ppmrainbow

Generate a rainbow. More information: https://netpbm.sourceforge.net/doc/ppmrainbow.html.

• Generate a rainbow consisting of the specified colors:

ppmrainbow color1 color2 ... > path/to/output_file.ppm

• Specify the size of the output in pixels:

ppmrainbow -width width -height height color1 color2 ... > path/to/output_file.ppm

• End the rainbow with the last color specified, do not repeat the first color:

ppmrainbow -norepeat color1 color2 ... > path/to/output_file.ppm