Re: new UMAX-Patch available

Rogier Wolff (R.E.Wolff@BitWizard.nl)
Wed, 27 May 1998 07:59:50 +0200 (MET DST)

William L. Sebok wrote:
>
> Oliver.Rauch@Wolfsburg.DE says:
>
> > It looks like a white calibration table for each pixel of the ccd that
> > is used for the requested scan. So - I think - if a CCD-pixel has an other
> > output level than the other CCD-pixels, it can be corrected that way.
> > May be it is possible to do a kind of highlight-function by that.

> This sort of correction has to be done very carefully when one uses
> a ccd camera for Astronomical purposes. It's called a "flat-field"
> calibration and was often done by taking pictures of the inside of
> the closed telescope dome. In fact sometimes it was hard to see
> things until this correction was done. I'm not surprised that a way
> of doing this has been provided in a scanner that uses a ccd
> detector.

My scanner, the Tamarack 12000C, does this on its own whenever you tell
it to start scanning. Pain in the A**: It does this EVERY time you tell
it to scan, not just the first time during every session.

The astronomer types also trust the CCD to remain for the twenty
minutes that they use to take a picture so why can't my desktop
scanner?

Roger. 

-- 
If it's there and you can see it, it's REAL      |___R.E.Wolff@BitWizard.nl  |
If it's there and you can't see it, it's TRANSPARENT |  Tel: +31-15-2137555  |
If it's not there and you can see it, it's VIRTUAL   |__FAX:_+31-15-2138217  |
If it's not there and you can't see it, it's GONE! -- Roy Wilks, 1983  |_____|



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