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im_grad_x, im_grad_y - find horizontal or vertical differences
#include <vips/vips.h>
int im_grad_x( IMAGE *in, IMAGE *out );
int im_grad_y( IMAGE *in, IMAGE *out );
im_grad_x(3)
generates
an image where the value of each pixel is the difference between horizontally
ajacent pixels in the input image. The output has the same height as the
input and one pixel less width.
im_grad_y(3)
generates an image where the
value of each pixel is the difference between vertically ajacent pixels
in the input image. The output has the same width as the input and one
pixel less height.
In both cases, the input can be any uncoded integer type,
and the output is signed 32 bit integer.
The functions returns
0 on success and -1 on error.
Copyright 2008, Nottingham Trent University.
Tom Vajzovic
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