[argyllcms] spec2cie

  • From: Joe Tschudi <tresorjoe@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 4 Sep 2013 15:06:45 +0200


I am getting weird results out of spec2cie when converting spectral data to CIE 
data by using a custom illuminant. First I tried spotread (spotread -v -s  -c1 
-a CustomTest_spotread.sp) to get ambient emission curves to be saved as an .sp 
file. I also tried illumread (illumread -v -c1 CustomTest_illumread.sp) but the 
results after converting with spec2cie are even further off.
I have spectral remission data that I measured using the same device (i1Pro 2) 
with chartread (chartread -v -c1 -p -L -S TEST) which I am trying to convert 
from spectral data to LAB using the custom illuminant with spec2cie -v -n -i 
CustomTest_xxx.sp spectral.ti3 cie.ti3

Although the CCT of the emission curves shows me a value of around 5850K I am 
getting LAB results that are completely blueish and have nothing to do anymore 
with the original spectral color. To compare the results I am using Bruce 
Lindbloom's Spectral Calculator Spreadsheets (10nm) 
(http://www.brucelindbloom.com -> Calc -> Spectral Calculator Spreadsheets -> 
scroll down for 10nm Download) where it's possible to fill one custom spectral 
(remission) column and a custom (emission) illuminant and the results there are 
correct IMHO.

Using regular spec2cie with -i D50 I get:
2° LAB 91.21 / 0.15 / 4.34 

With the Spreadsheet I get:
2° CustomIlluminant_spotread: LAB  91.12 / -0.47 / 4.49
2° CustomIlluminant_illumread: LAB  91.04 / -1.12 / 4.50

With spec2cie I get:
2° CustomIlluminant_spotread: LAB 91.12 / -4.29 / -4.91
2° CustomIlluminant_illumread: LAB 91.04 / -12.35 / -20.10

Am I doing something wrong?

Attached I am sending the TEST.ti3 spectral remission data, both 
CustomIlluminant_spotread/illumread.sp and the Spreadsheet of Bruce Lindbloom 
to fill the r/emission data.

Thanks for your help in advance if you can provide any.

Best regards,
Joe Tschudi


Attachment: TEST.ti3
Description: Binary data

Attachment: CustomTest_illumread.sp
Description: Binary data

Attachment: CustomTest_spotread.sp
Description: Binary data

Attachment: SpectralCalculator10nm.xls
Description: Binary data

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