Pantone+ 7433 Solid Coated (Adobe CC wrong Lab values?)

[Magnus]

Hi, Im often getting a request to convert Pantone-colors to RGB, Lab or CMYK.

I usually do the following (In this case I want to convert Pantone+ 7433 Solid Coated to Adobe RGB):

• New blank Lab document i Photoshop
• Choose the right Pantone from the library
• Fill the document with the aintbucket
• Convert to Adobe RGB (Absolute conversion)
• Look at the RGB value in the info panel
• Done!

But today I've noticed something strange.

The Lab value of Pantone+ 7433 Solid Coated in Photoshop is the following:

L 43
a 50
b 2

But when I measure (Spectro M0 D50 2° noPOL) on a couple of different new bought physical Pantone Swatches the color is "much" darker. And I get the value:

L 37
a 48
b 3

So my question is: Can you really rely on the Lab-values from the Pantone+ Color Books in Adobe CC?

Best regards

 

[Stephen Marsh]

Except for a bug or error, the licensed software values should be more consistent than a variable print run. What is the dE tolerance for the solid coated guide?

Kodak = L42.6 a50 b2
CGS = L42.6 a50 b2

Photoshop rounds values to the nearest integer, however that is not the issue.

When I have time I’ll measure our swatch book and let you know.

I think that your question is backward, how much can you trust the print run? The software values are “idealised”, they don’t change, a press does. Yes, a printed swatch book is what you will use in practice… however is your paper stock the same white point as the swatch book?


Stephen Marsh

 

[Stephen Marsh]

Magnus, the difference between your swatch book sample and the Lab software values:

dE76/ab = 6.4
de94 = 6.06
CIE2000 = 5.34
CMC 2:1 = 3.15

dL* = -6
da* = -2
db* = 1


Stephen Marsh

 

[Magnus]

Thanks Stephen, since Kodak and CGS have the same values I trust in the values now. The difference is probably related to the printed swatch book, backing and measure instrument (or all three).

Please measure your printet swatch when you have a spared minute.

Best regards,

 

[Stephen Marsh]

i1 Pro measurements (uncut/no UV filter).

PANTONE PLUS 7433 C = L*41.6 a*50.6 b*2.9

The swatch book is approx. 2 years old and has been kept out of direct light.

____

My swatch book sample compared to the licensed software values from Kodak/CGS:

dE76/ab = 1.47
de94 = 1.13
CIE2000 = 1.03
CMC 2:1 = 0.75

dL* = -1
da* = 0.6
db* = 0.9

____


Stephen Marsh

 

[Magnus]

Thanks for doing this Stephen! Obviously you got a perfect match.
What software are you using to do spot measuring with the i1 Pro 2?

 

[Stephen Marsh]

I’m using an i1 pro (original).

I use the free ColorPort from X-Rite, simply create a single patch test chart (Mac or Windows).

Another low cost option is the new QualityControl from Tucanna (Windows only):

The Color Management Blog: Extend the Functionality of your i1 Pro or i1 Pro2

A demo here:

http://www.printcontrolpro.com/download/QC21.zip


Stephen Marsh

 

[Ferran]

Dear Magnus and Stephen, just for curiosity - and for fun - I have made the same exercise with my Pantone swatch book.
I got this values: L*43.4 a*49.3 b*0.6

Regards,
ferran

 

[Stephen Marsh]

Dear Magnus and Stephen, just for curiosity - and for fun - I have made the same exercise with my Pantone swatch book.
I got this values: L*43.4 a*49.3 b*0.6

Regards,
ferran

Ferran, thanks for joining the party!

Your b* value is unexpectedly off target and near neutral, which leads me to suspect that you have measured using a UV cut/UV filtered instrument, excluding UV (M2). Can you confirm?


