Palettes saved as .gpl lack "Name" field

Phanterm · November 4, 2024, 1:40am

When saving palette files as .gpl (GIMP palette format), I noticed that these files were not being imported properly into Krita. Upon investigation, this turned out to be because the .gpl file had no “Name” field, which I guess Krita needs in order to properly display the palette in its Resource viewer.

A) .gpl as saved by Aseprite:

GIMP Palette
Channels: RGBA
#
  0   0   0   0	Untitled
[cont...]

Result

Fails to appear in Krita.

B) .gpl after adding Name field

GIMP Palette
Name: My Cool Palette
Channels: RGBA
#
  0   0   0   0	Untitled
[cont...]

Result

Imports successfully into Krita.

I’ve filed a similar report over on Krita’s forum, as I don’t know the inner workings of this format to know where the problem lies. But it would be nice if the .gpl files could export with this field attached.

P.S. I’m not sure how to test these since Krita has default .gpl files I can compare to, but .ase and .pal palette files also don’t import correctly in Krita. Again, not sure where the problem lies here.

behreandtjeremy · November 4, 2024, 3:24am

I was able to reproduce.

There may be other complications due to standard gpl and jasc pal files handling only RGB24, not RGBA32. After a name is added to the top of the gpl file, Krita interprets each swatch’s alpha channel as part of swatch name. The “Channels: RGBA” line is specific to Aseprite.

I’m guessing the alpha channel would be why jasc pal files don’t load in Krita.

Aseprite is supposed to only add the alpha channel on export if your palette has colors that require it, though.

Adobe Swatch Exchange palette files use the extension ase, the same as Aseprite files, but the two are not the same.

Krita’s import gpl routine:

github.com

KDE/krita/blob/5cecb06cac0bc5ed2d3bcb7f3b1104e567e2c6ed/libs/pigment/resources/KoColorSet.cpp#L1329


      
                      if (entry.name().isEmpty())
                          stream << "Untitled\n";
                      else
                          stream << entry.name() << "\n";
                  }
              }
          
              return true;
          }
          
          bool KoColorSet::Private::loadGpl()
          {
              if (data.isEmpty() || data.isNull() || data.length() < 50) {
                  warnPigment << "Illegal Gimp palette file: " << colorSet->filename();
                  return false;
              }
          
              quint32 index = 0;
          
              QStringList lines = readAllLinesSafe(&data);

Aseprite’s export gpl routine:

github.com

aseprite/aseprite/blob/c83dd16a43fd52ead709f0c9e78e7d7acb54dac1/src/doc/file/gpl_file.cpp#L104


      
          
            base::trim_string(comment, comment);
            if (!comment.empty()) {
              LOG(VERBOSE, "PAL: %s comment: %s\n", filename, comment.c_str());
              pal->setComment(comment);
            }
          
            return pal;
          }
          
          bool save_gpl_file(const Palette* pal, const char* filename)
          {
            std::ofstream f(FSTREAM_PATH(filename));
            if (f.bad()) return false;
          
            const bool hasAlpha = pal->hasAlpha();
          
            f << "GIMP Palette\n";
            if (hasAlpha)
              f << "Channels: RGBA\n";
            f << "#\n";

In the mean time, what I do is export gpl and ase palette files from Aseprite using a Lua script.