ppmnorm

Normalize PPM image contrast range

TLDR

Normalize image contrast

$ ppmnorm [input.ppm] > [output.ppm]

Specify percentile range

$ ppmnorm -bpercent [2] -wpercent [1] [input.ppm] > [output.ppm]

ppmnorm normalizes the contrast of a PPM image by stretching its color histogram to use the full available range. Dark images are brightened and washed-out images gain contrast, making it a quick automatic enhancement tool.The black and white percentile parameters control how aggressively the ends of the histogram are clipped before stretching, preventing outlier pixels from limiting the enhancement. This is an alias for pnmnorm operating in color mode. Part of the Netpbm toolkit.

PARAMETERS

FILE

Input PPM file.

-bpercent N

Black percentage.

-wpercent N

White percentage.

-bvalue N

Black cutoff value.

-wvalue N

White cutoff value.

INSTALL

sudo apt install netpbm

sudo dnf install netpbm

sudo pacman -S netpbm

sudo apk add netpbm

sudo zypper install netpbm

brew install netpbm

nix profile install nixpkgs#netpbm

CAVEATS

Alias for pnmnorm with color. Part of Netpbm suite.

HISTORY

ppmnorm was created as part of Netpbm for color image normalization.