void hard_mask(LPDWORD image_in,LPDWORD image_out,
			   LPBYTE image_key,int thresh);
void synth(LPDWORD image_in_front,LPDWORD image_in_back,
		   LPDWORD image_out,LPBYTE image_key);
void soft_mask(LPDWORD image_in,LPDWORD image_out,
			   LPBYTE image_key,int thd_min,int thd_max);
void s_synth(LPDWORD image_in_front,LPDWORD image_in_back,
			 LPDWORD image_out,LPBYTE image_key);
void histgram_Hue(double *hue,long hist[360]);
void thresh_Hue(LPDWORD image_in,LPDWORD image_out,
			  double *hue,int hue_min,int hue_max);