Manual: ppmmix

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 ppmfile2's image data).  Anything in between speci‐
       fies 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 re‐
       quires 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 dis‐
       torted, 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	pro‐
       grams 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)