Re: ProfileMaker 5
Re: ProfileMaker 5
- Subject: Re: ProfileMaker 5
- From: Graeme Gill <email@hidden>
- Date: Mon, 21 Aug 2006 17:07:10 +1000
Roger Breton wrote:
Can't this be
measured, indirectly, if I have the T spectroscan and measure in
transmissive mode? Just a thought. I gather that what I'm really after is
the spectral transmission characteristics of the Lino D65 filter (it must
the same as in the SpectroEye?)....
The two ways I tried (No 'T' needed..):
1) Calibrate and measure the white reference through the U filter [Uref].
Change the filter to D65, and re-measure the white reference without
recalibrating [D65Ref].
Compute the filter as sqrt(D65Ref/URef)
2) I set up a diffuser illuminated by a Quartz Halogen lamp,
and measured the spectrum of this with the spectrolino in
emissive mode, with no filter fitted [RefSpec]
I fitted the D65 filter and measured again [D65Spec]
Computed the filter as D65spec/RefSpec.
To compute an estimated simulated D65, multiply the filter by
the A spectrum. Both these methods agreed with each other.
Ah! This is worth investigating. Wonder why FOGRA not suggesting measurwing
with a D65 filter since they are so pushy for some kind of UV filtration in
the next ISO 5-3 standard (that's what I heard)?
Because this is the opposite direction to fitting a UV filter ?
Graeme Gill.
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