1Ppmmix User Manual(0)                                    Ppmmix User Manual(0)
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NAME

6       ppmmix - blend together two PPM images
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SYNOPSIS

10       ppmmix fadefactor ppmfile1 ppmfile2
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DESCRIPTION

14       This program is part of Netpbm(1).
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16       ppmmix  reads two PPM images as input and mixes them together using the
17       specified fade factor.  The fade factor may be in the  range  from  0.0
18       (only ppmfile1's image data) to 1.0 (only ppmfile2's image data).  Any‐
19       thing in between specifies a smooth blend between the two images.
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21       The two images must have the  same  dimensions  and  the  same  maxval.
22       Before  Netpbm  10.54  (March  2011), they must also have the same type
23       (PBM/PGM/PPM).
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25       The fade factor is applied to brightness, not  light  intensity.   That
26       means  for  example  that  if you have a series of images you generated
27       using ppmmix of a black and a white image with  a  linearly  increasing
28       fade  factor,  you will see an image getting linearly brighter, but the
29       light intensity will increase faster at the end.  That  is  because  it
30       requires  more  intensity change at the bright end of the scale than at
31       the dark end for the human eye to perceive the same brightness  change.
32       This  also  means that if the original images aren't all one color, the
33       mixed image is distorted, since the intensity relationship between pix‐
34       els is different from the original image.
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36       pamcomp  is a more general alternative.  It allows you to mix images of
37       different size and to have the fade factor vary  throughout  the  image
38       (through  the  use of a transparency mask).  It does not have the same-
39       maxval and same-type  restrictions.   It  mixes  light  intensity,  not
40       brightness.
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OPTIONS

44       There  are no command line options defined specifically for ppmmix, but
45       it recognizes the options common to all  programs  based  on  libnetpbm
46       (See
47        Common Options ⟨index.html#commonoptions⟩ .)
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SEE ALSO

51       pamcomp(1), pammixmulti(1), ppm(1)
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AUTHOR

55       Copyright (C) 1993 by Frank Neumann
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DOCUMENT SOURCE

58       This  manual  page was generated by the Netpbm tool 'makeman' from HTML
59       source.  The master documentation is at
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61              http://netpbm.sourceforge.net/doc/ppmmix.html
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63netpbm documentation             23 March 2010           Ppmmix User Manual(0)