[argyllcms] what am I missing

  • From: prathana shrestha <prarthana_shrestha@xxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Mon, 4 Feb 2013 12:19:59 +0000

Hi

I am trying to calibrate a scanner using Kodak Q60 target.  But I'm not able to 
obtain the LAB values corresponding to the scanner RGB values, as given in the 
'profcheck' file. Please help, what am I doing wrong?Here is the procedure I am 
following: - the correction matrix is generated using: 'colprof.exe -v -am -qu' 
(I expect the matrix value represents XYZ in D50)- the matrix is modified by 
using: Bradford matrix (D50-to-D65) and XYZ-to-sRGB conversion matrix. (to 
apply the correction matrix to scanned RGB values and convert them to sRGB in 
D65)                Bradford matrix =[0.9555766 -0.0230393  0.0631636; 
-0.0282895  1.0099416  0.0210077; 0.0122982 -0.0204830  1.3299098]              
                                                                                
       XYZ-to-sRGB conversion matrix=[ 2.3706743 -0.9000405 
-0.4706338;-0.5138850  1.4253036  0.0885814; 0.0052982 -0.0146949  1.0093968]; 
- the modified matrix is applied to the scanner RGB values to obtain corrected 
sRGB values.
Am I missing something while computing this modified correction matrix?? 
because the LAB values of the patches given by 'profcheck' are slightly 
different  than the corrected sRGB to LAB.
Thanks  in advance.
Best regardsPrarthana
                                          

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