Re: CMM "interfering" with PS color picker?
Re: CMM "interfering" with PS color picker?
- Subject: Re: CMM "interfering" with PS color picker?
- From: Chris Murphy <email@hidden>
- Date: Wed, 31 Jan 2001 18:29:24 -0700
It is beyond my comprehension why in the year 2001 this is still a
problem. I understand that different CMM's do different kinds of white
point adaptation and that's the likely cause, but for crying out loud by
*NOW* we should have figured out that 255,255,255 should *always* render
to 0,0,0,0. I mean even the ICC spec says there is no white point
simulation using perceptual, relative colorimetric, saturation intents.
ONLY absolute colorimetric should map source white to destination.
The only thing I can think of is there is a combination "bug" (whatever
you want to call it, it's definitely NOT a feature) between CMM's and
various ICC profiles which makes this so hit or miss. And that Adobe's
engine/CMM has some kind of means of more intelligently mapping
255,255,255 RGB to 0,0,0,0 CMYK.
I don't know if the CMM has the ability to "override" a request by the
profile to map white to something other than white, but if it can, I
don't understand why CMM's have yet to take advantage of this and do the
override on a consistent basis.
At least in Terry's case, going from ProfileMaker 3.1.3 to 3.1.4 solved
the problem, but only in regards to the Adobe CMM. So whose fault is it?
The fact that it's now fixed with the Adobe CMM points to a problem with
ProfileMaker 3.1.3. But both 3.1.3 and 3.1.4 make profiles that cause
something other than 0,0,0,0 CMYK to print with *OTHER* CMMs. That points
to a problem with the CMMs.
This is completely absurd. I really would like someone to explain this to
me.
As noted on another list, this issue with ICC profiles and CMMs mapping
RGB 255,255,255 to something other than 0,0,0,0 CMYK led an advertiser to
refuse to pay for a newspaper ad. Cost was in the five figure range. So
this is potentially a significant problem. (Also it seems to happen only
with 3rd party profiles. Not with ink settings files, or Photoshop
created ICC profiles.)
Chris Murphy