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 {{[-g|-grey]}} {{path/to/input.pnm}} > {{path/to/output.pnm}}

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

pnmhisteq -no{{black|white}} {{path/to/input.pnm}} > {{path/to/output.pnm}}