CMYK is a bugger to unit test.
$cmyk = new CMYK(0.05, 0.05, 0.05, 0);
$rgb = $cmyk->toRGB()
rgb gives: 242, 242, 242
$rgb->toCMYK() gives 0, 0, 0, 0.05
Pretty much every other implementation of this online seems to do the same, although with photoshop:
CMYK (%): 5, 5, 5, 0
gives:
RGB: 239, 236, 234
and CMYK (%): 0, 0, 0, 5
gives RGB: 241, 242, 242
Grr.
EDITED: 14 Jun 2012 09:51 by MIKEE