[Printing-architecture] Make use of extended color spaces on IPP printers

Till Kamppeter till.kamppeter at gmail.com
Sun May 9 21:31:49 UTC 2021

On 09/05/2021 22:55, Michael Sweet wrote:
> Till,
>> On May 9, 2021, at 4:14 PM, Till Kamppeter <till.kamppeter at gmail.com> wrote:
>> ...
>> But this would be the task of the renderer then. Does Ghostscript do this?
> It might, but certainly not with the current CUPS driver.

Probably I have to check with the Ghostscript developers to see what to 
add to the ghostscript() filter function to make the Ghostscript called 
by it do this.

>> 1. Let us in the second use case assume that the t-Online logo is complete represented as vector graphics, like an SVG, but not necessarily in any standard format. How is its color defined then? An how the color space?
> So there you would need to look at the PDF content stream or the page's dictionary (and its Resources array).  Any resource object that has an array value with "/ICCBased" is an ICC color space, and the referenced object after the "/ICCBased" is the ICC profile.  There are other ways that common profiles can be specified/approximated (e.g. "CalRGB" is approximately sRGB and "CalGray" is approximately sGray).

Zre their more "variants" of sRGB and AdobeRGB? Is this documented 
somewhere? I hope this does not get arbitrarily complicated to rasterize 
a vector PDF into the desired color space.

>> 2. And how about a PDF with a mix of sRGB and AdobeRGB images? Should we produce the resulting (raster) page
>>   in AdobeRGB then as this has the wider gammut?
> In general, yes.  If there is also device RGB support and you have a profile, then *that* is your best color space.

OK, then I will go this way.


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