function magpower, arr, power

;+
; NAME:
; 	MAGPOWER
;
; PURPOSE:
; 	To manipulate with contrast of an image
;
; CATEGORY:
; 	Image processing.
;
; CALLING SEQUENCE:
; 	New_array = magpower(array, power)
;
; INPUTS:
; 	Array: viewed image
; 	Power: degree to be applied separately to positive and negative values of the 
; 	image.
;
; OPTIONAL INPUT PARAMETERS:
; 	None
;
; KEYWORD PARAMETERS:
; 	None
;
; OUTPUTS:
; 	Nonlinearly transformed image
;
; COMMON BLOCKS:
; 	None.
;
; SIDE EFFECTS:
; 	None.
;
; RESTRICTIONS:
; 	None.
;
; PROCEDURE:
; 	New_array  = (array > 0)^power -(-array > 0)^power
;  
; MODIFICATION HISTORY:
;
;	UMD, 2001.
;	Victor Grechnev (grechnev@iszf.irk.ru) & Vladimir Garaimov (gvi@astro.umd.edu)
;		Initially written.
;
;	ISTP SD RAS, Jul, 2002.
;	Natalia Meshalkina (nata@iszf.irk.ru): Help added.
; 
; -

if n_params() eq 1 then power = 0.3

return, (arr > 0.)^power -(-arr>0.)^power

	end