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
K. Martinez 13/4/92 13 April 1992