raster_colormap
extern struct raster_colormap* raster_colormap_alloc ARGS(( int length ));
extern struct raster_colormap* raster_colormap_get ARGS(( struct raster* r ));
extern int raster_colormap_set ARGS(( struct raster* r, struct raster_colormap* cm ));
extern void raster_colormap_free ARGS(( struct raster_colormap* cm ));