[argyllcms] Re: HP B110a - RGB or CMYK ?
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 29 Mar 2011 08:39:26 +1100
János, Tóth F. wrote:
Is there an objective way to determine if a printer driver expects RGB or
CMYK input?
Hi,
Yes, examine one of its existing ICC profiles. But note that it's
possible that some devices have more than one way of being driven.
(ie. a RIP typically accepts documents in RGB, but internally
it will convert from RGB to CMYK or the devices native format.
You will generally get a better result by profiling and driving it
in a format that's closer to being native.)
The setup installed an RGB based "shaper+matrix" (basically a standard
AdobeRGB space, but with strange parametric curves) by default, so I
profiled it as an RGB printer.
But there are two concerns:
1: The printed colors are not really match with the colors which I can see
on my display. (But I used only 420 patches for an XYZ cLUT, I didn't try
Lab cLUT profiles with more patches yet.)
Printed colors rarely match displays because:
1) The gamut of the devices is different
2) The viewing conditions are different
3) The white points may be different
4) Both the printer and the display need to have been profiled,
and the input color being displayed on both needs to have been
interpreted as being in the same source color space, and processed
in a similar way (ie. intent etc.)
2: Adobe PDF Pro X chooses a CMYK profile by default when I try to print any
PDF documents.
If I select my RGB profile then it says "Composite RGB" as an output color
format on the CMS tab but I still have the "CMYK Ink Manager" on the main
Output tab.
It seems like PDF Pro thinks I have a CMYK printer (as much as I know it
should detect it automatically ; but of course it can be buggy...) and only
accepts the RGB profile because it was a manual override (and I have
slightly wrong colors because there is a CMYK->RGB->CMYK conversion when I
print with this profile...)
Sorry, I don't know anything specific about this application. Perhaps someone
else on this list may be able to help, or you could pose the question
on one of the Adobe forums, or the Colorsync list.
Graeme Gill.
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