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

[Jacob Marble]

Thanks

Jacob

On Wed, Sep 9, 2015 at 12:44 PM, Michael Sweet <msweet at apple.com> wrote:

> Jacob,
>
> > On Sep 8, 2015, at 7:39 PM, Jacob Marble <jacobmarble at google.com> wrote:
> >
> > 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?
>
> The PPD.
>
> CUPS looks for the ColorDevice keyword in the PPD, and uses that to
> determine what values of the print-color-mode attribute  are supported.
> CUPS supports the standard ColorModel plus a handful of non-standard
> keywords that directly map to it for applying the print-color-mode value,
> but *not* CMAndResolution (which by its name is likely a non-standard
> combination of ColorModel and Resolution...)
>
> _________________________________________________________
> Michael Sweet, Senior Printing System Engineer, PWG Chair
>
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