Re: light source for transmissive measurment (formally New spectral tool)
Re: light source for transmissive measurment (formally New spectral tool)
- Subject: Re: light source for transmissive measurment (formally New spectral tool)
- From: Graeme Gill <email@hidden>
- Date: Mon, 02 Mar 2009 12:02:27 +1100
Mike Eddington wrote:
Wouldn't the best light source to use for transmissive measurment be the actual light
source used in the backlight (assuming one has access to it), regardless, or maybe
because of any gaps in the spectrum? Or would this fall under a "practical" versus
"optimal" argument.
The problem is that this approach runs into numerical issues. You are trying
to measure transmissive using a light source that has low output at some
wavelengths. This means that the instrument measures a low level of light,
and then you divide by a small number (the known illuminant output at
that wavelength), possibly blowing it up to some large, almost random number.
You then (later) try and multiply by that number (when you model the transmission
being illuminated by the same light source), and the result may or may not return
to the original one the instrument read.
Far better is to measure the system as is, by measuring the emission
value rather than transmission (hence the idea of reading strips in
emission mode I referred to in a previous post).
ie. you treat the whole system like it was an emissive display.
Graeme Gill.
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