ppmmix(1) - phpMan

Ppmmix User Manual(0)                                                       Ppmmix User Manual(0)



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 fac-
       tor.  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 relation-
       ship 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.


SEE ALSO
       pamcomp(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(0)

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