You select Color, it prints Grayscale

[Teo]

- Open a document in qpdfview
- Go to File/Print
- Click on the "Options" button
- Select the "Options" tab
- Under "Color Mode" make sure "Color" is selected (as opposed to "Grayscale"), which it is by default
- Print

Expected: should print in color (if the printer is capable of that, of course)

Observed: it may print in Grayscale if that's the printer's current/default setting.

In fact, if you click on the "Properties" button next to the selected printer, a window pops up with printer properties, and there is an "Advaced" tab. In that tab, there are several printer settings whose value are listed but you CANNOT CHANGE. I guess the exact set of settings may depend on the printer. In my case there's a "Print Quality" setting whose default value is "Draft Grayscale". In ALL other software, when opening the printer settings, I would be allowed to change this setting and select for example "Normal Color" or "Draft Color". Here I cannot change the current setting which is Draft Grayscale despite having selected Color in qpdfview's own settings.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: qpdfview 0.4.7-1
ProcVersionSignature: Ubuntu 3.13.0-29.53-generic 3.13.11.2
Uname: Linux 3.13.0-29-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
CurrentDesktop: Unity
Date: Wed Jun 18 20:26:11 2014
InstallationDate: Installed on 2013-10-11 (250 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
SourcePackage: qpdfview
UpgradeStatus: Upgraded to trusty on 2014-05-24 (25 days ago)

[Benjamin Eltzner (b-eltzner)]

Hi Teo, thank you for the feedback. You reported the bug against the qpdfview package instead of the project, which is also hosted on Launchpad. I therefore add your bug reports to the porject's bug tracker.

[Adam Reichold (adamreichold)]

Hello Teo,

this is a tough one: We use Qt's default printing dialog and so we have no influence ourselves on which printer properties you can change and which you cannot. But we will copy those settings into our printing request so they will be passed to the printer driver. And we can't override them since they are printer-specific and we don't know their names.

Another problem is that the "Color" option themselves does not do anything (as opposed to "Gray" which will request "ColorModel=Gray" from CUPS), since we don't known if "Color" is supposed to mean "CMYK" or "RGB" as this depends on the printer driver as well. (So we just keep the default and change nothing if "Color" is selected.)

Newer version of Qt5 (specifically Qt 5.2) have a very much improved properties dialog which should let you change those values. Sadly, I currently don't see anything we can do other than suggesting to change the default value of "Print Quality" which of course is not really a solution.

(I will try to research how Qt interprets the "Color" setting internally, maybe this will lead to a solution, but I am not sure yet...)

Best regards, Adam.

[Adam Reichold (adamreichold)]

Hello again,

I search the Qt code base and apparently the "ColorMode" is respected when printing to PDF or under Windows but ignored for printing with CUPS. (Maybe because of the problem that it is unclear whether to set it to CMYK or RGB. I'll have to do more research on that.)

Regards, Adam.

[Adam Reichold (adamreichold)]

Ok, since bug report #1331662 seems resolved, we are still left with the question on how to force color mode, i.e. deciding whether to request CMYK or RGB as the input color model for the driver.

[Adam Reichold (adamreichold)]

Just to understand this correctly, in other applications, is it possible color output while having the "Print Quality" at "Draft Grayscale"? I.e. does "Print Quality" override the color mode setting? (Because the only thing that I can generically request from CUPS is the color mode of the content it sends to the printer driver, not that of the output.)

[Teo (teo1978)]

In all the other applications I've ever seen in Linux (until I tried other Qt-based apps driven by your suggestion), there is no independant "color mode" setting at all. The only way to choose whether to print in color or grayscale is, in a way or another, to choose one of the Print Quality settings. At least with this printer.

[Adam Reichold (adamreichold)]

Hello again,

could you try the dailydebs when at least trunk revision 1585 is built? (Or build directly from the trunk source if you're comfortable with that.)
It should try to determine whether the printer supports the color model CMYK or if not then at least
RGB and request that to be used. Is this sufficient to yield colored output if "Color" is selected in Qt's print dialog?

Best regards, Adam.

[Adam Reichold (adamreichold)]

Marking this incomplete since we are still missing feedback on the possible solution.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.