Pantone Book vs Pantone+ Book

[Bill W]

With the front end to our digital press I have the Pantone Book and Pantone+ Book in digital form. I noticed that the same color in each book has a different Lab value.

Here is an example of 3 such colors with their Lab values. The first set of Lab values is from the Pantone+ Book and the second set is from the Pantone Book:

103: 70.15, 0.48, 83.65
70.96, -0.92, 87.44

118: 58.13, 9.00, 66.37
59.01, 7.52, 70.56

269: 26.05, 27.08, -30.53
25.66, 23.16, -29.27

When converting to 7 color process these different numbers produce different conversion numbers. While I did not check, I would guess the same difference in conversion numbers would be shown when converting to a 4 color process.

Has anyone noticed these differences? Does anyone know why they would be different?

-Bill-

 

[meddington]

Pantone changes their CIELab values from time to time. I've been told the LAB values are not "official" but provided as a convenience. The ink Formulae are the the only thing that doesn't change from book to book.

 

[Stephen Marsh]

If you measure the Lab values of a Pantone+ swatch book and compare them to the values provided by Pantone in a licensed colour table, they should be “close”. Not every Pantone book is exactly the same, there are +/- tolerance variation.

Moving forward with a new press and setting up your own swatch books, I would go with the Pantone Plus+ value.


Stephen Marsh

 

[Deleted member 16349]

Pantone changes their CIELab values from time to time. I've been told the LAB values are not "official" but provided as a convenience. The ink Formulae are the the only thing that doesn't change from book to book.

Recently I started to realize what I think is the "Achilles Heel" of the Pantone system.

On a different forum, there was a discussion of Pantone consistency etc. Of course the discussion went around the variation of the guides and the use of the guides as standards. One technical person from XRite/Pantone reminded the group that the guides are guides and not standards. OK, that is true but people use them as some kind of standard in practice and this leads to the problem.

I had always wondered why a Lab number was not officially stated for these guide colours. That would be straight forward. I thought it was not done due to variation and maybe due to the situation where if Lab numbers were issued, then why would one need the guides.

So this technician discussed some issues with the guide. One was that designers basically forced Pantone to use paper with a lot of optical brighteners. When I heard this I first wondered how a colour organization that produces guides that are almost standards gets pushed around by the design community to produce a systemic problem in their colour guide system. After that I realized that this was the "Achilles Heel" with their system.

Here is the problem.

If you produce colour guides with transparent inks on paper that has a lot of optical brighteners, then there is no way that one can actually measure the colour of those guides. The Lab number that you measure with an instrument is not so accurate with UV filters or not.

This leads to the question of what is needed to have a colour system as a guide. Well there were some other responses on that group and ones that lead me to some interesting understanding of the problem. What is needed for a standard or guide, is samples that use non transparent ink, even if it is to be used as a guide for transparent inks.

It turned out that there are organizations/companies doing this. One is the NCS colour group.

NCS Colour – Start

I don't know enough about NCS but it is interesting for me to finally understand why Pantone is a problem and that there may be other alternatives that will be more predictable.

 

[Bill W]

I have know for years that the reason Pantone would rather not list LAB values is that the pigments that make up a color do change slightly from year to year. 1 part of this base ink mixed to 2 parts of this base ink is always a good formula regardless of whether or not the base inks shift in hue / chroma. Color may change, but the math is still good :-(

However, do not all desktop application license some kind of LAB value tables to use in converting PMS colors? And are we not kind of slaves to those tables. It seems to me that changing those tables is not very helpful in keeping color consistency.

 

[gordo]

I have know for years that the reason Pantone would rather not list LAB values is that the pigments that make up a color do change slightly from year to year. 1 part of this base ink mixed to 2 parts of this base ink is always a good formula regardless of whether or not the base inks shift in hue / chroma. Color may change, but the math is still good :-(

IMHO, it's called a "Formula Guide" rather than a "Color Guide" because it has formulas for mixing inks. So, as you wrote, in that sense, the hues are independent of the color you see in the swatchbook. Put another way, if your swatchbook is dirty or old and the colors shifted then the formulas will still work to deliver Pantone's color.

However, do not all desktop application license some kind of LAB value tables to use in converting PMS colors? And are we not kind of slaves to those tables. It seems to me that changing those tables is not very helpful in keeping color consistency.

