Lab curves for GIMP

LabCurves is a small program, which allows to use se curves on the L*a*b* color channels of the given image. The internal computation is done with 16 bit, while input and output are 8 bit. Together with a small wrapper script it can be seemlessly used from GIMP.

The construct emerged from dlRaw development. Basically it is a drastically cut down dlRaw version, which is meant as a small sandbox. Therefore it can be adopted for new ideas with very little effort while basic things like color management and preview are ready to go. Since it is an application in its own, it can also be used within commandline tool chains, giving a preview for filters which need it.



LabCurves are a part of Photivo, a 16 bit photo processor with much more features. ;-)


Basic building and installation instructions are included in the corresponding files. (Kindly hosted by


  • L*, a* and b* curve.
  • Saturation curve (adaptive or absolute).
  • Seemless GIMP integration.
  • Internal 16 bit processing.
  • Automatic 16 bit output (if the input has 16 bit color depth).
  • Color managed using lcms 2.

Latest version: 20100709

Your help is needed:

Starting with the version 20100709 lcms 2 and Graphicsmagick Q16 is needed. Since there is no such package in most of the linux distributions, you have to build them yourselves and afterwards LabCurves. Static linking would be a way to get binaries for linux distributions again, but I have no clue how to link these two libraries statically, so please explain it to me. I would be happy to share linux binaries again. ;-)


  • Read this.
  • Read the information files included in the packages.
  • Make sure GIMP and python work together. (python in GIMP for windows)
  • Make sure the script and the program are executable.
  • Delete the corresponding file in ~/.config/mm (Linux) \"user data"\mm (Windows).
  • Contact me ;-)

Feedback is very welcome.

greets mike