Re: [APML] film flat fielding

[Wei-Hao Wang <whwang@gmail.com>]

Hi Jason, 

You are right.  After I averaged five images from different
directions, I still see
some residual gradient.  I rotated the final image by 180d and merged it back 
with the unrotated image.  Then I flip it and merge it back.  This assumes that
the vignetting pattern is symmetric about x and y axes.  I guess this 
assumption is not too bad.

Wei-Hao


On Mon, 26 Jul 2004 07:39:56 -0700, Lane, Jason R <jason.lane@navy.mil> wrote:
> Hi Wei-Hao,
> 
> That's a helpful little article there.  I think sky gradient could be removed by taking an image of blank sky, rotating camera 180 and taking a 2nd image, then averaging those 2.
> 
> -Jason
> 

-- 
________________________________________________________________
Wei-Hao Wang  :)

Institute for Astronomy at University of Hawaii

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2680 Woodlawn Drive         Personal Website:
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