pbmplus �Υ��ޥ��:pnmscale, pnmreduce, pnmenlarge
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pbmplus �Υ��ޥ��:pnmrotate
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pbmplus �Υ��ޥ��:pnmflip
pbmplus �Υ��ޥ��:pnmcrop, pnmmargin
pbmplus �Υ��ޥ��:pnmshear
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P = | {(i + 1) - u}{(j + 1) - v} Pi,j |
+ {(i + 1) - u}{v - j}Pi,j+1 | |
+ {u -i}{(j + 1) - v}Pi+1,j | |
+ {u -i}{v - j}Pi+1,j+1 |