok.. I got it.. BMP also would work fine, right?

[Image Analyst]

Yes it would.

[Walter Roberson]

In particular, JPEG will change depending upon the compression parameters that were set. Different programs have different default settings for what JPEG calls "quality"