-double *filter_generate(int filt_type, double bw, double xmin, double xmax, int n, double param, int domain, int numint);
-void image_filter_init(IMAGE *im, int domain, double bw, int filt_type, double filt_param, int opt_trace);
-/* im_draw.c */
-void image_show(IMAGE *im, int nxcell, int nycell, double densmin, double densmax, bool disp_scale);
-int image_paint(int dev, IMAGE *im, int xmin, int ymin, int nxcell, int nycell, double densmin, double densmax, bool disp_scale);
-int gs_image(GREYSCALE *gs, IMAGE *im, double densmin, double densmax, bool disp_scale);
-void paint_cscale(GREYSCALE *gs, int nx, int ny);
-GREYSCALE *gs_init(int dev, int xmin, int ymin, int nxcell, int nycell);
-void gs_pixel(GREYSCALE *gs, int x, int y, int gs_level);
-void gs_set_pos(GREYSCALE *gs, int x, int y);
-void gs_set_at_addr(GREYSCALE *gs, int gs_level);
-void gs_set_color_scale(void);