Re: [APML] Scorpius, Sagittarius, and the Milky Way

[<apml@andreasroerig.de>]

Hi Wei-Hao,

what a great image. Wonderful work and an interesting description of
your processing methods.

Best regards
Andreas

:=============================
: Andreas Roerig
: http://www.andreasroerig.de


Wei-Hao Wang <whwang@gmail.com> schrieb am 05.07.2004, 10:11:53:
> ALOHA,
> 
> A new image is in 
> http://www.ifa.hawaii.edu/~wang/gallery/picutres/sco_sgi_milkyway.htm
> 
> To correct the vignetting pattern, I used a little crappy but quick
> flat field method.
> 
> As I introduced my flat field technique to you about half year ago, I
> took several
> images of daytime sky and average them to make a flat image.  The old way is
> to nonlinearly match this flat with the sky background in a real
> astronomical image
> and then divide the image with the matched flat image.  This method works quite
> well.  I had showed the results on my Orion mosaic to you.  However,
> this technique
> may be a little difficult for most people since it requires some computer
> programming.
> 
> In order to see if things could be more simple, I divide the image with the flat
> directly (without any background matching).  The result is the image above.
> I have to say, this flat fielding is not perfect but the residual
> vignettign pattern
> can be so easily fixed in PhotoShop.  I think this is worth trying. 
> You don't need
> to write a C++ program.  All you need is to take a picture of daytime sky and 
> find a image processing software that does division (PhotoShop doesn't).
> 
> Cheers,
> 
> Wei-Hao
> 
> -- 
> ________________________________________________________________
> Wei-Hao Wang  :)
> 
> Institute for Astronomy at University of Hawaii
> 
> Address:                       
> 2680 Woodlawn Drive         Personal Website:
> Honolulu, HI 96822             http://www.ifa.hawaii.edu/~wang
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