pnmnorm
Normalize the contrast in a PNM image.
See also: pnmhisteq
.
More information: https://netpbm.sourceforge.net/doc/pnmnorm.html.
- Force the brightest pixels to be white, the darkest pixels to be black and spread out the ones in between linearly:
pnmnorm
path/to/image.pnm >
path/to/output.pnm
- Force the brightest pixels to be white, the darkest pixels to be black and spread out the ones in between quadratically such that pixels with a brightness of
n
become 50 % bright:
pnmnorm -midvalue
n
path/to/image.pnm >
path/to/output.pnm
- Keep the pixels' hue, only modify the brightness:
pnmnorm -keephues
path/to/image.pnm >
path/to/output.pnm
- Specify a method to calculate a pixel's brightness:
pnmnorm -
luminosity|colorvalue|saturation
path/to/image.pnm >
path/to/output.pnm