Patents are not only about processes, they can also cover the final product amongst other aspects. The patent in question also does the same [1], as visible via claims 14, 29, 46, 51, whereas the claim 1 is about the "method".

Reading the claim #1 of the said patent, I do not find it "very specific" as you said. It is quite broad within the purposes of making a mosaic image. One way of avoiding infringing claim 1 is to not use a computer for this.

I agree that the Wikipedia page mentions multiple programs doing this for long, however, it has not committed that there has no patent violation and a possibility that the patent holder "has chosen not to bring infringement proceedings" is also cited.

[1] https://worldwide.espacenet.com/patent/search/family/0267124...