I work in the same market as Lyst, and can say for a fact that the images variations we get from clients even from renowned fashion houses is huge. By variations I mean compression, quality, subject's clarity and the list just goes on...

A good algorithm would surely solve part of the problem, but given the imagery non-uniform patterns a great deal of resources (engineering skills + computing power) would likely be required. Given Lyst's recent VC rounds maybe they can afford that, but I surely cannot.

So I went for the poor-man option: https://gist.github.com/mvsantos/5554663

(I'm definitely bookmarking the link you suggested and also the one suggested by sjtgraham.)