ppmbrighten
Adjust PPM image brightness and saturation
TLDR
Increase brightness
$ ppmbrighten -v [50] [input.ppm] > [output.ppm]
Decrease saturation$ ppmbrighten -s [-30] [input.ppm] > [output.ppm]
Adjust both$ ppmbrighten -v [20] -s [10] [input.ppm] > [output.ppm]
Normalize first$ ppmbrighten -n -v [30] [input.ppm] > [output.ppm]
SYNOPSIS
ppmbrighten [options] [ppmfile]
DESCRIPTION
ppmbrighten adjusts the brightness and saturation of a PPM image. It works in HSV color space, changing value (V) and saturation (S) components.
Part of Netpbm toolkit.
PARAMETERS
-v value
Value (brightness) change (-100 to 100).-s saturation
Saturation change (-100 to 100).-n
Normalize value range first.
EXAMPLES
$ # Brighten image
ppmbrighten -v 30 photo.ppm > bright.ppm
# Desaturate (toward grayscale)
ppmbrighten -s -50 photo.ppm > muted.ppm
# Increase vibrancy
ppmbrighten -s 40 photo.ppm > vivid.ppm
# Normalize and brighten
ppmbrighten -n -v 20 dark.ppm > fixed.ppm
# Chain operations
jpegtopnm photo.jpg | ppmbrighten -v 20 | pnmtojpeg > bright.jpg
ppmbrighten -v 30 photo.ppm > bright.ppm
# Desaturate (toward grayscale)
ppmbrighten -s -50 photo.ppm > muted.ppm
# Increase vibrancy
ppmbrighten -s 40 photo.ppm > vivid.ppm
# Normalize and brighten
ppmbrighten -n -v 20 dark.ppm > fixed.ppm
# Chain operations
jpegtopnm photo.jpg | ppmbrighten -v 20 | pnmtojpeg > bright.jpg
CAVEATS
Values outside -100 to 100 are clamped. Works on PPM only. Consider pamaltsat for more options.
HISTORY
ppmbrighten is part of Netpbm by Jef Poskanzer and contributors for basic color adjustment.
SEE ALSO
ppmcolormask(1), ppmgamma(1), pamaltsat(1), netpbm(1)