pnmhistmap

Draw a histogram of a PNM image. More information: https://netpbm.sourceforge.net/doc/pnmhistmap.html.

• Draw a histogram of a PNM image:

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

• Draw the histogram as dots instead of bars:

pnmhistmap -dots path/to/input.pnm > path/to/output.pnm

• Specify the range of intensity values to include:

pnmhistmap -lval minval -rval maxval path/to/input.pnm > path/to/output.pnm