[argyllcms] Re: XYZ and wavelength interval

Dear Matthieu:

 

You should modify CIEXYZ formulas like below:

          X = SUMPRODUCT( "CubicSplineTransformedData" ; "StandartObserverx" ) 
* 5 * .683002
          Y = SUMPRODUCT( "CubicSplineTransformedData" ; "StandartObservery" ) 
* 5 * .683002
          Z = SUMPRODUCT( "CubicSplineTransformedData" ; "StandartObserverZ" ) 
* 5 * .683002

 

The number 683 is connected to the modern (1979) definition of the candela 
<http://en.wikipedia.org/wiki/Candela> , the unit of luminous intensity 
<http://en.wikipedia.org/wiki/Luminous_intensity> . (reference from 
http://en.wikipedia.org/wiki/Luminosity_function)

 

FYI.

 

 

Skyforce Shen

Electronic System Div.
Project Team IV,RSEE4
AU Optronics Corporation
No.23 Li-Hsin Rd.
Hsinchu Science Park
Hsinchu 30078, Taiwan, R.O.C.
Tel: +886-3-500-8800 Ext. 6304 
Fax: +886-3-567-9036
skyforce.Shen@xxxxxxx
AUO.com <http://auo.com/> 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx] On 
Behalf Of Matthieu DUBAIL
Sent: Wednesday, June 30, 2010 9:42 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: XYZ and wavelength interval

 

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
www.presse-bouton.com




JPEG image

Other related posts: