it does, it just works on estimates of percepts rather than bits.
you can think of a perceptual hash as two functions. a perceptual function that maps differing collections of bits that appear the same or similar to the same bits, and then a traditional hash function to ensure that these intermediate values get shuffled.
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Perceptual hashing wouldn't seem to satisfy your second requirement there, either.
it does, it just works on estimates of percepts rather than bits.
you can think of a perceptual hash as two functions. a perceptual function that maps differing collections of bits that appear the same or similar to the same bits, and then a traditional hash function to ensure that these intermediate values get shuffled.