Finding Duplicate & Almost Duplicate Photo Fies

There are lots of programs out there that do a good job of finding identical duplicate files. The problem of dealing with duplicate images is more more difficult as we need to deal with the same image in different file formats, the same image in the same format that has been slightly edited, the same image that has been cropped, and even several very close variants of the same picture.

I have not been able to find any good program that handles these specific photo problems but there has to be something out there that will work.

Any ideas or suggestions for programs that I can try would be appreciated.

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Don