Re: Colorsync-users Digest, Vol 5, Issue 340
Re: Colorsync-users Digest, Vol 5, Issue 340
- Subject: Re: Colorsync-users Digest, Vol 5, Issue 340
- From: Graeme Gill <email@hidden>
- Date: Tue, 30 Sep 2008 16:14:50 +1000
email@hidden wrote:
reflection data. And of course, changing modes clues device what transform to use. If
you have any doubt, the patent and technical literature in the instrument
field is replete with examples on how to do these kinds of mathematical mappings.
Its the camera profiling example on steroids...
Having examined what's going on inside a rather popular spectro
(the Eye One Pro), I see no such magic. There is no mode
shift apart from the obvious (one set of calibration weights
for emissive, a second concatenated set for reflective).
Given the way it's technical specifications read, I'm struggling
to see how such optimization can be slipped into the equation,
apart from the particular wavelength re-sampling co-efficients,
and they show no signs of being optimized at different wavelengths
(ie. the filter shape is constant).
I would suspect the vast majority of patents aren't actually
being used in any real products (they're just nice ideas that
may or may not work in practice).
<<Yes spectrometers have smaller bands,
so for a given amount of light each band has a lower S/N, but there
as precisely as many more bands as they are narrow, canceling out the
overall effect.>>
Unfortunately, not always does the sum of the parts equal the whole because
of non-ideal design particularly: SNR at a given sample, error propogation
(errors square by the gains squared in the transforms when trying to "re-assemble"
the colorimetry that the colorimeter measures more directly with smaller
sigmas and gains in the transform) and many other reasons that probably are not of
interest to this list!
Sorry, I still don't see the logic of this argument, unless one introduces
quantum and/or quantization error effects (you'd need some
maths to convince me), and my point was that any such effect is likely to
be much less than the the major difference, which is the difference in
area (hence amount of light) being sampled, and as such, it's misleading
suggest the first as the primary issue.
Graeme Gill.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden