Suitable method for image comparison

What is suitable method for image comparison ? I want to compare 2 images which both in canny's algorithm stage. I prefer a simple one which i can apply it in my GUI. if there any guide or link please give me. Need your help guys. thanks.

Answer 1

[Image Analyst]

I don't think there is any simple way. Sorry.

You can look at how they compare images in CBIR (Content based Image Retrieval) where they compare the outputs of SIFT or SURF algorithms. I don't think any of those algorithms could be called "simple".

[Akmal Rahmat]

Sorry for my words before. how about similarity measure ?

[Image Analyst]

A very common similarity measurement is SSIM http://en.wikipedia.org/wiki/Structural_similarity