To domain switch, slightly: it's essentially a hash bucketing problem in a different guise at that point. The color space and visually distinguishable steps defines your hash bucket count (and kind of an equivalent to a memory limit), and maximally distributing your hashes across the available buckets remains roughly the same problem and you want a relatively well distributed, stable hash for basically the same reasons (color locality versus memory locality).

The perceptual color problem is an interesting "bandwidth" limit on available hash buckets.