pammixmulti - Man Page

blend together multiple PAM images

" "netpbm documentation"



 [--randomseed integer]
 filename ...

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


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."


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:


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=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.


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.


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.


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


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

    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


pammixmulti was new in Netpbm 10.85 (December 2018).


Copyright 2018 Scott Pakin,

See Also

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

Table Of Contents

Document Source

This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation is at

Referenced By


18 November 2018