Desde
esta entrada en el foro de photivo me encuentro con
delaboratory. La cosa promete:
delaboratory is a Free Software color correction utility, it allows you to modify color/contrast of your photo in a creative way - using curves, mixer, blending, blur and ND filters in different colorspaces (RGB/BW, XYZ/LAB, CMY/CMYK, HSL/HSV) with floating-point precision per channel, each operation is stored as an adjustment layer and you can watch a realtime preview.
Eso si, es alpha requetealpha. A ver si no muere