rotate, transpose - re-orient an image
fb/rotate angle [ input ]
fb/transpose [ -vhadrlui ] [ -ox y ] [ input ]
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
-a reflects the image through its ascending diagonal.
-v reflects the image left-to-right through its vertical center
-h inverts the image top-to-bottom through its horizontal center
-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/resample 48 >tiny
makes a tiny 4848 version of a big picture.
Very large images may not fit in memory. The result of rotate is not