NAME

       pammixmulti - blend together multiple PAM images

SYNOPSIS

       pammixmulti
         [-blend=average|alpha-weighted|random|mask]
         [-maskfile=filename]
         [-stdev=number]
         [-randomseed integer]
         filename ...

       Minimum  unique  abbreviation  of  an option is acceptable. You can use double hyphen instead of a single
       hyphen to denote options. You can use white space in place of the equals sign to separate an option  name
       from its value.

DESCRIPTION

       This file is part of Netpbm(1).

       pammixmulti  mixes  two  or  more  images  to  produce a new image. The program provides multiple ways to
       interpret "mix."

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably  -quiet,  see   Common
       Options ), pammixmulti recognizes the following command line options:

       -blend=average|alpha-weighted|random|mask

              This  option  specifies  how  the  input images should be mixed to produce the output image.  With
              -blend=average (the default), each pixel in the output is produced by averaging the  corresponding
              pixels  from  all  the  input  images.   With  -blend=alpha-weighted,  each pixel in the output is
              produced by taking a weighted average of the corresponding pixels from all the input images, using
              each pixel's alpha (opaqueness) level as its weight.  With -blend=random, each pixel in the output
              is produced by selecting the corresponding pixel from one of the input images, chosen at random on
              a per-pixel basis.  With -blend=mask, each pixel in the output is produced by a  weighted  average
              of  the  corresponding  pixels  from  all  the  input  images  based  on the grayscale level of an
              additional mask image.

              -alpha-weighted was new in Netpbm 11.09 (December 2024).

       -maskfile=filename

              In conjunction with -blend=mask, this option names a grayscale mask file to control  the  blending
              of  each  pixel.  (If the file is not grayscale, the first channel is treated as gray).  Where the
              mask file is black, the first image is selected. Where the mask file is white, the last  image  is
              selected.  Intermediate levels of gray select intermediate images.

       -stdev=number

              When  used  with -blend=mask, this option controls how smoothly the various input images are mixed
              to produce each output pixel.  For example, consider running pammixmulti with three  input  images
              and  a  mask image that uses gray levels from 0 to 255. Given -stdev=0.0, gray levels 0-84 produce
              exclusively image 1; gray levels 85-170 produce exclusively  image  2;  and  gray  levels  171-255
              produce  exclusively image 3.  If the argument to -stdev is positive, images are blended according
              to a normal distribution.  Hence, gray levels around 85 produce  an  output  pixel  that  includes
              roughly equal amounts of the corresponding pixel from images 1 and 2 but less of the corresponding
              pixel  from  image  3.   As number tends towards the number of input images (going beyond that has
              diminishing impact), the output tends to look more like -blend=average. number defaults to 0.25.

       -randomseed integer
              This is the seed for the random number generator used with -blend=random

              Use this to ensure you get the same image on separate invocations.

ARGUMENTS

       You supply the names of the files to mix as non-option arguments.

EXAMPLES

       Average a bunch of PPM images to produce a new PAM image:
           pammixmulti input*.ppm >output.ppm

       Mix these same images by taking each pixel from a randomly selected input image:

           pammixmulti -blend=random input*.ppm >output.ppm

       Use a mask image to control the fading among input images on a pixel-by-pixel basis:

           pammixmulti -blend=mask -maskfile=mask.pgm >output.pam \
              one.pam two.pam three.pam four.pam

       Do the same but with more abrupt transitions:

           pammixmulti -blend=mask -maskfile=mask.pgm -stdev=0.0 >output.pam \
              one.pam two.pam three.pam four.pam

       and now with more gradual transitions:

           pammixmulti -blend=mask -maskfile=mask.pgm -stdev=1.0 >output.pam \
              one.pam two.pam three.pam four.pam

HISTORY

       pammixmulti was new in Netpbm 10.85 (December 2018).

AUTHOR

       Copyright 2018–2024 Scott Pakin, scott+pbm@pakin.org.

SEE ALSO

       pamcomp(1), ppmmix(1), pamarith(1), pnm(1), pam(1)

Table Of Contents

       •      SYNOPSIS

       •      DESCRIPTION

       •      OPTIONS

       •      ARGUMENTS

       •      EXAMPLES

       •      HISTORY

       •      AUTHOR

       •      SEE ALSO

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/pammixmulti.html

netpbm documentation                            18 December 2024                      Pammixmulti User Manual(1)