im_contrast_surface3

Usage

#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 );

Overview

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.