NAME

       vtgamma - set gamma correction on text terminals

SYNOPSIS

       vtgamma [-e] [-r] [-l] <gamma>
       vtgamma [-e] [-r] <red gamma> <green gamma> <blue gamma>
       vtgamma [-e] [-r]<palette>[<gamma>...]

DESCRIPTION

       vtgamma  allows  you  to  set  the  gamma  correction  on  Linux console.  It also works on most terminal
       emulators as well.  A good deal of monitors tend to have too dark blue -- human eye is far less sensitive
       to blue light.  This is acceptable for photographic images that should look realistically, but can  cause
       blue, especially dark blue, text to be hard to read.

       vtgamma  is  also useful on aged CRT monitors, which tend to rapidly lose the luminance-to-voltage ratio.
       Even after just 2-3 years, typical CRT often needs gamma of as much as 1.6 to resemble a  new  one.   The
       author of this words has seen a specimen that needed gamma of 2 2 6 (ie, with a big loss of blue) despite
       still having sharp display.

       Gamma correction is given as a positive floating-point number, with 1.0 being the default.

       You  may  also select a different palette than default "vga".  A palette may then have a gamma correction
       applied to it -- all options are allowed.

       This version recognizes the following palettes:

              vga
              gruvbox
              monokai
              ubuntu

       To affect the login prompt, it's best to: vtgamma 1.6 >>/etc/issue, where 1.6 is the gamma correction you
       want (but see -p).

       Without -p, the color profile lasts either until the next time a program resets the terminal.  While this
       is quite a rare thing, it happens, and thus you'll probably want to have the gamma refreshed every time a
       program exits.  The recommended way is to include vtgamma in PROMPT_COMMAND:

       PROMPT_COMMAND='vtgamma 1.6'

       although if you don't want to spawn a process every prompt, you may instead edit  ~/.bashrc  and  include
       the output of vtgamma -e 1.6 in PS1, enclosed between \[ and \].  Unfortunately, this won't work when you
       switch between terminals using different ways of setting gamma (currently Linux console vs most graphical
       terminals); Midnight Commander can't cope well with prompts containing such codes either.

OPTIONS

       -e|--escape
              Escapes  the  codes  in  a form suitable for echo -e, C/Perl/... literals, etc.  You might want to
              include this in /etc/issue.

       -p|--permanent
              On Linux console (VT) only, sets the palette in a way that's permanent until reboot.  This uses an
              ioctl rather than terminal codes, thus can't be captured and written as a string.

       -r|--reverse
              Black on white mode.  Note that this does what you'd expect only on  certain  terminals,  such  as
              Linux  console.  On most graphical terminal emulators this affects only "real" black and white but
              not primary text and background colors.

       -l|--lab|--Lab|--lchab|--LCHab
              Uses the LCHab color space (a variant of Lab) instead of RGB, this allows brightening colors above
              FF0000.  Requires the Graphics::ColorObject library (on Debian,  install  libgraphics-colorobject-
              perl).

SEE ALSO

       xgamma(1)

AUTHOR

       Both  the  program  and  this  man  page  are the fault of Adam Borowski.  Both of them are in the Public
       Domain, or the closest approximation allowed by law.

Debian                                             2006-07-10                                         vtgamma(1)