Has NetFree looked into using neural networks to approve pictures?
It sounds impossibly sci-fi that an algorithm can automatically and accurately do the kind of image filtering that NetFree requires, but it seems to me that it is actually possible with today's technology and relatively straightforward to do.
Feeding the algorithm with a set of input pictures and simple output values, such as NetFree's current image database, and later using the algorithm to guess the correct value for an unseen picture, sounds like quite a classic use case for neural networks.
Since neural networks are probability based, they could be used for example, over 60% suspicion: auto block. under 10%: auto allow. everything else filtered by humans and used to continue training of the network. This will dramatically decrease the load on NetFree's staff, and the percentages can be tweaked when and if confidence in the algorithm increases.