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im_eye, im_feye - creates a pattern which shows the spatial response
of the human visual system
#include <vips/vips.h>
int im_eye(image,
xsize, ysize, factor)
IMAGE *image;
int xsize, ysize;
double factor;
int im_feye(image, xsize, ysize, factor)
IMAGE *image;
int xsize, ysize;
double factor;
im_feye() creates an one band float image with
pels in [-1,+1] of a pattern which has the following properties:
- the spatial frequency increases from left to right.
- the grey level intensity decreases from top to bottom.
The sizes of the produced image are determined by the entered arguments
xsize and ysize. The variable factor which should be between 0 and 1, determines
the number of maximum spatial frequencies present along the horizontal
direction.
im_eye() behaves exactly as im_feye(), but scales the output
to [0,255].
The function returns 0 on success and -1 on error.
im_grey(3)
, im_zone(3)
.
N. Dessipris
N. Dessipris -
10/05/1991
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