Stephen Marsh

 

[Ferran]

Hi Stephen, thank you for this warm welcome
I have realized of that too, so I have used two different instruments (eye-one pro), and surprisingly both gave me very similar values. But no, this two eye-one are without filter (no UV cut). I must admit one of them is quite old (Rev B), and the other one is Rev D.

 

[D Ink Man]

Adding to the fray........

My X-Rite Exact - Calibrated
pAntone pLus Fifth Printing

pANTONE 7433 C

D65-10

L* 39.67
a* 43.13
b* .42

D

 

[benstarr]

My Exact measures

M0 (D50 2°)
L* 40.33
a* 51.54
b* 3.48

It also correctly identified it as Pantone 7433 C in swatch mode with a ∆E 76 of 4.44 (∆L -1.97 ∆a 1.05 ∆b 3.83).

Interestingly the digital values loaded in the exact from the CXF downloaded from xrite gives for the color in M0 are:
L* 42.48
a* 50.53
b* -.35

The M2 (UV Cut) values are:
L* 42.56
a* 50.01
b* 2.01

This leads me to believe that the values published in the digital libraries available in most software are M2 values so if you are measuring with M0 (UV Included) or M1 you are going to get different values from those published in the digital swatch libraries. I haven't really dug into this too much further than this, does Pantone explain anywhere that their digital values are M2?

 

[benstarr]

OK I had to do more digging, it was really bugging me.

I Found this doc on the Pantone digital libraries.

http://www.xrite.com/documents/lite...TONE_Libraries_in_X-Rite_Products_XRGA_en.pdf

I haven't read the whole thing but it contains this very important information: "Most,
 if
 not
 all
 application
 vendors
 utilize
 data
 based
 upon
 UV‐Excluded
 measurements.

"

 

[Stephen Marsh]

OK I had to do more digging, it was really bugging me.

I Found this doc on the Pantone digital libraries.

http://www.xrite.com/documents/lite...TONE_Libraries_in_X-Rite_Products_XRGA_en.pdf

I haven't read the whole thing but it contains this very important information: "Most,
 if
 not
 all
 application
 vendors
 utilize
 data
 based
 upon
 UV‐Excluded
 measurements.

“

Thanks benstarr, it is now bugging me too.

I presumed that UV included would have been the case, as this is what one would use for measurements of Fogra39 or GRACoL C1 specifications, however the white paper does say that the digital reference values were created with UV excluded.

What bugs me is that my Rev D uncut i1 Pro is close to the UVcut values for the colour in question, however perhaps it is opaque enough that the underlying OBA content of the paper is not an issue. I may have to repeat the exercise with a more transparent ink and compare.


Stephen Marsh

 

[rich apollo]

The Pantone values in the Pantone color manager are M2. I believe, but cannot absolutely confirm, yet, that the libraries licensed by Adobe are also M2.

 

[dabob]

Just happened to see this after reading this thread . . . another take on color . ..

Is Your Red The Same As My Red? | IFLScience

 

[Magnus]

Thanks for clarify this. Did not know that the Pantone Lab-values are M2-values. Good to know for the future.

Best regards /

 

[benstarr]

One other thing I forgot to throw in there is the Pantone books can vary. I was involved with some testing a long time ago where we measured several colors and compared the values of different Pantone books and the ∆E variation was pretty high; book to book some colors had variations above 5 ∆E.

So there is always print variation to consider when measuring the books.

 

[D Ink Man]

One other thing I forgot to throw in there is the Pantone books can vary. I was involved with some testing a long time ago where we measured several colors and compared the values of different Pantone books and the ∆E variation was pretty high; book to book some colors had variations above 5 ∆E.

So there is always print variation to consider when measuring the books.

benstarr,

Funny that you mention that. Have a peak.

http://printplanet.com/forums/ink-s...-discussion/19272-p-n-t-o-n-e-thoughts-9-11-a

D Ink Man

 

[Stephen Marsh]

Pantone states that the printed books are a guide (with expected variation), while the digital values are a reference (absolute).


Stephen Marsh