Pamstretch User Manual(0)             Pamstretch User Manual(0)



Table Of Contents


NAME
       pamstretch  - scale up a PNM or PAM image by interpolat-
       ing between pixels.


SYNOPSIS
       pamstretch

       [-xscale=X]

       [-yscale=Y] [-blackedge]

       [-dropedge]

       N

       [infile]

       You can use  the  minimum  unique  abbreviation  of  the
       options.   You  can use two hyphens instead of one.  You
       can separate an option name from its  value  with  white
       space instead of an equals sign.


DESCRIPTION
       This program is part of Netpbm(1).

       pamstretch  scales up pictures by integer values, either
       vertically, horizontally, or both.  pamstretch   differs
       from pamscale and pnmenlarge in that when it inserts the
       additional rows and columns, instead of making  the  new
       row  or  column a copy of its neighbor, pamstretch makes
       the new row  or  column  an  interpolation  between  its
       neighbors.  In some images, this produces better looking
       output.

       To scale up to non-integer pixel sizes,  e.g.  2.5,  try
       pamstretch-gen(1)instead.

       Options  let  you  select alternative methods of dealing
       with the right/bottom edges of the picture.   Since  the
       interpolation  is  done  between the top-left corners of
       the scaled-up pixels, it's not obvious what to  do  with
       the  right/bottom  edges.   The  default behaviour is to
       scale those up without  interpolation  (more  precisely,
       the  right edge is only interpolated vertically, and the
       bottom edge  is  only  interpolated  horizontally),  but
       there  are  two  other  possibilities,  selected  by the
       blackedge and dropedge options.


PARAMETERS
       The N parameter is the scale factor.  It is  valid  only
       if  you don't specify -xscale or -yscale.  In that case,
       pamstretch scales in both dimensions and  by  the  scale
       factor N.


OPTIONS
       -xscale=X
              This  is  the  horizontal  scale  factor.  If you
              don't specify this, but  do  specify  a  vertical
              scale factor, the horizontal scale factor is 1.


       -yscale=Y
              This  is the vertical scale factor.  If you don't
              specify this, but do specify a  horizontal  scale
              factor, the vertical scale factor is 1.


       -blackedge
              interpolate to black at right/bottom edges.


       -dropedge
              drop  one  (source)  pixel at right/bottom edges.
              This is arguably more logical  than  the  default
              behaviour, but it means producing output which is
              a slightly odd size.




BUGS
       Usually produces fairly ugly output for PBMs.  For  most
       PBM  input  you'll  probably  want to reduce the `noise'
       first using something like pnmnlfilt(1).


SEE ALSO
       pamstretch-gen(1),  pnmenlarge(1),  pamscale(1),  pnmnl-
       filt(1)


AUTHOR
       Russell Marks (russell.marks@ntlworld.com).



netpbm documentation    11 November 20Pamstretch User Manual(0)
