It’s not only Pantone that printing lives on

The Pantone system made a name for itself in the trade because it collected and catalogued many colours, extending the range of colours obtainable in print with four-colour process alone and indicating the recipe for obtaining a particular colour in a stable and reproducible manner. Now that Adobe has progressively removed the Pantone libraries from its programmes, are we sure that this is a problem and not, instead, an opportunity?

By Lorenzo Capitani | On PRINTlovers 97

Since last November, since Creative Cloud 2023, Adobe has gradually been removing the Pantone libraries from its programmes, and many in the graphics world, bewildered, have raised voices of dissent. But are we sure that this fact is not an opportunity rather than a problem?

Are we sure that the Pantone system really lives up to its reputation or, instead, that it is being used correctly? Or that what we see printed matter on a swatch actually corresponds to its description? We will try to answer all these questions to shed some light on the complex world of spot colours; with us is Denis Salicetti, Director and TAGA Italia Representative to the Ghent Workgroup and the PDF Association.

The earliest known collection of colours dates back to the Traité des couleurs servant à la peinture à l'eau, a volume of more than 700 pages in 1692 by a Dutch artist known only as A. Boogert1. His idea was to catalogue all tonal changes in watercolours by mixing colours and adding one, two or three parts water; the same idea that came to Lawrence Herbert when he developed the first Pantone Matching System in 1963; 500 hues made up from a set of basic colours. Today, the Formula Guide palette alone contains no fewer than 2390. The Pantone system has made a name for itself in the trade because it has been able to collect and catalogue a large number of colours, extending the range of colours that can be obtained in print with a four-colour process alone, making it possible to reduce the number of inks and, above all, indicating the formula for getting a particular colour in a stable and reproducible manner. The success of the Pantone Library coincided with the explosion of marketing and brand identity in the 1970s and 1980s. Kodak, for example, which produced its unmistakable yellow film canisters from different printers, had the problem that they were not all the same and, according to some market research, consumers tended to leave the darker ones on the shelves, fearing that their photos would not have vivid, bright colours. By using Pantone 1235 for yellow and 2035 for red, Kodak solved the problem.

A big misunderstanding

This was how the Pantone libraries entered graphics and layout programmes, becoming standard in the choice and definition of colour and its reproduction. The Pantone system, however, is only one way of defining a set of colours out of all the millions possible, perhaps the first systematic nomenclature, but not the only one and especially not the most precise. This is fine with the Pantone system itself, but with the use that has been and is being made of it over time, which has generated a series of oversimplifications and ambiguities that make it unreliable. For a start, we have ended up using 'Pantone' and 'spot colour' as synonyms, but they are not the same thing. A Pantone colour is a particular spot colour, i.e. a colour that can be reproduced in print with a single ink instead of a combination of the four basic inks. In other words, I could easily have a spot colour, with its own precise description, which is not contained in the Pantone library at all. "Over the years," Salicetti tells us, "paper Pantone guides have mistakenly become a de facto standard because initially, the system was exclusively analogue; then, thanks to the introduction of increasingly efficient and inexpensive software and measurement tools, we switched to the digital system but left the paper as a purely indicative reference.”

In practice, we took the printed Pantone swatch and its colours as the only reference, believing that the Pantone number was enough to reproduce that same colour in print exactly as seen on the swatch itself. The problem is that it doesn't work like that: the assumption "chosen a spot colour from a Pantone swatch, with its recipe you will get an ink that printed will be the same as the chosen colour" is not correct because the way to define that spot colour and to communicate it is not correct. It is not enough to look at a piece of printed paper and expect that colour to be reproduced exactly like that. There are, in fact, at least two problems.

The first is related to the Pantone swatch because it too is printed and, as such, suffers from all the problems, tolerances and flaws associated with normal offset printing processes (ink density being one of them), undergoes physical alterations due to time, exposure to light, oxidation of the inks and the use made of them, and even if it is of the same series and vintage each copy differs from another.

