PBase

I looking for a photo software program that is capable of determining when two photos are different from each other. I have a huge database of jpg images which were collected by taking a photo of the same scene every two minutes over a long period of time. I would like to be able to compare photos sequentially with a program that will indicate when side by side photos (ie. a photo taken at 2min and at 4min) are different. Does anyone know of a program that can do this or know of someplace else to look? Any help is greatly appreciated.