Those are just for convenience to OEM vendors for converting Pantone's library into various output modes (RGB, CMYK, etc.) I don't believe they were ever intended for any other purpose. You could create your own LUT to make your specific output better aligned with the hue you are trying to match.

gordo

 

[gordo]

[SNIP]

I had always wondered why a Lab number was not officially stated for these guide colours. That would be straight forward. I thought it was not done due to variation and maybe due to the situation where if Lab numbers were issued, then why would one need the guides.

The guides are ink formula rather than color guides. INHO, I believe that the formulas are more accurate and repeatable than Lab values would be in a production environment.

So this technician discussed some issues with the guide. One was that designers basically forced Pantone to use paper with a lot of optical brighteners. When I heard this I first wondered how a colour organization that produces guides that are almost standards gets pushed around by the design community to produce a systemic problem in their colour guide system. After that I realized that this was the "Achilles Heel" with their system.

I doubt that is true. The majority of designers haven't got a clue about OBAs. Paper manufacturers have greatly increased the use of OBAs over the years. Pantone probably didn't have much choice.

[snip]Here is the problem.

If you produce colour guides with transparent inks on paper that has a lot of optical brighteners, then there is no way that one can actually measure the colour of those guides. The Lab number that you measure with an instrument is not so accurate with UV filters or not.

I don't know if that's true. Ink offset ink is a pretty good filter of UV light.
Interestingly most offset papers contain OBAs while most proofing papers don't.

This leads to the question of what is needed to have a colour system as a guide. Well there were some other responses on that group and ones that lead me to some interesting understanding of the problem. What is needed for a standard or guide, is samples that use non transparent ink, even if it is to be used as a guide for transparent inks.

My gut says this doesn't make sense.

gordo

 

[Deleted member 16349]

The guides are ink formula rather than color guides. INHO, I believe that the formulas are more accurate and repeatable than Lab values would be in a production environment.



I doubt that is true. The majority of designers haven't got a clue about OBAs. Paper manufacturers have greatly increased the use of OBAs over the years. Pantone probably didn't have much choice.

[snip]Here is the problem.



I don't know if that's true. Ink offset ink is a pretty good filter of UV light.
Interestingly most offset papers contain OBAs while most proofing papers don't.




My gut says this doesn't make sense.

gordo

The call them guides. They are ink formulas based on their inks. Not everyone uses their inks. In production where there is a lot of matching of Pantone colours, one does not follow their formulas.

He said the designers forced them.

That is a surprise. It seems to me that OB have been causing problem with matching printed colours. Are you saying now that it does not. I am confused.

Let your gut think about it longer. Maybe it will change its mind. Ask it later.

 

[rich apollo]

PANTONE Plus replaces PMS. The Lab values for all colors have changed.

 

[Bill W]

Being a flexo printer, we have an HP Indigo that I am working with, we always print PMS colors as spot colors. How does the offset group figure out how to print a spot (PMS) color "accurately" using CMYK? I know the Pantone has a PMS to CMYK guide but if the PMS book is only a "guide", then is not then any book they create only a guide?

I agree with Gordo that could make their own LUT, which is basically what we have done with profile conversions on the HP, but one still needs an input table with Lab values to match to.

I know from experience that my investigation is some what academic as we have been satisfying our customers needs for flexo spot / PMS color for the 29 years or so I have been in this industry and more recently using our Indigo.

I probably never would have been interested in this subject was it not for the Indigo and me noticing some difference in color conversion when we updated the front end to include Pantone+.

The challenge came when I discovered that the values I have carefully placed under all the PMS swatches in a custom book we are printing that shows the difference between printing PMS colors under a 4 color strategy and a 7 color strategy would be different between the "old" Pantone Book and the new Pantone+ book. Some want to use this book for costing and production so the values need to truly reflect what will be printed.

 

[meddington]

With the Indigo front end we had, we had a few options. Let the Rip replace incoming spot colors with Pantone CMYK equivalents, let the Rip convert from Pantone LAB to default Indigo Profile, or create a custom ICC profile and let the Rip convert from Pantone LAB to that. The latter was the most accurate.

 

[akalaray]

With the Indigo front end we had, we had a few options. Let the Rip replace incoming spot colors with Pantone CMYK equivalents, let the Rip convert from Pantone LAB to default Indigo Profile, or create a custom ICC profile and let the Rip convert from Pantone LAB to that. The latter was the most accurate.

