man > ppmmix(1)

Ppmmix User Manual(1)                  General Commands Manual                 Ppmmix User Manual(1)

NAME
       ppmmix - blend together two PPM images


SYNOPSIS
       ppmmix fadefactor ppmfile1 ppmfile2


DESCRIPTION
       This program is part of Netpbm(1).

       ppmmix reads two PPM images as input and mixes them together using the specified fade factor.
       The  fade  factor may be in the range from 0.0 (only ppmfile1's image data) to 1.0 (only ppm‐
       file2's image data).  Anything in between specifies a smooth blend between the two images.

       The two images must have the same dimensions and the same maxval.  Before Netpbm 10.54 (March
       2011), they must also have the same type (PBM/PGM/PPM).

       The fade factor is applied to brightness, not light intensity.  That means for  example  that
       if you have a series of images you generated using ppmmix of a black and a white image with a
       linearly  increasing  fade  factor,  you will see an image getting linearly brighter, but the
       light intensity will increase faster at the end.  That is because it requires more  intensity
       change  at the bright end of the scale than at the dark end for the human eye to perceive the
       same brightness change.  This also means that if the original images aren't  all  one  color,
       the  mixed  image  is distorted, since the intensity relationship between pixels is different
       from the original image.

       pamcomp is a more general alternative.  It allows you to mix images of different size and  to
       have  the fade factor vary throughout the image (through the use of a transparency mask).  It
       does not have the same-maxval and same-type restrictions.   It  mixes  light  intensity,  not
       brightness.


OPTIONS
       There  are no command line options defined specifically for ppmmix, but it recognizes the op‐
       tions common to all programs based on libnetpbm (See ]8;;index.html#commonoptions\ Common Options]8;;\ .)


SEE ALSO
       pamcomp(1), pammixmulti(1), ppm(1)


AUTHOR
       Copyright (C) 1993 by Frank Neumann

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/ppmmix.html

netpbm documentation                        23 March 2010                      Ppmmix User Manual(1)