Icon-Compositor 0.0
Invert

invert(image)

The invert function is used to create a new image by inverting the color channels of an image, to form a negative image. Its bounding box will be the same. The alpha channel is unchanged.

icomp 'invert( dragon.png )' -o invert-dragon.png
   
The single quotes are only needed on the command line (to insulate the parentheses from the shell) they must not appear in an icomp(1) script.