pnmscalefixed

Scale a PNM file quickly with possibly reduced quality. See also: pamscale. More information: https://netpbm.sourceforge.net/doc/pnmscalefixed.html.

pnmscalefixed -width width -height height path/to/input.pnm > path/to/output.pnm

pnmscalefixed -width width path/to/input.pnm > path/to/output.pnm

pnmscalefixed -xscale x_factor -yscale y_factor path/to/input.pnm > path/to/output.pnm