Choosing colors and inks for a publication

Looks like my next Publisher programmability article goes live on MSDN early next week. (Don’t worry, I’ll be sure and let you know what the link is once it gets published.) I’m really happy with this next series of articles, which highlight all the great functionality that went into 2003 to support commercial printing.

This next article is the first of three aimed at showing commercial printers how to use the Publisher object model to automate getting Pub files ready for printing. This one covers color modes, print modes, and how to specify exactly what type of print output you want: separations, composite CYMK, etc.

As I was looking it over, it struck me that the article could probably help anyone who needs to get Publisher files ready to hand off to a commercial printer. However, because the article is aimed at commercial printers, it assumes you already know about color modes, print modes, inks, plates, and all that. So in the selfish interest of widening the audience for my article, here’s a little background on some of the printing concepts touched on in the article.

Specifically: color models, and how they relate to printing. Each color model is a way of thinking about color. In general, there are three color modes you need to be aware of: RGB, CMYK, and spot color.

RGB (Red, Blue, Green)

This is the color mode that is probably most familiar to people. It uses mixtures of these three primary colors to create the full range of colors. As we all know from a certain Pink Floyd album cover, white light splits into distinct types of colored light when refracted through a prism. Specifically, it separates into three primary colors: red, blue, and green. (Yes, we were taught it splits into the Roy G. Biv spectrum in school, but those other colors are actually just mixtures of the primaries.) For this reason, the RGB color mode is sometimes referred to as an additive color mode. The human eye actually contains three types of receptors, each structured to receive one primary color.

Because it is based on the properties of light, the RGB color mode is used by TVs, computer screens, and other display devices. It’s also used by scanners, because they capture an image by scanning it with focused light. RGB is also the standard for most desktop printers-- I’ll explain that later.

RGB colors are expressed by a set of three numbers, one for each color. So your favorite purple might be (102, 51, 204).

CMYK (Cyan, Magenta, Yellow, and uh…Black)

This is the color mode most often used by commercial printers. It is also referred to as process color. This color mode can be thought of as the flipside of RGB, as it is based on the properties of ink, rather than light. When you combine the primary colors of light, you get white light. When you combine the primary colors of ink, you get black (well actually, kind of dark muddy brown, but we’ll get to that later.) Each of the three primary colors here, cyan, magenta, and yellow, is actually what you get when you filter out one of the RGB primary colors from white light. Filter out red, and you get cyan; filter out green, and you get magenta; ditch blue, and you’re left with yellow. For this reason, CMYK is sometimes referred to as a subtractive color mode.

A fourth color, black (K), is added because the three primary inks by themselves don’t produce a crisp, deep enough black for printing purposes. K is used to designate black so as to not be confused with blue (the B in RGB).

The CMYK (or process) color mode is the one used by most commercial print operations. Even if you give your printer a RGB publication, chances are he’ll have to convert it to CMYK before he prints it. So if you know you’re going to have a publication commercially printed, it’s good practice to define it as a CMYK publication from the start.

CMYK colors are expressed by a set of four colors, one for each color. So that same purple would be (85, 81, 0, 1).

Spot color

This is the last major color mode, and it’s also based on the properties of ink. For spot colors, however, each color is printed using a specially-mixed ink, rather than combining inks as in RGB or CMYK. This is kind of like picking a paint color; you’re picking a special ink color from a manufacturer. Pantone has made a business out of defining custom colors like this. So that purple you want might be 16-1248 God Awful Bright Purple.

(Getting Your Geek On side note: When is a color definition system like an operating system? has an interesting take on Pantone’s efforts to expand their color definition standard here:

If you only have one or two colors (and that includes black) in your publication, and you’re getting it commercially printed, you might want to consider using spot color. That way, you end up using (and paying for) less inks. For example, if you have two colors in your publication, if you printed it as a CMYK publication, you’d still have to use four inks. Those four inks would by printed on top of each other on the printing press to create the two colors you wanted. If you set your publication up for spot color, you’d only use two inks: one for each color.

One last note: you can combine CMYK and spot colors in a single publication. In this situation, most of the colors in the publication are blends of the CMYK inks, but one or more special colors that have to be an exact color are spot inks. For example, if you need the colors in your business logo to be absolutely, positively the right shade, and not just the closest approximation that mixing CMYK inks can produce, then consider printing those colors as spot inks.

Now, having read this far, you’re asking: how come RGB is the color mode of choice for desktop printers, when they use ink (or at least toner) rather than light to display color? Here’s the deal:

Desktop printers don’t take CMYK or spot color input. Which isn’t surprising, since most computer applications don’t provide CMYK color information. For example, Publisher is the only Office application, and I believe the only Microsoft app, that has CMYK capability. But all applications need to generate RGB information to even display information on your computer screen anyway. So as long as the printer can accept files with RGB information, then it’ll work.

If you open up your company printer, you’ll find four (or more) toner cartridges. So what gives? Turns out that the printer is actually taking the RGB information you sent in your document, and converting it into CMYK values at the printer. In addition, some photo-quality desktop printers have more than just CMYK toners; some add O (orange) and G (green), or LC (light cyan) and LK (light black, better known as gray) toner cartridges.

Make sense? For information on how to work with color modes in a publication, see the article.

Standard disclaimer: This posting is provided "AS IS" with no warranties, and confers no rights.