fotis zagoras schrieb:
Hi,
i have decided to use the CRD-CSA workflow for my printings.
My system is Slackware Linux 9.0 with the newest version
of epsgs 7.07.1.
My printer is a simple HP Deskjet 970Cxi
The tool i'm using to create the printer ICCs is Vuescan.
I'm not sure about the accuracy of this RGB printer
profiles....nevertheless i'm using them as test profiles.
After the conversion of the profile to CRD i.e. printer-crd.ps
and the conversion a general sRGB profile to CSA i.e. sRGB-csa.ps, i have installed both of them in /usr/local/share/ghostscript/7.07/lib
and i'm using them in the following ghostscript filter:
gs -q -dLanguageLevel=2 -dUseCIEColor -sDEVICE=pswrite -sOutputFile=- -dBATCH -dQUIET -dNOPAUSE -dPARANOIDSAFER sRGB-csa.ps printer-crd.ps -
My question is about the correctness of the above statement. With other words ... the correct way to activate the usage of the CRD and CSA in any similar filter. As you see in the filter i'm using now, both of them are included in the print stream. Is this correct ?
Basically yes. The code in sRGB-csa.ps should look like this:
% remap DefaultGray to sRGB
/DefaultGray
[ /CIEBasedA <<
/DecodeLMN [
{ dup 0.03928 le
{12.92321 div}
{0.055 add 1.055 div 2.4 exp}
ifelse
} bind dup dup
]
/MatrixLMN [0.412457 0.212673 0.019334
0.357576 0.715152 0.119192
0.180437 0.072175 0.950301]
/WhitePoint [0.9505 1.0 1.0890]
>> ] /ColorSpace defineresource pop % remap DefaultRGB to sRGB
/DefaultRGB
[ /CIEBasedABC <<
/DecodeLMN [
{ dup 0.03928 le
{12.92321 div}
{0.055 add 1.055 div 2.4 exp}
ifelse
} bind dup dup
]
/MatrixLMN [0.412457 0.212673 0.019334
0.357576 0.715152 0.119192
0.180437 0.072175 0.950301]
/WhitePoint [0.9505 1.0 1.0890]
>> ] /ColorSpace defineresource pop
and printer-crd.ps should look like:
<< ...contents of the CRD... >> setcolorrendering
The commands
<< ...CRD contents... >> /Current exch /ColorRendering defineresource pop
as generated by icc2ps only define the resource, but do not install the CRD into the graphics state. You need to call setcolorrendering to activate the CRD.
I'm just not sure, whether there are some restrictions imposed by ghostscript's "pswrite" device in conjunction with CIE-based color rendering. At least it looks like the "pswrite" device supports only a /DeviceRGB ProcessColorModel, so the CRD should be a RGB one. And my experience is that CIE-based color rendering does not work too well with gs 7.xx anyway (-> banding artifacts, etc.), but works much better with gs 8.xx.
Best Regards, Gerhard
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