Archived posting to the Leica Users Group, 1999/09/24

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Subject: [Leica] Re: Low Pressure Sodium
From: "Michael D. Turner" <mike@lcl-imaging.com>
Date: Sat, 25 Sep 1999 02:20:01 +0000

Mark Rabiner wrote:

>
> The issue in your first paragraph is I think one of discontinuous spectrum.
> Scattered Holes where certain colors don't exist at all.
> IN your second paragraph it's one of balance. All the colors are there but in
> different amounts. Am I right? A warm verses a cold bias.
> Mark Rabiner

My point in the 2nd paragraph was that even with a continuous spectrum light source,
it is still possible, in fact, likely, to have too little light recorded at one end or
the other of the spectrum. Attempting to correct a non-linear bias with a large linear
correction doesn't work. Zero x zero = zero. Low-level detail plus noise x large
linear correction = large error = ugly. Pretty much the same situation you have in
dealing with discrete light sources.
- -Mike