Matching PMS Colors…Part III



Part 1
Part 2

To summarize so far: In the spot color world, you’ve got one formula of ink that is a particular PMS color. Regardless of the media involved, you use that formula of ink when you’re printing that PMS color. Also, that PMS color has an ultimate L*a*b* value: The L*a*b* value of that formula of ink printed on coated stock. Whatever stock you print it on other than coated, even though it’s the same ink, you’ll get a different L*a*b* value, but it is still that PMS color.

You don’t have to go through any formulas or machinations to get to that L*a*b* value either. You just ink up the press, print, and there it is. You can measure it if you want, but it really doesn’t matter. Provided you mixed the ink correctly and printed it correctly, whatever it is, it’s that PMS color on that stock.

There’s a conception out there that in the spot color printing world, that’s pretty easy; that there’s just coated and uncoated and matte, and that’s pretty much that. It’s thought that things are much more chaotic in the large-format digital world, what with this vinyl and that backlit and the other artists’ canvas.

However, it should be noted that while all that may be true, it’s also true that if you were going to take any of these same materials and print them –say– silkscreen, and print your PMS color as a spot, you’d still mix your PMS color by its formula, and you’d get what you get when it prints, differing and unique L*a*b* value and all, and what you get would be accepted by all as that PMS color on that material.

So that’s all well and good but it has nothing to do with digital, right? After all, the whole issue is that the ink formula is a constant whereas a digital equivalent of that formula is not, right?

Actually, wrong. The constant is the L*a*b* value of the ink formula printed on coated stock. And that value is unchanging. The goal in all cases is to get as close as possible to that value. The difference between spot and digital is really just the tools you use to try to get there.

Of course there are all sort and manner of work-arounds to help you print PMS colors in the digital world. Surely you’ve had salesmen pitch them at you:

Buy my this or my that and I’ll help you figure out what to do when a client calls for a PMS color…

Buy my KATZpaw and it’ll print you a chart that you can give to your client or read into Photoshop, then go over here to this table and enter this L*a*b* value and…

No, no…You don’ need no steenking PMS colors. Just print a swatch chart on every single media you ever use, on every single machine in your shop. Then –“It really is just that easy!”– you just get your PMS book, find the closest matching swatch to the color your customer wanted, then you write down that CMYK number and go enter it into your design application and…that’s all there is to it!


But you might stop and wonder: What is it that these and all the other work-arounds have in common? Just what is it that they’re working around?

What they’re all working around is the degree to which you don’t really know exactly how your printer prints.

In spot color printing, you take a known quantity, the ink formula, and you use it to reproduce your color in any situation, and you’re confident of the result, because you know what your printer’s going to print. It’s going to print that ink.

Well, if –if– you understand exactly how your digital printer prints, you can always do the digital equivalent of the same thing.

If, in any printing situation, you’ve got your PMS color and its ideal L*a*b* value, and your goal is to get as close as possible to that L*a*b* value on the media on which you’re printing and with the device and techniques you have at your disposal, then the question becomes: In digital, how do you get there?

Well, you’ve got all these pre-packaged libraries in your applications and you could use one of them as a starting point. But keep in mind that what they all have in common is that none of them relate exactly to your digital printer printing on the media you’re using. Another thing they have in common is that they were all created by converting the ideal L*a*b* value of the very same PMS color you’re attempting to match into whatever color space they happen to be.

Note that that’s exactly how they were all created, too. No one from Pantone really printed all their colors on those various media and read them with a spectrophotometer to get all those libraries. They simply rendered each color into each of those color spaces. And if you have a RIP, and that RIP has in it a PMS library, then what you have at your disposal is the tools to do the very same thing.

Provided you’re absolutely confident that when it comes time to render your color into the final color space–your printer’s profile–that that color space is what you printer actually prints.

When printing with a solid PMS color, you can print on any kind of stock and you can be confident that you’re going to get as close as possible to the ideal L*a*b* value of that PMS color printed on coated stock as it’s physically possible to get given your printing conditions simply because of the fact that there’s only one formula of ink that you can use. Use it, and the media and the ink do the work of defining that PMS color on the media you’re actually printing, because they have no choice.

And you can do the exact same thing in digital. The key is to start with a color’s ultimate L*a*b* value (the PMS C color), and to be absolutely confident of the destination color space (your printer profile on a given media.)

Let’s say you’re attempting to hit a PMS color using an Oce 550GT printing on Sintra. There’s some L*a*b* value that that machine printing in its ideal state printing on that media can produce that is as close as it can possibly get to the ideal L*a*b* value of any particular PMS color. It may actually be able to hit the L*a*b* value of a particular PMS color exactly, in which case that L*a*b* value and the PMS formula color will be an exact visual match, or it may be off by some degree. If it’s off, then the goal is to get as close as possible to the ideal L*a*b* value in the color space of that printer on that particular media.