The second problem is related to the characterisation of the chosen colour, i.e. the reproduction technique and the substrate that will be used in terms of finish, white point and colour: because the same spot colour changes significantly if reproduced on an uncoated paper or a glossy coated paper or even on a recycled board. When creating a brand identity, it is not enough to say the Pantone number, but a precise definition must be given that considers the contexts of use.

Useful but not reliable

There is, however, a further complication that the elimination of Pantone libraries from Adobe's programmes has brought to light, perhaps precisely because this choice has raised the attention of experts: the Pantone swatches are not even that reliable because they change over time, contain typos or errors and the progressive extension of the number of hues has generated paradoxes in the recipes that contain minute quantities of colours that are sometimes indistinguishable to the naked eye. A few examples will suffice. The Pantone 100C of the PMS swatch differs from the one reproduced in the Pantone Plus swatch, as is the Reflex Blue C or the 2635C. The latter, in the 2023 version, has changed its recipe, and to obtain it, it is necessary to mix 95.44% of PANTONE HD Extender (white), 4.15% of Violet v2, 0.35% of Green and 0.06% of Black: ridiculous percentages. Also, in the 2023 swatch, Pantone 114C has the same recipe as 113C, just as 106C has the same as 107C or 108C, the same as 109C. Misprints? Maybe, but theoretically, the ink makers should produce the inks and the printers print on those values. "Theoretically", fortunately, because those who make inks do not rely on the recipe of the swatch but on more certain values to avoid having errors such as Pantones printed on the swatch that, when measured, correspond to others. "Doing some measurements," Salicetti tells us, "we realised that 7541C, for example, measured corresponded to 621 or that 7544C corresponded to 430".

The solidity of digital data

Fine, but if the swatch, as Pantone has been declaring since as far back as 2010 (The 2010 digital characterisation data set is the new de facto reference, not the printed books), is only an indicative paper reference, what unequivocally defines a colour? Its digital data and description in absolute values are scientifically defined according to the Lab (or CIELAB) colour space. In the Lab space, colours are defined according to the values of Brightness, Hue and Chroma: "Let’s imagine that we are in a large room with a pole in the middle: at the bottom, the pole is black, at the top it is white, and in the middle, it has all shades of grey: this is the axis of brightness. As we move around the pole, we encounter all kinds of shades. The further we move away from the pole, the more intense the colours become, defining the chroma. Combining these three elements, we get the scientific description of a colour.”

But where do we find the digital data of each Pantone hue? "In the colour library found in many graphic applications, including Adobe's pre-2023 edition (at iridsystem.it/software/pantone/) there is a tool called Panto-Lab that provides the equivalent Lab values, ed). Each colour correspondence is associated with the respective Lab colourimetric value, determined with precise measurement conditions, generally, D50/2°/M2, carried out with a spectrophotometer.” That's right because it is not enough to indicate the values that define a particular colour (e.g. 70/47/79), but it is also necessary to state how it was measured to reproduce the same measurement conditions and thus correctly evaluate the differences, or tolerances, between a sample and what is actually being printed. D50 indicates the light source, where D stands for daylight and 50 for 5000 Kelvin (light temperature). The second value indicates the viewing angle (2°), while the third indicates the extent to which optical brighteners contained in the paper should be considered: M0, M1 and M2 are present in Pantone's digital data, while Photoshop only uses the M2 value. Now, this can definitely be confusing, but the thing to know in the end is that two spectrophotometers will be aligned if they have the same measurement conditions. So a colour with Lab 70/47/79 values measured at D50/2°/M2 will be reproduced correctly under the same values and conditions.

