[argyllcms] eye-one pro Rev A/Rev D IR calibration?

  • From: Klaus Karcher <lists@xxxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sat, 26 Jun 2010 00:22:36 +0200

Hi all,

I noticed some weird differences between an eye-one Pro rev. A and my rather new rev. D: the reflectance measurements in last few bands (approx 743 ... 750nm) are significantly lower with the rev. D than with the rev. A. Furthermore the results for this bands seem to be more temperature-sensitive.

I have few possibilities of comparison, but there is some evidence that the rev. A results at the red end are more reliable than those of the rev. D (e.g. polystyrene spectra measured with the rev. A end in a vertical line with, but drop down when measured with the rev. D).

Here some files:

500-patch-target, strip lenght: 25 patches, laserprint on FWA-free paper, measured with eye-one Pro Rev A in high spectral resolution mode

same print, measured with rev. D

reflectances rev D divided by reflectances rev A, mean and median of all patches ploted against wavelength.

reflectances rev D divided by reflectances rev A, mean of 3 bands,
(443...450 and 743...750nm) ploted against patch index.

Even though in general the repeatability the rev. D seems to be much better than the rev. A, there seems to be an issue in terms of IR calibration.

The (differences in) thermal drift of the instruments obviously affects mainly the measurement results at the red end of the spectrum.

At first sight it's unclear which of both instruments is stronger affected by thermal drift (I dare say the radiation maximum of the lamp is still above the relevant wavelengths at the end of the reading, but I have no idea which compensation mechanism might affect the result).

I guess the issue has practically no influence on the Lab values as the spectral sensitivity of the standard observer is close to zero in this region, but I need reliable data also in this region. Any ideas how to improve the IR results of my Rev D?

Thank you!

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