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  ppmfile2'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  options  common
       to all programs based on libnetpbm (See  Common Options .)

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)