Roberto, Those are all good and puzzling observations? If indeed I choose a grid resolution of 33 for Lab to CMYK, which is the maximum with most profiling software, don't I get 100/(33-1) = 3.125% steps, at best? > I've just realized that 2% in the profiling targets is basically > useless... because it won't be able to make a difference in the > profile itself, due to the grid. > To start with, in typical "non-link" profile usage for separation, the > PCS->device table is used ; that table wastes 70% or so of the space > in colors that are either nonexistent or out of gamut. You wonder why couldn't there be some scaling factor that allows making intelligent use of the encoding space. > If the table > were for example 33 gridpoints in each direction, it's likely that the > "in gamut" colors would extend over less than 15 gridpoints in > average. That would give you about 100/14= 7% steps *if* the device > correlated linearly with PCS space, which of course it doesn't. So > it's more likely to say that you won't have a PCS gridpoint that > renders less than 8-10% in at least one of the device channels. Most CMYK profiles I seen only have 17x17x17 CLUT in the Device -> PCS direction. I was once told that increasing the grid resolution would create monster profiles? > Being that the target has patches with 10% values (and some even 5%), ECI2002 target has patches with 2% values. I'm not following? > the influence of readings from 2% patches will be almost -if not > totally- null. Hmmh? Building flexo profiles with ProfileMakerPro actually yields accurate Device -> PCS mappping, matching the original target measurements. Could it be that the "influence of readings from 2% patches" you refer to is not quite as you think? > Now, if the profile were to be used for proofing (device->PCS) or with > a CMM that does on the fly table reversal (instead of using > pcs->device it just reverses device->PCS) such as argyll, then it's > better. Could you please explain that point further? > But still, to have the 2% patches work in profiling, you'd > need to build a profile with 41 gridpoints (which would give you 2.5% > resolution on device channels), which most profiling packages don't > (argyll does, right?). Please excuse my ignorance, but you mean I could create such profiles with argyll? 41 grid points both ways? > Furthermore, you just can't print 2% on a flexo press that has not > been linearized, at least in the highlights by means of a bump curve. What do you mean roberto? All the flexo printers I know of routinely print 2% dots. Without the need of bump curves. Regards, Roger Breton | Laval, Canada | graxx@xxxxxxxxxxxx http://pages.infinit.net/graxx