pnminvert - invert a PNM image
pnminvert
[pnmfile]
This program is part of Netpbm(1).
pnminvert reads a PNM image as input, inverts it black for white, and produces a PNM image as output.
If the image is grayscale, pnminvert replaces a pixel with one of complementary brightness, i.e. if the original pixel has gamma-adjusted gray value G, the output pixel has gray value maxval - G.
If the image is color, pnminvert inverts each individual RGB component the same as for a grayscale image.
There are no command line options defined specifically
for pnminvert, but it recognizes the options common to all
programs based on libnetpbm (See
Common Options
.)
Copyright (C) 1989 by Jef Poskanzer.