[argyllcms] Re: Poor Man's Colorimeter

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 12 Jun 2015 09:51:29 -0700

On Jun 12, 2015, at 9:19 AM, Zi Wang <ziwang84@xxxxxxxxx> wrote:

I’m thinking if we can work out the transparency of each of the RGB filters
on the CCD and the sensitivity of the CCD itself then we probably could guess
the (or in fact some) reflectance curve(s) by numerical method?

That's exactly what I'm working on right now, but for a camera rather than a
scanner. And using a spectroscope rather than reflective targets.

I can't think of any really good way to do it without a sufficient sampling of
monochromatic inputs, and you're just not going to get anything monochromatic
(or anything even vaguely within shouting distance of monochromatic) from
reflective media.

For a camera, there are three pieces to the puzzle: the per-wavelength
inter-channel ratios; the relative sensitivities of the channels; and the
deviation from linear of the sensor. Put all three of them together and you can
predict the RGB values for any given input spectrum.

Getting those three pieces and putting them together...is the part I'm working
on....

b&

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