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). Any-
thing in between specifies a smooth blend between the two images.
The two images must have the same dimensions and the same maxval. Be-
fore 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 us-
ing 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 relationship between pixels is differ-
ent 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 programs based on libnetpbm (See
]8;;index.html#commonoptions\ Common Options]8;;\ .)
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)
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