A basic guide (see post #1) to setting up ARGYLL CMS profiling on your computer

nertog

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I checked about 5 times the print setting - I printed with the rel. col. intent - via 2 different programs which create essentially the same output. Prints mentioned above earlier with the abs. col. intent by far don't deliver clean grays.
I'm not looking to small fluctuations - there is a print process on a paper - there is a scan process to create the profile - there is a 2nd print with this profile on the same paper - and I'm scanning this patch sheet 3 x to average it - there is plenty of room for statistical fluctuations.
I would give Argyll a try and use the "Spotread" command to do single measurements of patches. The output is Lab (D50) by default.
 

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My starting point was the same as yours that the abs. col. intent renders grays as much neutral as it is possible , but I got irritated by the actual measurements
printing with the absolute intent and then remeasuring those printed patches should be correct.
and by the above referenced statement that the rel. col. intent prints the exact colors. The actual prints should show evidence for one or the other position.

I'll add measured gray values to the above table with the abs. col. intent printed.
 

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Here is an update with measured values from a patch sheet printed with the same ArgyllCMS profile but with the abs. colorimetric rendering intent, all other parameters are the same - same inks, same paper, same printer and driver settings, same 1 day drying time , measurements with the M2 UV filter and D50. I'm scanning with the i1i0 robot arm averaging 3 scans to reduce read errors, I don't have ArgyllCMS installed.

Netbit Argyll-1.jpg


The a-value stays pretty much the same across all measurements from from black to light gray, the b-value grows to almost -20 - to-19,17 - which is a strrong blue cast and there is nowhere a somewhat neutral gray in the measured values.
 
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nertog

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The a-value stays pretty much the same across all measurements from from black to light gray, the b-value grows to almost -20 - to-19,17 - which is a strrong blue cast and there is nowhere a somewhat neutral gray in the measured values.
Hmmm...something must have gone wrong there. Troubleshooting:

1. The white point should have no ink printed for the relative intent, but there should be something printed when using absolute colorimetric (measurements seem to indicate so). Is this the case?
2. If 1 == true, does the white point look slightly yellowish or do the measurements correspond to the visual impression?
 

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1. The white point should have no ink printed for the relative intent,
Yes, no ink - the measured whitepoint is L a b = 95,10 0,91 -6,53

2. If 1 == true, does the white point look slightly yellowish or do the measurements correspond to the visual impression?
No, the white point looks blueish gray as the values indicate - L a b = 91,33 0,82 -10,95

which is about twice the values of the rel. intent - 0,95 x 0,95 = 0,90 for the luminance and -6,5 x 2 is slightly more than -10,95.

Just imagine a perfect white paper - with L=100 and a and b = 0 , the driver would print exactly the white point value of the paper stored in the profile onto this sheet - exactly the value I measure with the rel col intent and which was used to create the profile for the white point parameter.
 

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