im_fav4 - averages four frames
#include <vips/vips.h>
int im_fav4(in, out)
IMAGE **in, *out;
im_fav4 averages four input VIPS images, which must be unsigned byte
images with any number of bands. This is useful for noise reduction by
grabbing 4 frames and averaging them. With 7 bit images this will give
quite a convincing eighth bit.
returns 0 on success or -1 on error
add(1)
K. Martinez 13/4/92
13 April 1992