Image Difference Detection

Question

I have three images:

I aligned them in a spatio-temporal manner as possible. I want to determine where the differences are in the content (signature, RT logo). A simple image difference (with a subsequent threshold, etc.) does not work here for several reasons:

• The first image is pretty blurry. The difference of the images will give peaks at the edges. I do not want this
• the first image has undergone some color conversion, so the difference contains a lot of information that I do not need.

Here's a simple image difference between the first two images (using GIMP):

Any ideas?

Answer 1

You can split each image into a grid of squares and compute local histograms for each square. Then you can compare the respective histograms with the three images. Histograms that differ from each other should identify the areas with the greatest differences.