And again, that’s exactly the way every one of those libraries tucked into Illustrator does it. They have a known color value, and a known destination color space. They render each color into the destination space and furnish you with the result. And everyone who buys color accepts those results as those PMS colors.

As an example, going back to PMS 267, it’s ideal L*a*b* value is L*27; a*40; b*-56.

How do we find out how close to that we can get printing on Sintra with the Oce?

First off, what if we say we’re not printing a spot color so we need to convert to some other PMS library first?

Okay. Sintra’s kind of a matte-looking material, but it’s got a pretty hard surface. There’s not a matte conversion library, so is Sintra closer to coated or uncoated? Coated, most likely.

Alright, that means if we use the solid to process library we’re going to get conversions to corresponding L*a*b* values based on the color gamut of SWOP.

So, here’s a comparison of PMS 267C; its L*a*b* value rendered into SWOP; and also rendered into the color space of an Oce 550 printing on Sintra.

What this shows is that PMS 267C falls somewhat outside the gamut of the Oce on this material, and even further outside the gamut of SWOP. But which is closer to the ideal? Both by the path and by the L*a*b* values, you can see that while the Oce doesn’t quite get to 267C, it comes pretty close. And, further, there’s no use wishing or arguing or complaining or even going any further. This is the digital equivalent of printing PMS 267 ink on this particular substrate. It’s the closest possible match there is.

Obviously any client wanting PMS 267 on coated stock is going to be a lot happier with the color rendered directly to the printer’s color space than to SWOP.

(Although note that if SWOP is the goal it’s easy enough to do. That would be an occasion –the only occasion in my view– to render to Coated–to–Process and then to the printer space. Note too that in most cases, large-format printers pretty much cover the entire gamut of SWOP, so if you do go that route, if your printer profiles are dead-on accurate, you will achieve an exact match on almost every color. The degree to which you’re off in that case is always how far off your printer profiles are from what your printer actually prints.)

So what’s the key?

The key is absolutely rock-solid, dead-on printer profiles. What makes this process work in all cases, whether conversions to colors in libraries created by Pantone or into individual printer color profiles, is that the destination color spaces have to be absolutely accurate.

And when it falls apart, this is where it falls apart, and it’s also the issue that all work-arounds work around.

All of them.

How so?

Well, if your printer profiles are absolutely dead on and correct, then when your RIP renders a color into the colorspace of your printer via its profile, then obviously that color is going to be the color your printer actually prints. If they’re not, then just as obviously, it won’t be.

If your printer profiles match precisely what your printer actually prints, then there’s nothing to work around. You can hit as close as your printer can possibly get to any PMS color on any media on the very first try. And once you’ve got that capability and once you’ve got the confidence of that capability, there won’t be any need to waste time, money and material chasing a better alternative. You’ll already be there. And once you have that capability and that confidence, you’ll be able to relate both to your clients, and they’ll quickly learn to trust your abilities and your expertise.

Okay, then. What’s the catch? And if it’s so easy, why does everyone say it’s so hard?

Well, the catch is that while the concept is actually pretty easy, the execution is another story. And it’s something of an irony in this industry that you have any number of people who have things to sell you who often don’t really understand the nature of the processes involved in producing what you have to sell using the things they sold you. You also have people with things to sell who are just loathe to tell you anything other than that getting great color using their–whatever they’re selling–is just super quick, and super easy.

Which it is, up to a point. But if you’re critical about color, that point’s not going to be good enough. The fact is that what all of the above boils down to is that every time you print, you need to have full control of your printer to achieve maximum results. In digital printing, that means spot on media profiles for every single printing condition you use.

Digital printing really isn’t all that different from traditional printing, and the fact is that however the ink gets to the media, once it’s there all the old rules still apply.

You can match PMS colors in very much the same manner with your digital press as has been done with spot colors –if– you are in complete control of how your printer prints.

Because here’s the bottom line: With every machine you have, and on every media on which you print, for every PMS color you need to match, there’s a certain color you can print that’s as close as you’re going to get. Obviously for each color that’s going to be different, as well as for each machine and each media. Just exactly as is the case when you’re printing a spot color on differing types of media.

The question then is: How do you most efficiently go about finding that closest match color? And the answer is, you can hunt for it using any number of workarounds, from just printing swatch after swatch till you get there to using a helper app to printing up swatches in advance…or you can do exactly what Pantone does, know your ultimate starting point color, and know each color space you’re rendering into precisely enough so that you’re confident of your result on the first try.

And that means having absolutely rock-solid accurate printer profiles for every situation in which you print. Have them, and you’ll get the best possible match on the first try with every PMS color you’re attempting to match. Don’t have them, and at least be aware that in all cases what it is you’re chasing in your work-around, whatever that work-around is, is the difference between the profile you’re using, and how it is that your printer actually prints.



One Response to “Matching PMS Colors…Part III”

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