Clearly better than nothing, but how does it work with perceptual hashes? I gave it five minutes to try to get pHash to run locally but didn't manage to get any useful results from it, I was probably holding it wrong.
The big weakness is that most perceptive hashing algorithms aren’t content aware, so you can easily defeat them by adding or removing background objects that might not be noticed or considered meaningful by a human observer.
Potentially what you could do is generate smaller versions of the images, test their hash matching under different conditions against multiple algorithms and then pick the parameters where you get fewest hash collisions.