extern int npix[]; /* Number of pixels along each axis of real image */
extern int zoom, size[];
extern float Hclip[], Sclip[], Vclip[];
extern float *Himage, *Simage, *Vimage;
extern char *uidlocation, *image_name, *helplocation;
extern char *Hname, *Sname, *Vname;
extern unsigned long graypix, blackpix;
extern int Hmin, Hmax, Smin, Smax, Vmin, Vmax;