[argyllcms] Re: ColorMunki Photo spectral resolution

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sat, 21 Nov 2009 15:29:18 +1100

Keith Winstein wrote:
Wanted to confirm -- does the Munki support the 3.33 nm "high resolution" -H mode in dispread and dispcal?

Yes it does. Of course since I don't have the necessary reference
tiles and reference spectrometers, I can't guarantee the performance
of this mode on either the Munki or i1pro. It seems reasonable, but
use at own risk etc.

Also, I noticed that the choice of 3.33 nm spacing seems to be Argyll's decision and the frequency-space filtering is done in software. Out of curiousity, how well-characterized are the actual raw bands used by the instrument? Is it known what the magnitude response curve of a single raw band looks like?

3.33 seemed to have the best response in terms of narrowing the bandwidth.
In practice it seemed to narrow the effective sample width from
about 20nm to about 10nm measured at half amplitude. I guess 10nm is
the limit imposed by the slit width. The details about the bands
aren't known by me - they aren't documented and one would need
some good laboratory equipment to characterize them. The calibration
is interpolated from the 10nm calibration data in the instrument.
The raw->3.3 nm filter uses lanczos2 which is similar in shape
(although not identical) to the raw->10 nm filters in the instruments
calibration, and satisfy the same constraints (ie. summing to flat etc.)

Graeme Gill.

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