Ed #2 Quadtones

A magician makes an elephant disappear.

The desert oasis is just a mirage.

Somebody tells you, “Love that outfit.”

Things aren’t always what they seem.

Even when you see them in black and white.

Today, graphic designers are putting more color into black and white images than ever before. Aided by desktop print production tools, such as Adobe^® Photoshop^® and Illustrator^®,  and the near-universal availability of four-color presses, designers are adding colors to enrich, improve and add to the impact of conventional black and white images.

The questions are “How?”, “When?” and “What?” How do colorful black and white images work? When should you use them? And what goes into using them effectively?

To answer those questions, we first need to recap how halftones work. That’s because the vast majority of the commercially printed images that appear today are halftone images, very like the first one that appeared in 1880.

Halftone images begin with the fact that most presses use an on-off principle. They either apply or withhold ink, with no middle steps. To recreate the continuous tones that are seen by the human eye, the image to be printed is separated by a screen into countless tiny dots that are blended by the eye to create an illusion of continuous tone, even though the press still only applies or withholds ink.

In a conventional black and white or one-color image, the white or light gray images are formed by tiny black dots separated by considerable white space—the unprinted surface of the paper. Darker tones, or shadow areas, are made with larger black dots separated by less white space.

So if you are using a four color press, why not just print a four-color (or in this context, full-color) image? In many cases, such as historical or editorial photos, a four-color image simply isn’t available. In other cases, the designer or client is aiming to create a specific mood or look. The producers of a company’s annual report, for example, may want to create an image of cost-conscious austerity, without looking boring or unsophisticated. Advertisers may feel that high impact “black and white” presents the elegant image that their product or message needs.

There are other reasons to use black and white quadtones too. Color adds emotion and meaning, even when it is used subtly, say to warm up a portrait. Images printed in four-color black and white also can have a depth that is almost sculptural, because each color that is applied can help to expand the tonal range of the image. Specific features of the photo, including highlights and shadows can be emphasized to a greater degree than in the original. Quadtones can also be used to create special effects, such as an antique look, and help add punch to so-so images.

Once you decide to go with quadtones, how should you use them? Often, the colors are used to highlight certain areas of the image. An application of cyan, magenta and yellow under the back ink, for example, can serve to intensify the shadow areas of the image. Using magenta on midtone areas could help add extra warmth to a portrait, while using cyan in highlights and midtones will give the image a cooler feel.

The choices are virtually unlimited–practically anything is possible. But just because you can do something doesn’t mean you should. In the wrong hands, quadtones can be garish, muddy or distracting. As always, your approach should reflect the goals of the project, the needs and expectations of its audience and the desires of the client.

The fun begins when a black and white image is printed on a press equipped to reproduce multiple colors. Instead of employing a single halftone screen, two or more halftone screens are made from the same image. Two or more plates are then made and two or more inks are used when the image is printed.

Duotones, as the word suggests, are made from two halftones of the same image. The first screen prints the black ink, just as in a conventional one-color image. The second screen applies another layer of black or color, often only to a smaller range of middletones, to create a greater range of tones and add more depth to the image.

Tritones use three inks and three screens to create an even wider range of highlights, middletones and shadows.

Quadtones, a.k.a. “quadratones” and “4-color black and white”, use a full four-color printing press, with four screens, four inks and four printing plates to produce a “black and white” image of incredible richness and depth.

Because they are the ultimate expression of colorful black and white, we have made quadtones the center of this issue of Ed. “But what’s the difference,” you might ask, “between a quadtone and traditional four-color printing?” It’s a good question, and the answer can vary. In fact, some reference works use the term “quadtone” to refer to any four-color printing. Others, use “quadtone” to refer to an image that is printed using four different tones and densities of blacks.

For our purposes, a quadtone is an image that either begins life as or is converted to a black and white, or grayscale, image, which is then printed using the four process colors of cyan, magenta, yellow and black—CMYK.

Such images can be printed in one pass on a conventional four-color press, and, if desired, appear alongside conventional full-color images. In other words, we’re talking about practical quadtones, that are relatively simple to use and that have the widest application.

While it’s easy to create an interesting, great looking image on screen, remember, it’s the printed color that counts. Unfortunately, the way monitors display color and the way color is printed by a press are very different, so what you see on screen may not be what you get on press. The resolution of the image on press—the fineness of the screen that is used—and the brightness and surface of the paper have a big impact on the appearance of the printed image too.

There are other issues as well, including the distracting moiré patterns caused by improperly aligned halftone screens. You can’t see them on your monitor, but they can cause big problems on press, which is why you may find yourself wishing that two moirés never come.

To help manage these concerns, you need to work with your printer. You should sit down together and review the artwork that you are supplying. You also need to get an accurate color proof. The most accurate color proofs are made from the film that will be used to make the printing plate, but they are not an option if you are printing the project digitally, skipping film and going straight to plate. In that case the best bet is to ask for a digital match print, which shows the dots as they will be printed on the plate, along with any moiré patterns or other potential problems with the screens. Another alternative—dye sublimation proofs—are an acceptable, but not great, choice. While they show the halftone dots, they cannot provide advanced warning of moirés or other problems.

Laser proofs can be misleading, because laser printers only produce 2,000 colors, far fewer than the 24,000 colors that can be achieved with a printing press, and the colors they do produce are often oversaturated.

Most printers will tell you that investing in a good proof is money well spent, because it will help you avoid even more expensive problems later on. But remember, even the best proofing process is just a simulation and does not apply printing ink to the paper that will run on the press.

Like just about all four-color images, quadtones look best on coated paper. That’s because the hard, relatively nonporous surface of coated paper holds each halftone dot precisely, without allowing it to run into other dots or be absorbed into the capillaries of the paper. This superior dot holdout—and reduced dot gain—means that each layer of ink can precisely filter the light that strikes the surface of the paper and reflect back clean, unmuddied colors and tones. And we’re not just saying that because we make the world’s finest coated paper. It’s the law—of physics.

You can find the right kind of coated paper for practically every project, and different coated paper finishes help you achieve different things. Gloss allows you to print highly reflective art, such as photography, with the greatest possible clarity and sharpness of detail. Dull combines lower light reflection with better readability and uniform print smoothness. Our glare-free, easy-to-read, matte has a rich, tactile quality as well as increased bulk, to help add more substance to the project.