cmp_ppm(1)

NAME
cmp_ppm - a program to create the difference image of two PGM images

SYNOPSIS
cmp_ppm [ -c name ] [ -h ] [ -m number ] [ -o ofile ] -i ifile file

DESCRIPTION
cmp_ppm is a program to create the difference image of two PPM (portable pixmap) RGB color images. To compare PGM (portable graymap) grayscale images, use the cmp_pgm program.

The color components to compare are specified with the -c name option, where name is one of the following:

red The red color component.

green
    The green color component.

blue
    The blue color component.

Multiple color components are allowed. Specifying only the inital letter of a color component is sufficient. Per default cmp_ppm compares the luminance value of the images. This operation may be selected explicitly with the -c luminance option.

If file or ofile is not specified, then standard input or standard output is used.

OPTIONS

-c name
    Specifies color component(s) or luminance to compare. Default: luminance.

-h  Print a help message.

-i ifile
    The original image. Mandatory.

-m number
    Multiplication factor to magnify differences between the to original and input image. Default value: 16.

-o ofile
    Output image file to contain the difference image in PPM format.

file
    Input image that is compared against ifile. Default: standard input.

OUTPUT
The difference image in PPM format is written to standard output or, optionally, to ofile.

AUTHOR
Peter Meerwald. Email bug reports to pmeerw@cosy.sbg.ac.at.

AVAILABILITY
The most recent released version of cmp_ppm is always available at http://www.cosy.sbg.ac.at/~pmeerw/Watermarking or via anonymous ftp from ftp.cosy.sbg.ac.at in the directory /pub/people/pmeerw/Watermarking.

SEE ALSO
cmp_ppm (1)