This procedure inverts the supplied colormap applying a fuzzy “not” to each channel component of a pixel (regarding 0 as logical false and 255 as logical true).
The colormap is modified.
The inverted colormap is returned.
> (define image (colormap-readjpg "horses.jpg")) image > (colormap-writejpg (colormap-invert! image) "horses-inverted.jpg") ok >
The input image displays as follows (horses.jpg, JPG, 2400x1600):
The inverted image looks like this: