On Wed 01 Jul 2015 at 12:22:22 +0100, Brian Potkin wrote: > > I'll join the list tomorrow and refer to the Debian bug in my post. > > Done. > > http://sourceforge.net/p/gimp-print/mailman/gimp-print-devel/thread/20150701101803.GB20876%40copernicus.demon.co.uk/#msg34257165
Meanwhile, I came across http://sourceforge.net/p/gimp-print/bugs/632/ http://sourceforge.net/p/gimp-print/bugs/652/ http://sourceforge.net/p/gimp-print/mailman/gimp-print-devel/thread/467C7753.1010801%40tabi.org/#msg15590162 The third link has some quite detailed explanations. It is from eight years ago; how accurate it is regarding CUPS' treatment of colour today I do not know. Some selected quotes in answer to suggestions and requests to the Gutenprint maintainers that CMYK be the default Color Model: Hi, thanks for the replort. However, I believe you are mistaken about the requirement: as I understand it, the input color model should be RGB by default. The output color model to the printer is whatever the printer requires for the particular printmode, and is set by the driver (for some simple modes it will be CMYK). If you have a special requirement where the input to the printer driver is CMYK, then you should set the input mode to that (and you can make it the default) but for the vast majority of printing inputs, the model to be used is RGB. Gernot Hassenpflug Regarding the color model, RGB is correct. The driver accepts RGB input, as is standard also on Windows. The application therefore sends RGB data to the driver. This has nothing to do with what ink data the driver sends to the printer---that differs for each mode in any case, and is mostly not settable by the user (a mode usually has a fixed requirement for a particular inkset, they are not independently settable). Gernot Hassenpflug The output will always be in the printer's space, whatever the input may be. It's usually better for Gutenprint to do the RGB->CMYK conversion than CUPS, because Gutenprint has more information. Robert Krawitz The choice of color model selects what's passed to Gutenprint, so for any given document, it simply changes what color processing is done in CUPS vs. what is done in Gutenprint. So when you select CMYK, CUPS...... Robert Krawitz If your document is RGB, and you select RGB as the Color Model, CUPS won't do any conversion. Likewise if you print a CMYK document using CMYK color model. If you print an RGB document but select CMYK as the Color Model, CUPS *has* to do a color conversion. Robert Krawitz Apart from the printer model, #497936 is the same bug. Regards, Brian. -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: https://lists.debian.org/[email protected]
