Synopsis

void                subsample_region                    (PixelRegion *srcPR,
                                                         PixelRegion *destPR,
                                                         gint subsample);
void                subsample_indexed_region            (PixelRegion *srcPR,
                                                         PixelRegion *destPR,
                                                         const guchar *cmap,
                                                         gint subsample);