FANT(1) UNIX System V (Dec 4, 1990) FANT(1)
NAME
fant - perform simple spatial transforms on an image
SYNOPSIS
fant [ -a angle ] [ -b blurfactor ] [ -o outfile ] [ -p xoff
yoff ] [ -s xscale yscale ] [ -S xsize ysize ] [ -v ] [
infile ]
DESCRIPTION
Fant rotates or scales an image by an arbitrary amount. It
does this by using pixel integration (if the image size is
reduced) or pixel interpolation if the image size is
increased. Because it works with subpixel precision,
aliasing artifacts are not introduced (hah! see BUGS). Fant
uses a two-pass sampling technique to perform the
transformation. If infile is "-" or absent, input is read
from the standard input.
OPTIONS
-a angle
Amount to rotate image by, a real number from 0 to 45
degrees (positive numbers rotate clockwise). Use
rleflip(1) first to rotate an image by larger amounts.
-b blur_factor
Control the amount of blurring in the output image. If
the blur factor is greater than one, image blurring
will increase. If the blur factor is smaller than one,
image blurring will decrease but aliasing artifacts may
be visible.
-o outfile
Specifies where to place the resulting image. The
default is to write to stdout. If outfile is "-", the
output will be written to the standard output stream.
-p xoff yoff
Specifies where the origin of the image is - the image
is rotated or scaled about this point. If no origin is
specified, the center of the image is used.
-s xscale yscale
The amount (in real numbers) to scale an image by.
This is often useful for correcting the aspect of an
image for display on a frame buffer with non square
pixels. For this use, the origin should be specified
as 0, 0 (see -p above). If an image is only scaled in
Y and no rotation is performed, fant only uses one
sampling pass over the image, cutting the computation
time in half.
Page 1 (printed 12/1/98)
FANT(1) UNIX System V (Dec 4, 1990) FANT(1)-S xsize ysize
An alternate method of specifying the scale factors.
xsize and ysize give the desired output image size.
The -S option can not be used in combination with -a,
-p, or -s.
-v Verbose output. Primarily for debugging.
SEE ALSO
avg4(1), rleflip(1), rlezoom(1), urt(1), RLE(5),
Fant, Karl M. "A Nonaliasing, Real-Time, Spatial Transform
Technique", IEEE CG&A, January, 1986, p. 71.
AUTHORS
John W. Peterson, James S. Painter
BUGS
Fant uses a rather poor anti-aliasing filter (a triangle
filter). This is usually good enough but will exhibit
noticeable aliasing artifacts on nasty input images.
Page 2 (printed 12/1/98)
