Continuous tone

(graphic arts) An image which has not been screened and contains unbroken gradient tones from black to white, and may be either in negative or positive form.

A printing process that produces photographic-like output. In a continuous tone image, pixel patterns (individual dots) are either not visible or are barely visible under a magnifying glass. Various dye sublimation and laser technologies can provide up to 256 intensities of color and even blend the inks. See contone printer and dye sublimation printer.

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Image, such as a photograph or painting, comprising all variations of color or shade from black to white and produced by varying concentrations of pigment. For example, watercolor paint can be applied thickly to produce a dark shade or thinly to produce a light shade. line copy however, utilizes the same density of pigment, or ink, throughout the image. Because printers cannot reproduce a continuous tone image, a halftone image must be created from the continuous tone image for printing.

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A continuous tone image is one where each color at any point in the image is reproduced as a single tone, and not as discrete halftones, such as one single color for monochromatic prints, or a combination of halftones for color prints.

The most common continuous tone images are digital photographs. Film is a halftone medium.

An example of a continuous-tone device is a computer screen. Here, any pixel can represent any color, because the color components of the pixel are analog and can vary in infinite steps, and hence do not need halftones to make the colors. Of course a computer cannot provide with infinite tone variations, being a digital device. In 24-bit color mode, it provides the monitor with 256 discrete steps for each color, for a total of 16,777,216 discrete colors. A purely analog video signal (one that has not been manipulated by a computer of any kind) can provide infinite tone variations inside its own gamut.

A halftone device, in contrast, uses discrete dots of color, which at a certain distance look closely like the intended color. Examples of this are inkjet printers. Magazines and most printed material also use this technique to create the colors.

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