Compare the pixel of the two different images, takes too long time

Question

I want to compare the pixel of the two different images. I am comparing the pixel of first image with all the pixels of the second Image. Here is my code stuff:

Answer 1

The order of your algorithm is n^4.

I guess that you could drive that down to n^3 if you

1. loop over all possible colors.
2. inside that loop, loop on each image
3. find the occurances of color i in each image
4. finally use an equation to increment Counter

If color i occurs x times in bitmap and y times in bitmap2,

Counter = Counter + x*y