Dang, just almost remembered removing this duplicate (56-p6=binary.pnm). Rev: 1x1/57-binary.pnm:1.2(DEAD)
Added some more test images, not all of which encode colour information. Rev: 1x1/49.svg:1.1 Rev: 1x1/50.xbm:1.1 Rev: 1x1/51-p1.pnm:1.1 Rev: 1x1/52-p2.pnm:1.1 Rev: 1x1/53-p3=ascii.pnm:1.1 Rev: 1x1/54-p4.pnm:1.1 Rev: 1x1/55-p5.pnm:1.1 Rev: 1x1/56-p6=binary.pnm:1.1 Rev: 1x1/57-binary.pnm:1.1 Rev: 1x1/58.pvr:1.1