[cups] some IPP attributes don't work for some printers

Jacob Marble jacobmarble at google.com
Tue Sep 8 16:39:25 PDT 2015


A PPD for a particular color printer lacks a ColorModel entry, but CUPS
indicates that color printing is possible with:

color-supported=true
print-color-mode-default=color
print-color-mode-supported=color,monochrome

So, instead of printing with the ColorModel attribute, I use
print-color-mode=monochrome. But. Color comes out of the printer.

Digging into other PPD entries, I found this attribute, which *does*
control color vs monochrome in print tests:
*OpenUI *CMAndResolution/Print Color as Gray: PickOne

Looks like this occurs in a dozen or so HP printers, out of my collection
of about 7000 PPDs from multiple manufacturers.

How does CUPS decide that this printer should have the print-color-mode
attribute? Is this a bug in CUPS or in the PPD?

Jacob



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