NAME

rotate, transpose - re-orient an image

SYNOPSIS

fb/rotate angle [ input ]

fb/transpose [ -vhadrlui ] [ -ox y ] [ input ]

DESCRIPTION

Rotate rotates the image in its input picture file (default standard input) clockwise by angle degrees, writing the resulting picture file on standard output.

Transpose turns its input picture file on its side by reflection through its major (descending from left to right) diagonal, writing the resulting picture file on standard output. If no file name is given, the picture is read from standard input. Options yield all possible symmetries of the square grid:

-d

reflects the image through its descending diagonal (the default).

-a

reflects the image through its ascending diagonal.

-v

reflects the image left-to-right through its vertical center line.

-h

inverts the image top-to-bottom through its horizontal center line.

-r

rotates the image to the right (clockwise) 90 degrees.

-l

rotates the image to the left (counterclockwise) 90 degrees.

-u

rotates the image upside down (180 degrees).

-i

identity transformation (for completeness only.)

-o x y

translates by (x,y). Without -o, the input and output files have the same upper-left corner.

Transpose is particularly useful to convince programs that work on the rows of a picture file to operate on columns. For example

fb/transpose big |

	fb/resample 48 |

	fb/transpose |

	fb/resample 48 >tiny

makes a tiny 48&215;48 version of a big picture.

SOURCE

/sys/src/fb/rotate.c
/sys/src/fb/transpose.c

SEE ALSO

picfile(9.6), resample(9.1)

BUGS

Very large images may not fit in memory. The result of rotate is not anti-aliased.