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 {{[-d|-dots]}} {{path/to/input.pnm}} > {{path/to/output.pnm}}

• Specify the range of intensity values to include:

pnmhistmap {{[-l|-lval]}} {{minval}} {{[-rv|-rval]}} {{maxval}} {{path/to/input.pnm}} > {{path/to/output.pnm}}