Color calibrating scanner with GNOME

Color calibrating scanner with GNOME

[Jack Hill]

Hi Guix,

I'm trying to color calibrate my scanner while running GNOME by following 
these instructions: 
https://help.gnome.org/users/gnome-help/stable/color-calibrate-scanner.html.en

I have produced a tiff of my calibration target, but my scanner doesn't 
show up in the GNOME settings color submenu. The only device show is my 
laptop screen.

GNOME's simple-scan and sane-backend's* scanimage can use the scanner, and 
scanimage reports it as:

$ scanimage -L
device `pixma:MF4800_Canon5e5c59' is a CANON Canon i-SENSYS MF4800 Series multi-function peripheral

The device is connected over the network.

What should I do to try to calibrate my scanner?

Best,
Jack

* The name of this package is slightly confusing, since it also contains 
the front-end tools like scanimage. I don't know if it makes sense to make 
a change here or not.

Re: Color calibrating scanner with GNOME

[Jack Hill]

On Sat, 16 Mar 2019, Jack Hill wrote:

> Hi Guix,
>
> I'm trying to color calibrate my scanner while running GNOME by following 
> these instructions: 
> https://help.gnome.org/users/gnome-help/stable/color-calibrate-scanner.html.en
>
> I have produced a tiff of my calibration target, but my scanner doesn't show 
> up in the GNOME settings color submenu. The only device show is my laptop 
> screen.
>
> GNOME's simple-scan and sane-backend's* scanimage can use the scanner, and 
> scanimage reports it as:
>
> $ scanimage -L
> device `pixma:MF4800_Canon5e5c59' is a CANON Canon i-SENSYS MF4800 Series 
> multi-function peripheral
>
> The device is connected over the network.
>
> What should I do to try to calibrate my scanner?

I've done some more troubleshooting:

I installed GNOME 3.30 (newer GNOME than current Guix master) on a Debian 
10 (buster, testing) host. The scanner did not show up in the calibration 
dialog when connecting over the network. I suspect that this is because 
GNOME hardware/calibration does not trigger the search of the network for 
scanners. When I plugged it in via USB, it did show up in the calibration 
dialog. (Unfortunately, it doesn't scan over USB because of some as yet 
undetermined bug in sane or the device firmware (I'm extra suspicious of 
it because it is a multi-function device, so I imagine is more complex.).)

On Guix, when the scanner is connected via USB it cannot be found by my 
user's scanning programs (or, therefore, the GNOME hardware/calibration 
dialog). However, it can be found as root. I suspect the problem is a 
missing udev rule. What is the right way to proceed?

Best,
Jack

Re: Color calibrating scanner with GNOME

[Jack Hill]

On Sat, 16 Mar 2019, Jack Hill wrote:

> On Guix, when the scanner is connected via USB it cannot be found by my 
> user's scanning programs (or, therefore, the GNOME hardware/calibration 
> dialog). However, it can be found as root. I suspect the problem is a missing 
> udev rule. What is the right way to proceed?

Indeed, it was a udev problem. Adding:

(simple-service 'sane-udev-rules udev-service-type (list sane-backends))

to my services solves the problem and I can see the scanner from my 
unprivileged user, and it shows up the the GNOME hardware/calibration 
dialog. Unfortunately, clicking on the "calibrate" button does nothing. On 
Debian buster with GNOME 3.30, doing so brings up a calibration wizard.

I also noticed since adding this rule that, I get messages like:

udevd[3658]: specified group 'scanner' unknown

in dmesg. Should adding the sane udev rules also create a scanner POSIX 
group? Thoughts? I'll have to check out how Debian handles this.

Best,
Jack

Re: Color calibrating scanner with GNOME

[Jack Hill]

On Sat, 16 Mar 2019, Jack Hill wrote:

> I can see the scanner from my unprivileged user, and it shows up the the 
> GNOME hardware/calibration dialog. Unfortunately, clicking on the 
> "calibrate" button does nothing. On Debian buster with GNOME 3.30, doing 
> so brings up a calibration wizard.

I believe that I have determined why this is so. There is needed software 
which is not yet packaged for Guix. The calibration wizard is provided by 
gnome-color-manager [0]. Gnome-color-manager depends on argyllcms [1], 
which is also not yet packaged. Argyllcms in turn requires the Jam build 
tool [2][3] or the Jam fork by FreeType, ftjam [4]. Jam is also not yet 
packaged. As a little twist for Jam, it looks like Perforce upstream 
stopped developing it in 2014, and the FreeType fork's latest release 
seems even older. It is still available in modern Debian, so hopefully 
this won't be too much of hurdle.

[0] https://gitlab.gnome.org/GNOME/gnome-color-manager
[1] https://www.argyllcms.com/
[2] https://www.perforce.com/documentation/jam-documentation
[3] https://swarm.workshop.perforce.com/projects/perforce_software-jam/files/main
[4] https://www.freetype.org/jam/index.html

Best,
Jack