Roger Breton wrote:
I notice some sensible differences between ACE / Adobe CMM and HDM CMM / LittleCMS CMM in Adobe InDesign.
Like, I always end up with more magenta and yellow with ACE?
That's a bit surprising. I know that Adobe have gone to a lot of trouble to ensure numerical accuracy of ACE, and that Marti often cross checks LittleCMS against ACE. There are a few interesting traps for the unwary CMM implementor in in dealing with linear light (ie. RAW) RGB profiles if you create an optimized for speed one step conversion, but that shouldn't usually apply to CMYK. There could be some variation in the nature of the interpolation within the grid (two common choices are simplex (AKA tetrahedral) interpolation and N-linear interpolation. Do you have a specific example ? (ie. profile and the values you were converting ?) Graeme Gill.