Banding

In printing, a press and printing problem of a continuous-flow dampening system used in offset lithography characterized by fine dark and light bands or streaks on the chrome-plated transfer roller which transfer to the plate and, ultimately, to the print. Banding (also called ridging) commonly occurs when a fountain solution containing an alcohol substitute is used with a metering roller possessing a hardness, or durometer, of 25:30 (which is the normal durometer of rollers used with alcohol solutions). Banding is caused by the harder rollers being less water-receptive than softer ones, non-alcohol solutions having a harder time adhering to their surfaces. The solution is to use softer rollers, such those possessing a durometer of 18:22. Some roller manufacturers also produce textured, or grained, rollers which increase the amount of water that can adhere to their surfaces. (See Fountain Solution and Dampening System.)

In imaging, banding refers to a perceptible streakiness of halftone dots, characterized by smooth gradations of dots separated by bands of dots of lighter or darker than desired density, caused by problems in imagesetter film feeding problems, commonly oriented perpendicular to the direction of film travel. (See also Contouring.)

In computer graphics, banding refers to the perceptible "steps" in a computer-generated gradation of color or gray scale.

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