NAME
im_zone, im_fzone - creates a zone plate
SYNOPSIS
#include <vips/vips.h>
int im_zone(image, size)
IMAGE *image;
int size;
int im_fzone(image, size)
IMAGE *image;
int size;
DESCRIPTION
im_fzone() creates a float one band image of a zone plate of size size
by size. Pels are in the range [-1,+1]. The zone plate has spatial
frequencies increasing from 0 the center (at size/2, size/2) up to
infinity at the edges. size must be positive and even.
im_zone() behaves exactly as im_fzone(), but writes a FMTUCHAR image
scaled to the range 0-255.
RETURN VALUE
The function returns 0 on success and -1 on error.
SEE ALSO
im_grey(3), im_fgrey(3).
COPYRIGHT
N. Dessipris
AUTHOR
N. Dessipris - 10/05/1991
10 May 1991