#include <vips/vips.h>int im_contrast_surface( IMAGE *in, IMAGE *out, int half_win_size, int spacing ); int im_contrast_surface_raw( IMAGE *in, IMAGE *out, int half_win_size, int spacing );
DESCRIPTION
These functions generate an image where the value of each pixel represents the
contrast within a square window of size 2 * half_win_size + 1 centred on the
corresponsing point in the input image.
The output is sub-sampled by a factor of spacing.
Input must be single-band uncoded uchar, WIO or PIO.
Output is single-band uncoded uint, WIO or PIO.
In
im_contrast_surface(3),
pixels beyond the edges of the input image are considered to be have the value
of the nearest pixel which is in the image.
Alternatively, in
im_contrast_surface_raw(3),
pixels within half_win_size of the edge are not calculated, and output is
smaller accordingly.
RETURN VALUE
The functions returns 0 on success and -1 on error.