(colormap-scale colormap x-factor y-factor)
This procedure scales a colormap by a factor in X and Y direction. The minimum resulting colormap dimensions are 1x1 (one RGB pixel). The parameters need to be inexact factors.
The resulting colormap is returned.
> (define grabber (grabber-create "/dev/video2" 2000 2000))
grabber
> (define cm (grabber-grab grabber))
cm
> cm
#<colormap orow:-1 ocol:-1 xres:-1 yres:-1 h:1080 w:1920>
> (colormap-scale cm 0.5 0.5)
#<colormap orow:-1 ocol:-1 xres:-1 yres:-1 h:540 w:960>
>