Spot, CMYK, RGB colors explained briefly

This article is a bit wordy…so buckle-up!

CMYK, RGB, and PMS/Spot all have their places. Web designers will almost always be concerned with RGB because almost all of their work deals with things that are viewed on screen (from a monitor that uses Red, Green and Blue pixels, RGB). Print designers have an obsession with CMYK (Cyan, Magenta, Yellow and blacK) because their work deals with things printed by printers that add ink to pages. And some designers even use spot colors! Spot colors allow exact color matches across all printable mediums and allow for special processes that a designer can only achieve using “spot colors.”

RGB Colors

RGB. Red. Blue. Green. Pixels on your screen are made up of these colors and use a subtractive color theory [link]. There is a bright light behind those colored squares and it shines through small crystals (LCDs anyway) and reduces certain lightwaves to produce the colors that you see. Why is this important to know? Web designers do not worry so much about color because every computer monitor will have a slightly different gamut and give colors a different appearance.

Still want to know more about RGB? Check this out

CMYK Colors

Cyan. Magenta. Yellow. blacK. The only logical reason that I can see it’s not abbreviated as CMYB is because the B might be confused with the color Blue, but it’s just a guess (don’t quote me!). CMYK are the ink colors that are applied to paper using an additive theory [link]. The mixture of the four colors produces a wide array of colors (aka. gamut) but is limited to brightness (or lightness) of the printed material. For example, printing a full color image on a tan paper will drastically reduce the tonal range that you can see making the image appear muddy. To avoid this, use a material that is light enough to make the range of colors most visible.

With many of today’s built in raster-image-processors (or RIP, the part of the printer that processes what you sent to it into little ink dots or lines) printers can achieve a much greater range of colors than in the past. Most people are not aware the steps a computer and printer takes to get from on screen to on paper. First, artwork that you made on the computer (let’s say Illustrator using a combination of vector and placed bitmaps) is sent to the image processor for your personal printer in a format that the printer can understand (Postscript, PS, or PCL, Printer Command Language, or raster image). This coded language secretly describes to your printer how it should lay down the four inks in it that you paid a pretty penny for. It makes four color separations, one for each of the CMYK. Through a combination of densities and proximities of thousands of small dots (for inkjet printers) or lines (for laser printers) your artwork is reproduced as close as it can to what you see on screen. Printed materials using a CMYK system have a difficult time reproducing many dark blues, oranges, and vibrant colors such as pastels and flourescents. But next we read about how designers can sometimes work around these limitations.

Still want to know more about CMYK? Check this out

Spot/PMS Color

Experienced and well-rounded designers know the importance of using Spot colors. Spot colors are used to specify a certain color, ink or coating for a design project. Try to tell your favorite local printer that you want the yellow in your design to be printed in metallic gold and watch them laugh at you. Spot colors open a whole new realm of creativity and classy design. Spot colors and separations tell your printer (whether it be offset, screen print or otherwise) that everything that is a particular spot color will be a certain material/ink. The fun comes in when deciding to use a spot UV coat (a glossy area or image that covers only certain parts), metallic ink, white ink (since there is no white in CMYK, this gets tricky) or any special coating.

Spot colors are are most commonly used for color matching. You have probably heard of “PMS” colors before, but maybe you don’t know what it really entails. PMS is the most common color matching system. It stands for Pantone-color Matching System. When a color needs to look the same, no matter what it’s being printed on or who it’s being printed by, use spot colors. Hopefully you have seen the Pantone books around [insert photo]. These are color sample books and you should have a recent set if you are serious about what you do (or at least, the color of what you do). Ebay for Pantone Swatch Books and try to find a deal. Let’s face it, you’ve sat in your room or at the school lab tweaking each of your colors till they look just the way you want them for that “big project”. But now it’s time to print them because the client your working for just gave you the go ahead. You’re not seriously going to print all of them on your home printer are you? And chances are, you’re not going to have the opportunity to hang over the presspersons shoulder and ask him to add a “bit more” of this color or “lighten” that up…so let’s learn to use spot colors.

Another important thing to remember is to use Spot colors to save money on printing. Spot colors are actual inks that are put on the press and laid on the paper. If you’re going to use a blue and black color, why use full color printing, CMYK? Not only can you specify the EXACT blue you want if you specify PMSs, but you can print on a wider range of papers and weights. And often times at a much higher line rate (oh you inkjet people will know this as “dpi” or dots per inch) at a much, much cheaper price. Know those fancy paper swatch books you’ve seen around, or some well-designed pamphlet that really caught your eye, chances are the designer took the time to strategically design it with the final product in mind. By wrapping your head around the use of Spots you can turn heads and find ways that separate your work from the masses.

Another thing to consider is that some printing processes require “spot” colors. Screen printing on shirts is just one example. There are ways to print directly on garments (called Direct-to-Garment printers that work more like an inkjet printer). Most lithographic, letterpress and flexographic printers require plates as well. In an upcoming article I’ll dip into the world of printing and explain the different processes that are used to create certain effects and print on difficult materials (like chip bags, plastic bags, thick papers, plastic, raised inks…)

Can You Achieve PMS colors in CMYK or RGB?

Sure, well you can get close at least, using tools like LINK. This nifty tool gives you a percentage of accuracy.
But if you have Pantone or PMS swatch books they often include little marks next to the name of the color that tell you whether or not that specific color is achievable using CMYK.

But by no means is CMYK ever a true substitute for PMS colors. PMS colors use a combination of inks specifically and meticulously mixed for color accuracy. For example, Pantone 394U (U=uncoated paper), is a precise blend of 8 Parts PANTONE Yellow, 1/8 Part PANTONE Green, and 12 Parts PANTONE Transparent White.

Can You Achieve a Gold color in CMYK?

You certainly can get a “goldish” looking color without the luster and shine of using a true metallic ink. I’d suggest using a blend close to the colors listed below in a gradient with similar colors for a more natural look. To make it look more realistic, add a texture or subtle bump map.

Metallic Gold:
C = 42
M = 43
Y = 72
K = 17

Golden Yellow:
C = 18
M = 31
Y = 97
K = 3

UPDATE!

Answers to your questions, short and simple

How can I lighten a colour for print but still have just one PMS color?

Screening or lightening a Spot color is actually referred to as “tinting”. It is not the same as opacity. “Lightening” or tinting a spot color is done by created by varying the density of dots of the solid color. In InDesign, the tint is a slider in the swatch panel.

Is it possible to blend PMS colors with CMYK?
Yes. Through a very carefully calibrated printer (which I won’t go into detail in this article) you can print full color images and graphics and still retain PMS colors in calibration. Often times this sort of printing is very expensive and found only at high end print shops or graphic enthusiasts. Or you could have a 4 color print, then print the PMS ink over (with some considerations).

Can you use a metallic spot color in a gradient?
Yes! Used like any other spot color, you can create illusions of gradients by dot/line placement. Get creative!

Any questions?

In the meantime, if you have any specific questions or concerns about color spaces…don’t be bashful, you’re probably not the only one!

3 Comments

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