Which front end did you have, what version? Do you have something different now?

 

[meddington]

Changed jobs and no longer have access to an Indigo. I can't remember what they called the front end, but I believe it was based on a Harlequin Rip.

 

[gordo]

The call them guides. They are ink formulas based on their inks. Not everyone uses their inks. In production where there is a lot of matching of Pantone colours, one does not follow their formulas.

It's a system - swatchbook, formula, inks, if you change the components then you are no longer in the system.

He said the designers forced them.

Most printers don't understand the impact of OBAs - designers are even further removed. I don't think he is correct.

That is a surprise. It seems to me that OB have been causing problem with matching printed colours. Are you saying now that it does not. I am confused.

The OBAs create problems in two key ways:
1. Proofing papers typically do not contain OBAs while press papers do. That causes an automatic disconnect under different lighting or mixed lighting conditions.
2. Press inks block the effect of the OBAs so, the impact of the effect varies with the tones represented. From 1% to 50% much of the paper is uninked (the space between the halftone dots) so the impact of the OBAs is greater in those tones compared to the tone range between 50% and 100%. The result is that press and proof may align everywhere except in pastel colors.

More info here: The Print Guide: The issues of Optical Brightening Agents in paper and ink

Let your gut think about it longer. Maybe it will change its mind. Ask it later.

Will do. Gordo

 

[gordo]

Being a flexo printer, we have an HP Indigo that I am working with, we always print PMS colors as spot colors. How does the offset group figure out how to print a spot (PMS) color "accurately" using CMYK? I know the Pantone has a PMS to CMYK guide but if the PMS book is only a "guide", then is not then any book they create only a guide?

I agree with Gordo that could make their own LUT, which is basically what we have done with profile conversions on the HP, but one still needs an input table with Lab values to match to.

You have to decide what color you are trying to simulate - the color patch in your swatchbook, the color patch in your customer's swatchbook. an arbitrary Lab value, etc. What some companies do is to print out the Pantone library on their device and make a direct visual comparison of the patches in that printout to the patches in whatever they are trying to match and swap color specifications acordingly. I.e. if PMS 124 in their printout matches PMS 126 in the Pantone book then they change all requests in the file for PMS 126 to PMS 124.
IMHO, you can only simulate a PMS color "accurately" with CMYK if the PMS color was made using process CMYK inks. The spectral difference between the base Pantone inks and 4/C process inks make simulating those spot colors out of process, even if they are within gamut, problematic. Pantone's library was never designed to be used as a way to specify CMYK screen tint builds.

best, gordo

 

[Deleted member 16349]

It's a system - swatchbook, formula, inks, if you change the components then you are no longer in the system.

The OBAs create problems in two key ways:
1. Proofing papers typically do not contain OBAs while press papers do. That causes an automatic disconnect under different lighting or mixed lighting conditions.
2. Press inks block the effect of the OBAs so, the impact of the effect varies with the tones represented. From 1% to 50% much of the paper is uninked (the space between the halftone dots) so the impact of the OBAs is greater in those tones compared to the tone range between 50% and 100%. The result is that press and proof may align everywhere except in pastel colors.

More info here: The Print Guide: The issues of Optical Brightening Agents in paper and ink

It seems that most printers are not working within the system as you define it. That is probably very true but it is also part of the problem I would think.

I looked at the spectral reflection curves for CMY and they all drop off at the low end around 400nm. So this supports your statement that the process inks tend to filter out most of the UV. That was a surprise to me since I thought that was not the case. Then the OB effect with tone makes sense too. Live and learn.

Thanks.

Gordon, just to add another question. The CMY inks might be good filters to UV but what about any Pantone mixed ink? I doubt they all have refection curves that fall down at 400nm area. If they didn't they should be affected by UV getting to the paper.

 

[Bill W]

The knowledge that only so many PMS colors can be accurately express using CMYK is why I have created a book that will have two patches of the same color next to each other. One patch is printed using only CMYK and the other is printed using additional colors (OGV) as the rip dictates. The "additional colors" patch is based on a 7 color profile I built for the press using our paper and varnish.

We use the default Esko front end.

 

[nhprinter]

This may be of interest to all of you. Sorry if it's old news. I've been off the forum for a while.

Major problems with color shifts in any application using the new Pantone Plus Series libraries | Connecting the Dots

Dave