Software/Xtra to crop a sequencial images

[viggy]

Hi there
Does any one know about a software or an Xtra that can crop unwanted area of
an image sequence ?
For example - If I have a sequence of images (like a dropdown menu,
highlights etc etc), the software or the Xtra should compare the
sequence and crop them retaining only the changing area of that sequence.
I'm ready to buy it if its not a freeware like "Crop Shop"

Thanks in advance
Viggy