Measuring, always measuring

The spectrophotometer is an instrument capable of, among other things, measuring two colours and calculating their differences in terms of ∆E₀₀ (read delta E 2000). Now, without going into technicalities, an ∆E₀₀ 1 is the minimum difference perceptible to a colour expert, while typically, a colour difference of around three is perceived. These would seem to be idle matters for colour scientists, yet the impact of using an unreliable reference system such as the printed swatch and not taking measurements can be disruptive. If, for example, the colour we have chosen from our swatch has a ∆E₀₀ 2 compared to the digital data and the printer's, perhaps more used, swatch has a ∆E₀₀ 3, the two swatches could differ by 5, which is a decidedly noticeable difference. Pantone claims that 90% of its printed colours fall within a tolerance of ∆E₀₀ 2, so already 10% is out, and 2 could become 4 by adding up the ∆E₀₀ of two different swatches. What's more: "At the last TAGA Day," says Salicetti, "comparing the digital data of the 2022 and 2023 guides with the respective printed swatches revealed major disparities. For example, in the 2023 guide, as many as 283 colours out of 2134 had ∆E₀₀ 4 (13%), and 84 had ∆E₀₀ 5 (4%)". In short, all members of the supply chain, from the creative to the printer, should have a spectrophotometer because it is "a vital tool for the evaluation of the printed product and because it allows us to obtain an objective, precise, reliable and repeatable measurement over time, eliminating the subjective factor of the observer with the relative psychological component (what Salicetti calls the 'eyepiece meter', ed.) and possible distortions due to environmental lighting conditions.”

Communicating colour

Now that we have a clear reference system and a universal method for measuring colours, we must learn to communicate them correctly, bearing in mind that they will have to be reproduced, not just printed. It is basically a matter of constructing a sheet in which we give the absolute definition of a colour in Lab values, the measurement conditions and the values for each use, from digital to print.

Converting

The correct way to build this card is to start from the Lab values of the colour and convert it into the different colour spaces, starting with RGB, whose profile must also be declared because different profiles have different gamuts, i.e. they have different ranges of reproducible colours: web applications use sRGB, while prepress uses AdobeRGB, which is wider than sRGB and therefore has more colours. Declaring the profile is fundamental because the same RGB values give different colours depending on the profile: Photoshop in hand, the green RGB 86/161/66 is visibly different in sRGB than in AdobeRGB.8 To change a colour from Lab to RGB, it is enough, in Photoshop, with the correct RGB profile set, to start from the Lab sample in Colours and change it to RGB.

The next step is converting to CMYK, which will be used for four-colour printing if you do not want to use a spot colour. The ink manufacturer will make the spot colour from the Lab values defined at the start and measured according to the measurement conditions. When converting to four-colour, there are two approaches: rely on the automatic conversion that minimises the ∆E₀₀ between the starting colour and the CMYK equivalent or optimise the conversion manually. In the first case, you obtain the four-colour values precisely as done for RGB, changing the Lab to CMYK, again with the correct profile (PSO Coated v3 based on FOGRA 51 is currently used for coated paper). In the second case, on the other hand, we convert to CMYK automatically and then intervene on the values to make them more consistent and more printable in terms of quality, stability and reproducibility, according to specific guidelines.

Optimising

Let us take Pantone 362C as an example, which has values Lab 57/-44/43 and CMYK 70/12/99/1. First of all, we must eliminate very low percentages of an ink because they can cause instability during printing and make the colour different not only between different runs but also within the same run: that 1% of black is negligible and can be compensated for by slightly altering the other percentages. It is then necessary to round off the values close to 100%: the 99% yellow in the example, taken to 100%, makes no visual difference and will always be 100% in print. Finally, consider the possibility of reducing the number of inks: an example of how this can be done is Pantone 161C, which automatically converted becomes CMYK 31/61/73/58, but it is possible to obtain the same colour, eliminating cyan, with M 48, Y 62, K 72. 11 This technique is called grey component substitution (GCR): since certain CMY combinations can be considered grey, it is possible to replace them partially or entirely with black. Less colour means fewer plates, less ink, lower costs, greater printability and shorter drying times. Beware, however, of borderline cases. Grey in sRGB 40/40/40, which, when converted to CMYK PSO Coated, has values 67/58/47/78, can be simplified to K 95, i.e. a single, neutral, dark grey ink. In contrast, in automatic conversion, the slightest change in colour in print would result in a grey that is no longer neutral, not to mention that, with those quantities of ink, there could be drying problems. Yet the black alone might not be sufficiently complete. So? "The replacement of the grey component is an operation that can also be carried out on the individual object. This means that the amount of grey component can be increased or decreased depending on the needs of the project, the context of use and the type of substrate: sometimes, it might be necessary to increase the amount of grey component to improve neutrality in CMYK, other times it might be necessary to decrease the amount to be more precise and consistent with expectations. This technique should be used with full awareness to avoid compromising print quality and colour fidelity. When in doubt, asking the printer is always a good idea.”

