Everyone does this to match files as identical, be it sha, md5, or something else. I cannot imagine any other method such that it would first come to mind easily you would be doing to check if two files are the same.

I don't mean to offend but I quite literally mean everyone does this. Every software updater, game patcher, checking if two binary files are identical (pixel perfect/lossless in this case: BMP, PNG created by same encoder off same inputs would qualify, JPG would likely not), all of them do exactly this.

GPT-Analysis or a similarity and image chunk hashing would not be the first thing you turn to if what you wanted was exact identical pixel perfect. I am curious what your background is if this is the case.