pnmhisteq

Histogram-equalize a PNM image. More information: https://netpbm.sourceforge.net/doc/pnmhisteq.html.

• Increase the contrast of a PNM image using histogram equalization:

pnmhisteq path/to/input.pnm > path/to/output.pnm

• Only modify grey pixels:

pnmhisteq -grey path/to/input.pnm > path/to/output.pnm

• Do not include black or white pixels in the histogram equalization:

pnmhisteq -noblack|white path/to/input.pnm > path/to/output.pnm