l.a.b. values for Pantone colors

[david m. baker]

Good afternoon:

Per the subject, is there a "calculator" tool out there for converting spot/Pantone colors to their l.a.b. values? I have to find l.a.b. values for the following PMS colors:

5483
417
452
5507

I know you can pick this up in Photoshop, but I also understand the values may shift depending on what your default color space is?

Bottom line what I need to do is create reference data in my spectro in order to capture deltaE variance on these four mission-critical colors. Any suggestions are welcome!

Cheers,
-d-

 

[meddington]

I know you can pick this up in Photoshop, but I also understand the values may shift depending on what your default color space is?

Its not really the Pantone provided Lab values that are shifting, but these Lab values may or may not be achievable depending on the destination color space. As it should be really, as Pantone is first and foremost an ink formulation guide. Different substrates and print conditions using the same ink formulation result in different visual results (i.e different CIELab values).

IMO, creating a CIELab reference for spot colors is usually best done up front with ink drawdowns on the actual substrate provided by the printer and approved by the client.

 

[aricker]

There's a few threads on this subject already, if memory serves, and the consensus was that Photoshop values are probably all you have to go by. Pantone doesn't give digital values easily.

 

[david m. baker]

IMO, creating a CIELab reference for spot colors is usually best done up front with ink drawdowns on the actual substrate provided by the printer and approved by the client.

EXACTLY! Your suggestion is, ultimately, what I've landed on as the best solution. After a little RTFM time, I figured out how you can create a reference based on the ink on substrate (which, thankfully, I have samples of).

Thanks!
-d-

 

[gordo]

I have to find l.a.b. values for the following PMS colors:

5483
417
452
5507

Bottom line what I need to do is create reference data in my spectro in order to capture deltaE variance on these four mission-critical colors. Any suggestions are welcome!

Pantone certified RIPs have Pantone's defined CIE L*a*b* values included to aid in the conversion of spot into process.
Here are Pantone's values for the colors you requested:

PANTONE 5483 C 55.09 -18.65 -11.81
PANTONE 417 C 46.86 -1.9 5.77
PANTONE 452 C 72.12 -2.74 16.72
PANTONE 5507 C 73.7 -5.27 -1.98

Pantone does not provide these Lab values as a target for mixing up their inks, instead they use recipe formulas as per their swatch books. I can't guarantee the Lab values are the most up-to-date since Pantone does change them from time to time and not all RIPs are up to date. But they should give some guidance.

best, gordo

 

[Bondi_dan]

l.a.b. values for Pantone colors

Hi Gordo,

XRite have in fact published Lab values for Pantone colours.

If you have an iPhone get the myPANTONE app.

There you can search for Pantone colours and get their Lab* values.

BTW 5483 C showed up at L* 52.14 a* -17.65 b* -10.82.

This means you and I have a Delta E of 3.27 !

Regards,

Dan

 

[gordo]

BTW 5483 C showed up at L* 52.14 a* -17.65 b* -10.82.

This means you and I have a Delta E of 3.27 !

Regards,

Dan

Thanks for the app info.

As I wrote, Pantone does change their Lab values from time to time so I couldn't promise that the numbers I gave were the latest.

Regarding the Delta E of 3.27. You're using CIE 1976 to calculate the color difference. If I'm not mistaken, the standard for measuring color difference with spot colors is CMC (2:1). That makes the Delta E only 1.57.

best, gordo

 

[Bondi_dan]

l.a.b. values for Pantone colors

Hi Gordo,

Quote:
Regarding the Delta E of 3.27. You're using CIE 1976 to calculate the color difference. If I'm not mistaken, the standard for measuring color difference with spot colors is CMC (2:1). That makes the Delta E only 1.57.
End Quote.

I know the good guys at XRite with the Ink Formulation Software love to use CMC (2:1) because it give the lowest number but Delta E 76 or Delta E (ab) as it is also called is the mainstream in ISO Standards and print buyers in Europe. I see no reason to treat spot colour differently.

In the ISO world there is currently a move towards "Delta E 00".

Regards,

Dan

 

[gordo]

I know the good guys at XRite with the Ink Formulation Software love to use CMC (2:1) because it give the lowest number but Delta E 76 or Delta E (ab) as it is also called is the mainstream in ISO Standards and print buyers in Europe. I see no reason to treat spot colour differently.

Actually, the use of CMC 2:1 for spot colors that I referred to comes from FIRST (Flexographic Image Reproduction Specifications & Tolerances published by the FTA). A lot of spot colors are used in Flexo printing which is perhaps why they write about it in their specifications.

Now I'm probably not up to date, but my copy of ISO 12647-2 does not state anywhere that I could find which formula should be used to calculate Delta E. Nor does my copy of GRACoL 7 which is based on ISO 12647-2. And neither of them talk about tolerancing for spot/line colors. (See latest RErint about standards: http://media.printplanet.com/images/097-Standards-Meeting.png) DeltaEs are mentioned in the documents - but not how they required to be calculated.

So, I think that Delta E 76 might be popular in common usage, but I don't think that it is in the specifications as the required method either for process or spot colors. So, AFAIK, vendors and printers are free to calculate DeltaE anyway they choose (to get the results that they are trying to prove ) One hopes that they say how they're doing the calculation, however, in my experience, this is rarely done. I.e. Vendor could use CMC 2:1 to calculate color difference and states "It's a DeltaE on only 1.5" while the customer is thinking that Delta E 76 was used and as a results says "Fantastic! I'll buy it."

Like I said, I'm probably wrong - so please correct me by quoting from the specifications on how to tolerance process and spot colors.

best, gordo

 

[chevalier]

Graphics - PANTONE PLUS Digital Libraries for Adobe

These free swatch libraries for Adobe software from Pantone are all based on LAB values. They replace the old legacy ones.

 

[Bondi_dan]

RE: Default l.a.b. values for Pantone colors

RE: Default l.a.b. values for Pantone colors

Hi Gordo,

As I mentioned there is no ISO Standard way to evaluate spot colours.

There is some very, very interesting work going on in ISO 17972-4 - Spot Colour Characterisation data (CxF/X4). This Standard is all about communicating spot colour information by specifying how to describe the spectral information of spot colours and carrying that around inside PDF files. More complex than Lab* but much more flexible. In the future software will pull the Lab* value out of the PDF.

Gordo, if you want ISO Standards to be defined outside "Printistan" then you should get involved in your local TC130 Committee It is not as bad as it seems and good people around the world like me are involved.

Although I am a FIRST Implementation Specialist Level II, I do not recall the use of CMC 2:1 - if that is stated as the standard in FIRST 4.0 I will start campaigning against it tomorrow

Delta E 2000 will become the mainstream in the future.

Regards,

Dan