[adgjlsfhk1]

Writing an encoder for that sounds like a nightmare though. Also the speed would suck since you would have unpredictable memory accesses.

[meltedcapacitor]

An encoder just walking a regular spiral (no uniform bands detection) is not hard. The band thing is an accidental artefact of the idea but plain run length encoding probably already captures most of the effect so no imperative to actually implement it.

Speed, yes, it is a fair objection, until hardware adopts spiral encoding :-)