FANT(1)                                                 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  pre-
       cision,  aliasing artifacts are not introduced (hah! see
       BUGS).  Fant uses a two-pass sampling technique to  per-
       form  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 clock-
              wise).  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.

       -S xsize ysize
              An  alternate method of specifying the scale fac-
              tors.  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  Trans-
       form 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.



                          Dec 4, 1990                   FANT(1)
