[Gimp-developer] Bug reports that would be nice to see on the milestone 2.10 list

[Elle Stone <ellestone ninedegreesbelow com>]

There are some bug reports listed below that pertain to color management 
and color mixing, that I would very much like to see be put on the 
"milestone 2.10" list. Here's why:

I just posted a tutorial on using GIMP to make an illustration from a 
photograph: 
http://ninedegreesbelow.com/photography/leaves-in-may-illustration-from-photograph.html

If you look at the articles on my website 
(http://ninedegreesbelow.com/photography/articles.html), there are a 
bunch of articles on using high bit depth GIMP, because high bit depth 
GIMP is my favorite image editor ever, hands down more useful than 
PhotoShop ever was (though I dearly miss having adjustment layers).

Personally I don't use default GIMP 2.9 for editing, but rather a 
patched version of GIMP 
(http://ninedegreesbelow.com/photography/patched-gimp-compared-to-default-gimp.html).

When I write a tutorial on using GIMP, I try to include information on 
using default GIMP as well as my patched version of GIMP. But I keep 
running into the same problems with trying to edit using default GIMP:

* No LCH color pickers and no LCH Hue-Chroma tool 
(https://bugzilla.gnome.org/show_bug.cgi?id=749902)

* No Luminance blend mode 
(https://bugzilla.gnome.org/show_bug.cgi?id=753163).

* No easy way to make Curves and Levels adjustments on linear RGB 
(https://bugzilla.gnome.org/show_bug.cgi?id=757444)

* No obvious way to invert colors on linear RGB 
(https://bugzilla.gnome.org/show_bug.cgi?id=757686).

* No easy way to draw a gradient using linear RGB 
(https://bugzilla.gnome.org/show_bug.cgi?id=735897).

* No easy way to correctly decompose to LAB/LCH and then be able to drag 
layers back to the layer stack 
(https://bugzilla.gnome.org/show_bug.cgi?id=765178 - also affects my 
patched GIMP, except I disabled decompose altogether for unrelated reasons).

* No easy way to correctly extract LAB/LCH channels as layers 
(https://bugzilla.gnome.org/show_bug.cgi?id=755376 - also affects my 
patched GIMP).

If the above issues were fixed, then default GIMP would be very useable 
for following the steps in my tutorials as long as the user sticks with 
the built-in sRGB color space. And I could go through my tutorials and 
remove passages like "here's the workaround for default GIMP", "here's 
how to get the right LAB/LCH layers", "the workaround for default GIMP 
is too complicated to explain in this tutorial", and so forth.

And then I think the only remaining major advantage my patched GIMP 
would have over default GIMP would be the ability to edit in user-chosen 
RGB working spaces. Well, that and I've unclamped a few additional blend 
modes and etc, to make some VFX people happy (and this unclamping turns 
out to be useful for general editing).

Going beyond the fact that I'd really like to rewrite my GIMP tutorials 
to sound less critical of default GIMP, the above-listed bug reports 
fall into three fairly important categories:

1. Allow GIMP users to take full advantage of LCH blend modes, which is 
something I don't think any other image editors yet provide.

2. Allow GIMP users to produce radiometrically correct results for 
editing operations that affect tonality. Right now GIMP users get gamma 
artifacts every time they use Levels or Curves or invert colors, and 
they have to resort to workarounds to draw a linear gamma gradient. For 
an image editor that purports to make radiometrically correct editing 
results easy to produce, this is an unfortunate situation.

3. Fix GIMP's handling of LAB/LCH decompose and GEGL's extract 
component, so that GIMP users will be able to use LAB/LCH layers and 
actually get correct results from drag and drop and such.

I realize that developer time is limited, and of course I'm willing to 
help update and test patches for the above bug reports.

I also realize that everyone thinks their own bugs are "the most 
important", and perhaps I'm overestimating the importance of the above 
bugs (but I don't think I am). But like I said, I keep running into the 
same issues every time I try to use default GIMP, so I thought I'd at 
least make a post on the subject.

Best,
Elle
--
http://ninedegreesbelow.com
Color management and free/libre photography