;+
; NAME: image_shift_maskedges
; PURPOSE:
; 	When shifting an image, manipulate the bad pixel mask
; 	appropriately such that the correct edges of the shifted 
; 	image are declared bad. 
; NOTES:
; 	This doesn't worry about bad pixels in the interior of the image - 
; 	for now. This relies on rounding the shift such that it's only the
; 	fractional part and thus using the bad pixel mask for the nearest integer
; 	pixel is not such a bad idea. You still should have fixed via interpolation
; 	all bad pixels before any subpixel shifting, of course.
;
; INPUTS:
; 	badpix				bad pixel mask
; 	xshift, yshift		x and y image shifts
; 						This code assumes |x| < 1, |y| < 1
; KEYWORDS:
; OUTPUTS:
; 	Modifies the supplied badpix mask.
;
; HISTORY:
; 	Began 2004-10-21 20:27:33 by Marshall Perrin 
;-

PRO image_shift_maskedges,badpix,xshift,yshift

	sz = size(badpix)

	if xshift lt 0 then badpix[sz[1]-1,*]=0
	if xshift gt 0 then badpix[0,*]=0
	if yshift lt 0 then badpix[*,sz[2]-1]=0
	if yshift gt 0 then badpix[*,0]=0


end