[argyllcms] Re: ArgyllCMS V1.1.0 RC1 is now available

  • From: "Alastair M. Robinson" <profiling@xxxxxxxxxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sat, 07 Nov 2009 01:15:09 +0000

Hi :)

Graeme Gill wrote:

Hmm. As far as I can tell the auto aim values are for 100% colorant
for your file (ie. if you do a plot with -p, all the crosses are at 1.0),
since your device response is already pretty linear, and doesn't fall
over very much near 100%.

Ah, I've misread / misunderstood the meanings of the fields in the .cal file, then - I was thinking the DELMAX_AIM values were the suggested ink limit. Oddly enough for CMY and K they're fairly close to the per-channel ink limits GPLin suggests - the coincidence was confusing me!

The device response of that .ti3 file looks roughly linear largely because there's a significant gamma adjustment being applied between the targen-created testchart and the printer - (a) to avoid using absurd amounts of ink, and (b) to better distribute the test patches.

(Any chance of a future version of targen being able to generate gamma-adjusted step wedges, by the way?)

[If you look at the .cal then DEVMAX_USED is 1.0 for all the inks.]

Yup, I see that. So I take it the auto-aim doesn't attempt to use the hue-shifts at colorant saturation to decide where to stop?

I tried applying the gamma adjustment to the device input values in the .ti3 file, and the five colorants still get a DEVMAX_USED of 100%, and black gets about 50% - I shall experiment further :)

All the best,
Alastair M. Robinson

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