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RedHat 9 (Linux i386) - man page for pnmshear (redhat section 1)

pnmshear(1)			     General Commands Manual			      pnmshear(1)

NAME
       pnmshear - shear a portable anymap by some angle

SYNOPSIS
       pnmshear [-noantialias] angle [pnmfile]

DESCRIPTION
       Reads  a portable anymap as input.  Shears it by the specified angle and produces a porta-
       ble anymap as output.  If the input file is in color, the output will be too, otherwise it
       will be grayscale.  The angle is in degrees (floating point), and measures this:
	   +-------+  +-------+
	   |	   |  |\       \
	   |  OLD  |  | \  NEW	\
	   |	   |  |an\	 \
	   +-------+  |gle+-------+
       If the angle is negative, it shears the other way:
	   +-------+  |-an+-------+
	   |	   |  |gl/	 /
	   |  OLD  |  |e/  NEW	/
	   |	   |  |/       /
	   +-------+  +-------+
       The angle should not get too close to 90 or -90, or the resulting anymap will be unreason-
       ably wide.

       The shearing is implemented by looping over the source pixels and  distributing	fractions
       to  each of the destination pixels.  This has an "anti-aliasing" effect - it avoids jagged
       edges and similar artifacts.  However, it also means that the original colors or gray lev-
       els  in the image are modified.	If you need to keep precisely the same set of colors, you
       can use the -noantialias flag.  This does the shearing by moving pixels	without  changing
       their  values.	If  you  want  anti-aliasing and don't care about the precise colors, but
       still need a limited *number* of colors, you can run the result through ppmquant.

       All flags can be abbreviated to their shortest unique prefix.

SEE ALSO
       pnmrotate(1), pnmflip(1), pnm(5), ppmquant(1)

AUTHOR
       Copyright (C) 1989, 1991 by Jef Poskanzer.

					 12 January 1991			      pnmshear(1)


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