pnmrotate(1) General Commands Manual pnmrotate(1) NAME pnmrotate - rotate a portable anymap by some angle SYNOPSIS pnmrotate [-noantialias] angle [pnmfile] DESCRIPTION Reads a portable anymap as input. Rotates it by the specified angle and produces a portable 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), measured counter-clockwise. It can be negative, but it should be between -90 and 90. Also, for rota- tions greater than 45 degrees you may get better results if you first use pnmflip to do a 90 degree rotation and then pnmrotate less than 45 degrees back the other direction The rotation algorithm is Alan Paeth's three-shear method. Each shear is implemented by looping over the source pixels and distributing frac- tions 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 levels 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. REFERENCES "A Fast Algorithm for General Raster Rotation" by Alan Paeth, Graphics Interface '86, pp. 77-81. SEE ALSO pnmshear(1), pnmflip(1), pnm(5), ppmquant(1) AUTHOR Copyright (C) 1989, 1991 by Jef Poskanzer. 12 January 1991 pnmrotate(1)
Czas wygenerowania: 0.00012 sek.
Created with the man page lookup class by Andrew Collington.
Based on a C man page viewer by Vadim Pavlov
Unicode soft-hyphen fix (as used by RedHat) by Dan Edwards
Some optimisations by Eli Argon
Caching idea and code contribution by James Richardson
Copyright © 2003-2021 Linux.pl
Hosted by Hosting Linux.pl