pnminvert

Invert image colors

$ pnminvert [input.pnm] > [output.pnm]

$ cat [image.pnm] | pnminvert > [output.pnm]

pnminvert [file]

pnminvert produces a photographic negative of a PNM image by inverting all pixel values. Each sample value is replaced with the maximum value minus the original value, effectively swapping light and dark.
The tool works with all PNM types: PBM (black/white bits are flipped), PGM (grayscale values are inverted), and PPM (each color channel is independently inverted). Part of the Netpbm toolkit; superseded by paminvert.

FILE

Input PNM file.

Simple color inversion. Part of Netpbm suite.

pnminvert was created as part of Netpbm for image inversion operations.

paminvert(1), ppmchange(1), pnmarith(1)