Ed #2 > text

Duo, Tri, Quad

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.