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  ⟨index.html#commonoptions⟩  ),  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