halftone

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halftone

Art a tonal value midway between highlight and dark shading

halftone

[′haf‚tōn]
(graphic arts)
An engraving used in printing to reproduce photographs and drawings that contain continuous tones, that is, grays (middle tones or halftones) in addition to black and white; preparation involves photographing the artwork through a screen.

halftone

(graphics)
The reproducion of greyscale images using dots of a single shade but varying size to simulate the different shades of grey.

Laser printers that cannot print different sized dots, halftones are produced by varying the numbers of dots in a given area.

This process is also used to produce a black and white version of a colour original using shades of grey in place of colours.

See also device independent bitmap.

halftone

In printing, the simulation of a continuous-tone image (shaded drawing, photograph) with dots. All printing processes, except for Cycolor, print dots. In photographically generated halftones, a camera shoots the image through a halftone screen, creating smaller dots for lighter areas and larger dots for darker areas. Digitally composed printing prints only one size of dot.

In order to simulate variable-sized halftone dots in computer printers, dithering is used, which creates clusters of dots in a "halftone cell." The more dots printed in the cell, the darker the gray. As the screen frequency gets higher (more cells per inch), there is less room for dots in the cell, reducing the number of shades of gray or color that can be generated.

In low-resolution printers, there is always a compromise between printer resolution (dpi) and screen frequency (lpi), which is the number of rows of halftone cells per inch. For example, in a 300 dpi printer, the 8x8 halftone cell required to create 64 shades of grays results in a very coarse 38 lines per inch of screen frequency (300 dpi divided by 8). However, a high-resolution, 2400 dpi imagesetter can easily handle 256 shades of gray at 150 lpi (2,400 / 16).

PRINTER RESOLUTION & MAXIMUM SCREEN FREQUENCYShades of     Gray or  --At printer resolutions--Cell  Colors  300 dpi  1200 dpi  2400 dpi4x4    16    150 lpi   300 lpi   600 lpi

  8x8    64     38 lpi   130 lpi   300 lpi

 16x16  256     19 lpi    75 lpi   150 lpi



Analog Vs. Digital
The analog world of commercial printing prints dots in varying sizes. The digital world prints in grids of dots. Increasingly, digital printers use techniques that overlap dots to achieve greater variability in dot sizes.
References in periodicals archive ?
Moreover, Toppan's new photomask enables binary-type wafer performance that matches the fine-pattern formulation and dimension accuracy of half-tone type wafers, produced with embedded attenuated phase shift masks.
Several new filters - in addition to the 110 existing filters - such as color match, half-tone, median, noise map, and turbulence; and
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The dominant contract-proofing technologies today are the digital half-tone proofing systems and continuous-tone color proofing technologies.
After transmission of the files to a YARC Internet Server, a half-tone proof would automatically be created, and, upon verification of that proof, the CTP plates manufactured for the printing press.
Minolta RealTone technology enhances half-tone and line screen resolution for more photo-realistic images and better color management.
enhances tone images with 256 gradations per dot which produces sharp text, detailed photos and half-tone reproduction.
Scanner Control Sheets, which contain machine-readable codes, control various scanning functions automatically, including Simplex or Duplex scanning and text or half-tone mode operation, as well as separate pages into folders.
Scanner Control Sheets, which contain machine-readable codes, control various scanning functions, including Simplex or Duplex scanning and text or half-tone mode operation, as well as separate pages into folders.
FM screening technology differs from conventional screening methods in that it uses dots that are significantly smaller than conventional half-tone cells, resulting in enhanced detail.
The majority of postcards made at the turn of the twentieth century were mass-produced lithograph or letterpress half-tones, but the Eastern Illustrating & Publishing Company produced "real photo postcards" in the form of silver gelatin prints made by exposing the negative onto photo paper card stock and developing it in a traditional wet darkroom.