[argyllcms] Re: XYZ and wavelength interval

  • From: Matthieu DUBAIL <matthieu.dubail@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 30 Jun 2010 03:42:26 +0200

Hi Keith,
Thank you for the answer.
I'm still not able to get the same results as Argyll.
Here is how I did the measurement and calculation:
1. Measured with colormunki ang Argyll using -H option for high definition
spectral measurement (from 350nm to 750nm every 3,33nm)

2. Used cubic spline to transform the spectral datas from 380nm to 730nm
every 5nm

3. Picked up the 5nm CIE 2° standart observer.

4 Calculated the XYZ using the following formulas on Excel:
          X = SUMPRODUCT( "CubicSplineTransformedData" ; "StandartObserverx"
) * 5
          Y = SUMPRODUCT( "CubicSplineTransformedData" ; "StandartObservery"
) * 5
          Z = SUMPRODUCT( "CubicSplineTransformedData" ; "StandartObserverZ"
) * 5

I'm getting:
X = 63,5
Y = 67,66
Z = 69,36

While Argyll gives me:
X = 43,37
Y = 46,21
Z = 47,37

What am I doing wrong?

I attached spectral graphic file on how cubic spline perform and standart
observer used (normalise at 555nm).

I fear once I answered this question, I might have a few more on
phototometric (Lux and Guide number calculation) and radiometric (Joule
calcultation) to ask.......

Thank you by advance,

Matthieu DUBAIL

Attachment: datacubicspline.jpg
Description: JPEG image

Attachment: 2deg.jpg
Description: JPEG image

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