;++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
;
;*NAME:    
;	
;	pro p3d_bias_file
;
;*VERSION:
;
;	$Id$
;
;*CATEGORY:
;		
;	P3d online data reduction	
;		
;*CALLING SEQUENCE:
;
;	p3d_bias_file,filename,out,xclean,yclean,xsmo,ysmo,$
;	         const=const,xconst=xconst,yconst=yconst
;
;*INPUT:
;
;	filename   filename of the 2D raw bias image
;	
;*OUTPUT:
;
;	out	   2D modelled bias image
;
;*PARAMETERS:
;
;	xclean	(2*xclean+1) is the xsize of a box used for median filtering
;	yclean	(2*yclean+1) is the ysize of a box used for median filtering
;	xsmo	(2*xsmo+1) is the xsize of a box used for mean filtering
;	ysmo	(2*ysmo+1) is the ysize of a box used for mean filtering
;
;*KEYWORDS:
;
;	const	(0/1) flag is set to 1 if the output is a constant bias level
;		DEFAULT: const=0
;	xconst  (0/1) flag is set to 1 if the output is constant in x-direction
;	yconst  (0/1) flag is set to 1 if the output is constant in y-direction
; 
;*CALLED FUNCTIONS:
;
;*CALLED PROCEDURES:
;
;	med_smo		mean_smo
;
;*PURPOSE:
;
;	The procedures models a bias image from a noisy and with bad pixels 
;	contaminated raw bias frame. The input image is first cleaned by a 
;	median filtering algorithm and is then smoothed via a mean filter. 
;	Optional the bias level in the x-, y- directions can be assumed to 
;	be constant.
;
;*MODIFICATION HISTORY:
;
;	TBE: 23/05/2002 - VERSION 1.0	initial programming   
;   
;          
;*AUTHORS:
;
;	TBE		Thomas Becker	Astrophysikalisches Institut Potsdam
;					An der Sternwarte 16
;					D-14481 Potsdam
;                                       email: tbecker@aip.de
;					Tel. (049) 331/7499 - 414
;
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