Matching PMS Colors…Part II

Part 1



So that’s all well and good and a nice trip down memory lane old timer, you might be saying. But we live in this world and we gave up printing with potatoes long ago. So what’s the point?

The point is that for each and every PMS color, there is one ideal color value. That’s the color value of that ink printed as its mixing formula on coated stock. For PMS 267C, that comes out to a L*a*b* value of L*27; a*40; b*-56.

Not to get too far into the weeds of color spaces here, but L*a*b* is the colorspace many applications use to make color conversions behind the scenes. While any specific color will have many different values in CMYK or RGB, depending on which RGB or which CMYK–or whether it’s even in a particular RGB or CMYK space–if you can see it, it’s in L*a*b*, and it only has one L*a*b* value.

PMS 267C is L*27; a*40; b*-56. If your customer specs PMS 267C and you print L*27; a*40; b*-56 your customer will love you, because you nailed it. And for each and every PMS color, there’s a similar L*a*b* value that’s the value of its ink formula printed on coated stock that is its actual, ideal, color value.

So what are all the swatch libraries you’ve got in Illustrator?

Well, the ones that contain PMS 267 are all differing definitions of how to get to the same place. Or at least how to attempt to get to the same place.

Here’s how it works: There’s one ink formula for every PMS color, but mix it up and print it and that ink will look different depending on the media on which it’s printed, we’ve got that. But let’s say I work for Pantone and I want to get out a spectrophotometer and go measure that difference. I could measure coated, uncoated and matte. And since they all indeed do reflect light differently, and therefore look different, I will get different L*a*b* values for each one. Cool. Now instead of having one PMS library to sell to Adobe and Corel Draw and Onyx and Caldera and whoever else, I’ve got three…Cha-ching!

That explains the solid, uncoated, and matte libraries. But here’s what I’d ask: Is that how it was originally done? If you were actually using the PMS color, is there a different value (ink) you’d use for coated and uncoated or matte or anything else?

Of course, there are also spot-to-process libraries. What these do is make a conversion for you from the PMS-C ideal for your particular PMS color into some CMYK color space, depending on which one you use.

Well that’s helpful right? After all, I’m printing with CMYK.

Why, yes, indeed you are.

But…and it’s a big but…

These libraries do the conversion for you from the L*a*b* value of your PMS color’s ideal mixing-color-on-coated-stock value to as close as can be gotten to that value in some particular CMYK color space. There are three conversion libraries currently in Illustrator: Process Coated; Process Uncoated; and Process Coated European. And what that means is that depending on which one you choose, the color value you’ll actually be given is the L*a*b* value (defined as a PMS color) that’s as close as can be gotten to whatever particular PMS color you’re after, in that particular color space.

I’m pretty certain Process Coated renders into SWOP; we’ll give it the benefit of the doubt and assume Process Uncoated renders into US Sheetfed Uncoated; and I think Coated European renders into Fogra. (And if those aren’t exactly the ones, they’re close enough for demonstration.)

And here’s the demonstration:

This is a little simplistic, but it’s accurate, and what it shows you and what is true is that there’s probably a lot of print capability that your printer has that isn’t in any of those color spaces. Select one of them, and what you’ve assured yourself of is that you’ll limit the range of colors your printer can hit to the ones that are in that color space.

Bottom line is that sometimes we have a tendency to way overcomplicate things. While digital imaging is numbers on the front end, on the back end it’s still ink on media. And ink on media reacts pretty much as it always has.

For that reason, it makes the most sense to me when printing PMS colors digitally to try and come as close as possible to replicating the process of printing PMS colors traditionally.

Set up right, and with some understanding of the process, it works amazingly well.

To be continued…

Part 3



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