[argyllcms] Re: Targen options
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sun, 02 Sep 2007 12:06:00 +1000
Ben Goren wrote:
I intend to play around with this this weekend -- assuming I can
get the continuous ink flow system for my printer to actually
work....
I'm trying to figure out if you meant:
xicclu -f if -i r -p x
or
xiiclu -f ib -i r -p x
in order to generate XYZ from RGB -- or possibly something else
entirely for -f.
OK, let's say we have a lut based RGB->PCS profile that we've
created called device.icm. To create the candidate test point
RGB values I'd use:
xicclu -fif -ir device.icm
and feed in suitable Lab values:
90.000000 0.000000 0.000000 [Lab] -> Lut -> 0.912927 0.927358 0.937031 [RGB]
80.000000 0.000000 0.000000 [Lab] -> Lut -> 0.819480 0.853146 0.855490 [RGB]
.
.
20.000000 0.000000 0.000000 [Lab] -> Lut -> 0.287507 0.345025 0.367405 [RGB]
10.000000 0.000000 0.000000 [Lab] -> Lut -> 0.143174 0.177814 0.191570 [RGB]
So the RGB values would form the new grey axis test points.
If I want to add real XYZ expected target values for these points
(to be consistent with the rest of the chart recognition stuff),
then I would feed the RGB value back into the profile in the
forward direction.
xicclu -ff -ia -px device.icm
0.912927 0.927358 0.937031 [RGB] -> Lut -> 0.633962 0.660017 0.585528 [XYZ]
0.819480 0.853146 0.855490 [RGB] -> Lut -> 0.470933 0.490288 0.434955 [XYZ]
Since (by convention) the CGATS XYZ values are scaled to 100, you would
need to multiply the XYZ by 100, e.g. add 63.3962 66.0017 58.5528,
47.0933 49.0288 43.4955 etc. as the expected XYZ in the .ti1 file.
Graeme Gill.
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