1Pamdepth User Manual(0)                                Pamdepth User Manual(0)
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NAME

6       pamdepth - change the depth (color resolution) in a Netpbm image
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SYNOPSIS

10       pamdepth newmaxval [netpbmfile]
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DESCRIPTION

14       This program is part of Netpbm(1).
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16       pamdepth  reads a Netpbm image as input, changes its depth (color reso‐
17       lution), and writes out the resulting Netpbm image.   I.e.  the  output
18       has  a  different maxval from the input, but all the same colors (apart
19       from rounding error).
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21       Reducing the depth results in some loss of information.
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23       Here is an example of the effect at the image format level: Assume  you
24       start  with  an  image with maxval 100 and sample values of 50 and 100.
25       You tell pamdepth to change it to depth 150.  The output has maxval 200
26       and sample values 75 and 150.
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28       This program works on multi-image streams.
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30       Be  careful  of  off-by-one  errors  when choosing the new maxval.  For
31       instance, if you want the color values to be five bits wide, use a max‐
32       val of 31, not 32.
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34       One  important  use  of pamdepth is to convert a new format 2-byte-per-
35       sample PNM file to the older 1-byte-per-sample  format.   Before  April
36       2000,  essentially  all raw (binary) format PNM files had a maxval less
37       than 256 and one byte per sample, and many programs may rely  on  that.
38       If  you specify a newmaxval less than 256, the resulting file should be
39       readable by any program that worked with PNM files before April 2000.
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SEE ALSO

43       pnm(1), pam(1), pnmquant(1), ppmdither(1) ppmbrighten(1) pamfunc(1)
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HISTORY

47       pamdepth  was  new  in  Netpbm  10.32  (February  2006).   It  replaced
48       pnmdepth,  by  Jef  Poskanzer.   pamdepth  is  backward compatible with
49       pnmdepth and adds the ability to process arbitrary PAM images  and  the
50       ability  to  process  multi-image input streams.  pnmdepth handled only
51       PNM images and ignored all but the first in any stream.
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DOCUMENT SOURCE

54       This manual page was generated by the Netpbm tool 'makeman'  from  HTML
55       source.  The master documentation is at
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57              http://netpbm.sourceforge.net/doc/pamdepth.html
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59netpbm documentation           19 December 2013        Pamdepth User Manual(0)
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