NAME

       pgmramp - generate a grayscale ramp

SYNOPSIS

       pgmramp {-lr|-tb|-rectangle|-ellipse|-diagonal} [-maxval=maxval] width height

       All  options  can be abbreviated to their shortest unique prefix.  You may use two hyphens instead of one
       to designate an option.  You may use either white space or an equals sign between an option name and  its
       value.

DESCRIPTION

       This program is part of Netpbm(1).

       Generates  a  graymap of the specified size containing a black-to-white ramp.  These ramps are useful for
       multiplying with other images, using pamarith.

       The ramp is linear in brightness, not intensity.  I.e. the gamma-corrected sample values in the PGM  rise
       linearly  with  distance  from  the  corner  of  the  image.   If you want a ramp that is linear in light
       intensity, use pnmgamma with pgmramp.

       Options let you choose the shape of the ramp (left to right, inside out, etc.).  You can use  pamflip  to
       get more shapes.  For example, the -lr option gives you a left to right ramp and

           $ pgmramp -lr 100 100 | pamflip -lr

       gives you a right to left ramp.

       To  generate  a  simple ramp of all the values from 0 to maxval, and not necessarily a graphic image, use
       pamseq(1).

       ppmrainbow does something similar to what pgmramp does, but for  color.   The  image  fades  between  two
       colors of your choice.

OPTIONS

       In  addition  to  the options common to all programs based on libnetpbm (most notably -quiet, see  Common
       Options ), pgmramp recognizes the following command line options:

       You must specify exactly one of the ramp type options.

       -lr    A left to right ramp.  Black on the left; white on the right.

       -tb    A top to bottom ramp.  Black on top; white on the bottom.

       -rectangle
              An outside-in rectangular ramp.  It is black around the edges and white in the center.

       -ellipse
              An outside-in elliptical ramp.  It is black around the edge and white in the center.

       -diagonal
              A ramp from top left corner diagonally down to bottom right.  Black at the top left; white at  the
              bottom right.

              This option was new in Netpbm 10.66 (March 2014).

       -maxval=maxval
                   The maxval for the generated image.  Default is 255.

                   This option was new in Netpbm 10.1 (June 2002).  Before that, the maxval
                   is always 255.

SEE ALSO

       pamflip(1), pamarith(1), pnmgamma(1), pamseq(1), ppmrainbow(1), pamgradient(1), pgm(1)

AUTHOR

       Copyright (C) 1989 by Jef Poskanzer.

DOCUMENT SOURCE

       This  manual  page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation
       is at

              http://netpbm.sourceforge.net/doc/pgmramp.html

netpbm documentation                            15 February 2014                          Pgmramp User Manual(1)