(colormap-normalize! colormap)
This procedure applies a simple linear normalization to all 3 color channels of the RGB colormap.
The colormap is modfied.
The modified colormapmap is returned.
> (define e (colormap-difference c d))
e
> (colormap-normalize! e)
#<colormap orow:-1 ocol:-1 xres:-1 yres:-1 w:6720 h:4480>
>