who could testify an image is photoshopped?

I am helping a friend through a messy divorce and her husband and the husband just released 'evidence' that includes a bunch of photoshopped images. Which is really a godsend for us because once we prove they are photoshopped his credibility is going to plummet.

i have looked at the photos myself and they are clearly photoshopped, I can recognize the signs, so I know it wouldn't be hard to get others to agree. However, I'm a friend who's only credentials with photoshop is "I'm a geek and you sort of run into it", which is hardly enough to make me a legally trusted authority that the judge would listen to.

So while I know they are photoshopped...what is the best way to *prove* that to a judge such that he will have no doubt at all of the validity of the statement?