A stable and reproducible colour

Undoubtedly, these actions could generate a colour that, when printed, does not deviate in the slightest from the starting sample, which, moreover, already happens when switching from RGB to CMYK due to the different colour space: then it is better to adapt the sample itself to obtain a reproducible colour; after all, as daily observation suggests and many experiments have shown, beyond the perceivable minimum ∆E₀₀, the beholder has a memory of the colour that differs from reality (is Coca-Cola red the same as Netflix red? ) and the conditions of observation are constantly changing, influencing perception. How we see a colour changes depending on light conditions, intensity and incidence, other surrounding colours and psychology: just being asked to evaluate a colour makes us hypercritical, which we are not at all in a supermarket.

Having defined the base colour in Lab and the derived colours in the different colour spaces with their relative profiles, it is possible to extend the description to other systems, of which Pantone may be one, but there are others, such as RAL, useful for painting. All that remains is to complete the colour card with some additional, but equally important, information that must be known by those who will have to use the described colour, such as the permissible substrates and finishes. Paper is the so-called “fifth colour” because it has a white point, can be tinted or have optical brighteners that affect the colour rendering and any plasticising or varnishing. To realise the role that paper plays and how solid Lab values are - depending on the declared measurement conditions - we only have to consider that a CMYK 92/0/87/5 green with Lab values on coated paper of 51/-56/22 has a difference ∆E₀₀ 23 compared to the same green printed with the same CMYK values on usomano (Lab 51/-38/7).

From actual to printed colour

Returning to the printed Pantone swatch - which can still be used, but with the understanding that it is a guide to choosing a colour - what is the correct process for creating a colour card that correctly describes what you see on the swatch? For example, if I want to obtain Pantone 113 C as I see it on the coated swatch, whose digital data will give a slightly different colour, how do I get the accurate digital data of what I see? "By measuring with the spectrophotometer, correctly set up, the colour sample we want to reproduce, and obtaining the digital data to compile the colour card. In this way, we obtain an objective measurement of colour, which does not depend on the human eye and the condition of the swatch in use, but is based on detailed and precise spectral information. In addition, using the spectrophotometer makes it possible to obtain digital data that can be easily archived and shared with other parties involved in the production process, thus guaranteeing the reproducibility of the colour over time and consistency between the various production batches.” Yes, because a colour sample, once described, should also be provided as a library to those who have to use it together with the colour card. You start in Illustrator with the colour panel empty ([None] and [Register] cannot be deleted) and setting PSO Coated v3 as the CMYK profile, and create a new spot colour sample with the desired Lab values, then duplicate it and open it up to modify the options with the desired CMYK values for the different paper types, and finally export it as a library to ASE (Adobe Swatch Exchange). This can also be done from Pantone libraries (exported from older versions of the programmes or by subscribing to Pantone Connect), but treated as one of the possible samples and always passing from the corresponding data in Lab.

Produced together with Manuel Trevisan of "Better Brand Color Guide", an international project created to compensate for the elimination of Pantone libraries and to try to resolve misunderstandings between clients and printers on the reproducibility of spot colours.