pgmtoppm
Colorize a PGM image.
TLDR
Map all greyscale values of the input image to all colors between the two specified colors
$ pgmtoppm -black [red] --white [blue] [path/to/input.pgm] > [path/to/output.ppm]
Map all greyscale values of the input image to colors according to the specified colormap
$ pgmtoppm -map [path/to/colormap.ppm] [path/to/input.pgm] > [path/to/output.ppm]
