Amplitude modulation. In printing, used to refer to conventional halftone printing techniques in which dots of various sizes (amplitude) are used to reproduce the tones and colors of a continuous tone image, with large dots used to reproduce the darker areas and smaller dots used to reproduce the lighter areas.

Abbreviation for cyan, magenta, yellow and black—the four colors used in most color commercial printing. When printed using transparent inks, the three subtractive primaries—cyan, magenta and yellow—act as individual filters to transmit and absorb light reflected from the surface of the paper to create the colors seen by the eye. Intermediate colors—colors other than the subtractive primaries—are formed by laying one film of ink over another. Black is added to enhance the depth and extend the tonal range of all hues.

A method of preparing images for printing in which the image is electronically scanned, with digital information then used to create a printing plate, without the use of conventional film.

Photographs and those images having a range of shades not made up of dots.

Dot gain is the tendency for all printing dots—halftone, stochastic or hybrid—to grow larger on-press, a part of every printing process. Dot gain occurs at all tonal values, but is most visible in the midtones and in the deep shadows. Dot gain is either real (gains that result from printing processes) or perceived or “optical.” Optical dot gain is the result of an optical illusion; although it is not physically present, its illusion is, and its gain must be considered).

Dots—or lines—per inch, the measure of the size of the dots used in conventional halftone screens, with higher numbers representing finer screens. Most commercial printing today relies on 150- or 175-line screens.

Frequency modulation. Used in printing to refer to stochastic printing techniques in which the number of dots, and sometimes their size as well, is changed to reproduce the different tones and colors in a continuous tone image, with relatively more, closely spaced dots used to reproduce dark areas and relatively fewer, more widely spaced dots used to reproduce light areas. (Compare to AM)

The basis of almost all commercial four-color printing, in which gradations of tone and color are achieved by a system of minuet dots, applied by the printing press.

An area of contrasting lightness or brightness. In printing, the lightest areas of the image.

Methods of printing that combine stochastic and conventional printing techniques to create the illusion of continuous tones. Although the techniques vary, they generally use stochastic techniques in the highlights and shadows and traditional screening elsewhere.

Dots—or lines—per inch, the measure of the size of the dots used in conventional halftone screens, with higher numbers representing finer screens. Most commercial printing today relies on 150- or 175-line screens.

One millionth of a meter. The typical unit of measure for the diameter of stochastic dots.

The tonal value halfway between highlights and shadows.

A distracting, often wavy, pattern that appears in printed images. Subject moirés appear when the image that is reproduced includes grid or line patterns such as those found on fabrics or fences that clash with the pattern of the halftone dots. Screen moirés are caused by misaligned screens or imprecise register.

The correct positioning of an image with regard to the edges of paper and other printing on the same sheet, especially when printing one color on another.

A gridwork of fine lines or dots, opaque and distinct from one another, used to produce halftone images. Halftone screens come in a variety of rulings as measured by the number of crosshair lines per square inch.

The angles at which halftone, duo tones, tri tones, and color separation printing films are placed to reproduce colors.

Having to do with a random variable or variables; involving probability or chance. (From the Greek stochastikos, proceeding by guesswork, ultimately from stochos, aim, guess.)

A family of printing techniques in which continuous tone-like images are reproduced using micro dots of all the same size, with variable spacing between the dots (first-order stochastic printing) or variably-sized dots and variable spacing between the dots (second-order stochastic printing). Identified by a number of trade names, including Staccato®, Diamond™ and others. Also see FM printing