🚀 go-pugleaf

Lou,

thanks for your examples. They explain nicely the black
generation.
I don't have ColorThink, but one can get some insight as
well by ProfileMaker > ProfileEditor > GrayBalance.

Inspecting some older inkjet profiles, I found that the
results are depending very much on the chosen GCR method
and parameters. Sometimes Y is monotonously increasing,
sometimes not.
Now, all this concerns profile CLUTs BtoA1 (1 for Relcol)
together with the associated onedimensional input and
output curves. Input is Lab, output CMYK. Ink limit is
here established.

The CLUTs AtoB1 (together with IO-curves, which are mostly
straight lines) reflect the results of target printing
and measuring. Input is CMYK, output is Lab.
Instead of printing 65536 patches, about 1000...1500 are
used, and the other table entries are interpolated.
Here we don't have a total ink limit (TIL). Both targets
ECI-2002CMYKi1 and IT8.7-3CMYKi1 contain patches with CMYK
100% each, 400% ink.

Nevertheless, at least an inkjet print has to be protected
against too much ink.
My workflow, using a RIP, is as follows:
1. Print linearization target by RIP.
2. Let dry one day.
3. Make linearization profile by RIP.
4. Prink ink limit target, inspect visually and define TIL.
   So far we have a linearized machine with explicitly
   defined 'RIP-TIL'.
5. Print calibration target by Photoshop.
   Excesssive ink is prevented by RIP-TIL.
6. Let dry one hour.
7. Make Profile by ProfileMaker, using a Profile-TIL, which
   should not be larger than the RIP-TIL.
As a result, we have TIL in fact at two positions: in the RIP
and in the profile.

My toner printers (PostScript) don't have linearization, there
is no external RIP and no RIP-TIL. The machines are perhaps
internally protected internally against too much toner.

Best regards --Gernot Hoffmann