pnmshear

pnmshear

NAME SYNOPSIS DESCRIPTION SEE ALSO AUTHOR

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 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), 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 unreasonably wide.

The shearing is implemented by looping over the source pixels and distributing fractions to each of the destination pixels. This has an

• 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.