GMIC QT doesn't do negative parameters in Gimp-devel

Jan_Moren · January 20, 2018, 12:05pm

G’MIC QT in the 2.9 developer release of Gimp for Linux 64 bits doesn’t accept negative parameter values with the sliders.

Go to, say “color grading”, then try to pull the cool / warm parameter slider to a negative (cool) value. You will get a warmer image whichever way you adjust the value. Same thing with S-curve contrast and other parameters. If you enter a negative value directly it will briefly be accepted, but soon (I assume once the slider controller updates itself) it reverts to the absolute value again.

afre · January 20, 2018, 12:38pm

It works for me. Where did you get GIMP? I am using @partha’s Windows binary. Maybe try the Weekly GIMP 2.9.x AppImage builds.

David_Tschumperle · January 20, 2018, 1:33pm

Just tested with G’MIC 2.1.9 on GIMP 2.9, and it works for me too.
I admit I don’t have any explanations.

Claes · January 20, 2018, 1:39pm

@Jan_Moren is correct.
I got the same behaviour here, using
G’MIC-Qt for GIMP 2.9 Linux 64 bits - 2.1.5
and The Gimp 2.9.9 dev in a 64-b Ubuntu Studio 17.10.

Have fun!
Claes in Lund, Sweden

Jan_Moren · January 20, 2018, 1:41pm

I got Gimp and G’MIC from the gimp-egde Launchpad repo by Otto Kesselgulasch. It is, I believe, the default way to install development versions of Gimp on Ubuntu.

Claes · January 20, 2018, 1:45pm

Salut @David_Tschumperle,
Since I can replicate the error that Jan found,
just tell me if you want me to perform any special tests.

Cordialement,
Claes en Lund, La Suède

David_Tschumperle · January 20, 2018, 2:11pm

I’d be interested by reproducing the issue.

Does that happen with latest G’MIC version 2.1.9 released today ?
Does that happen for other filters than color grading ?

Jan_Moren · January 20, 2018, 2:17pm

“Channel processing” works as intended, as does “color temperature”, “HSL Adjustment” and others. Without going through every filter this is the only one I can find.

As for version, this is 2.1.5 and due to reasons (no fixed internet, currently, so I tether to my smartphone), I can’t really upgrade to test.

David_Tschumperle · January 20, 2018, 2:20pm

OK, thanks for the feedback.
This would mean maybe a problem with the filter itself, not with the way controls are implemented.
This is a but reassuring

Jan_Moren · January 20, 2018, 2:44pm

As a note, when the filter (I use this one all the time as a catch-all photo editing filter) ran with the GTK branch it didn’t have this issue. It’s been there ever since G’MIC switched to QT, though.