Annotated edit history of
pnmrotate(1) version 1, including all changes.
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perry |
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pnmrotate |
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!!!pnmrotate |
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NAME |
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SYNOPSIS |
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DESCRIPTION |
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REFERENCES |
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SEE ALSO |
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AUTHOR |
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---- |
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!!NAME |
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pnmrotate - rotate a portable anymap by some angle |
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!!SYNOPSIS |
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__pnmrotate__ [[__-noantialias__] ''angle'' |
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[[''pnmfile''] |
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!!DESCRIPTION |
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Reads a portable anymap as input. Rotates it by the |
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specified angle and produces a portable anymap as output. If |
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the input file is in color, the output will be too, |
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otherwise it will be grayscale. The angle is in degrees |
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(floating point), measured counter-clockwise. It can be |
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negative, but it should be between -90 and 90. Also, for |
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rotations greater than 45 degrees you may get better results |
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if you first use ''pnmflip'' to do a 90 degree rotation |
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and then ''pnmrotate'' less than 45 degrees back the |
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other direction |
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The rotation algorithm is Alan Paeth's three-shear method. |
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Each shear is implemented by looping over the source pixels |
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and distributing fractions to each of the destination |
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pixels. This has an |
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-noantialias__ flag. This does |
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the shearing by moving pixels without changing their values. |
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If you want anti-aliasing and don't care about the precise |
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colors, but still need a limited *number* of colors, you can |
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run the result through ''ppmquant''. |
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All flags can be abbreviated to their shortest unique |
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prefix. |
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!!REFERENCES |
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!!SEE ALSO |
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pnmshear(1), pnmflip(1), pnm(5), ppmquant(1) |
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!!AUTHOR |
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Copyright (C) 1989, 1991 by Jef Poskanzer. |
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