[argyllcms] Re: printer profiles - how to get max black

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 06 Dec 2006 23:47:31 +1100

Mike Russell wrote:

I'm successfully making RGB profiles for my printers, using a DTP22,

Is it a DTP22 or a Digital Swatchbook (ie., what's printed on the top
of the instrument ?). I got as far as getting the Digital Swatchbook
that I happen to have working directly with Argyll, although the instrument
refuses to calibrate. I haven't quite finished adding the support for
an instrument that only operates correctly using it's built in switch
though.

One remaining problem - the profiles I create are satisfactory, but for one
of my printers the PCS value for black, Lab(0,0,0), yields an RGB value of
RGB(13,8,2).  This is very close to black, but measures as a slightly lower
density than a max black.  The profile is probably attempting to compensate
for the rather cool black of this printer by adding red-orange.  Is there a
way that I can specify that black should map to RGB(0,0,0)?

The general behaviour of the B2A tables is that any out of gamut colors (after
any gamut mapping) will be mapped to the closest perceptual color. You don't say
which intent (if any) you are dealing with, and without the .ti3 and/or
the profile, it's hard to be more specific. Normally this will be the blackest
possible color, since black is usually a "cusp", and the closest distance from
a point some distance away (like Lab(0,0,)) is the cusp.

Graeme Gill.



Other related posts: