D
dot area
The percentages of an area covered by a halftone dot ranging from no dot at 0% to a solid ink density at 100%. The size of the dots is stated in percentage of the area they occupy. A square dot at 50% creates a checkerboard pattern.
dot etching
A technique that physically reduces the dot sizes on film by emersion in acid, by using photographic overexposure on contact and dupe films, or by electronic etching or airbrushing on a computer. Dot etching is done to change hues in specific areas of the reproduction.
dot gain compensation
The technique of reducing the printing dot sizes of halftone separation films to compensate for the expected dot gain on press. The reduction is done mostly with the middletone controls as that is were the gain is the greatest.
dot gain The apparent dot size increases from the film to the printed reproduction. Dot gain can be simulated on a video monitor by adjusting the white point and gamma.
dot range
The total spread of dot sizes from the maximum size to the maximum size for a given film or device.
dot shape
The form of the halftone dot that may be intentionally varied from round to elliptical to square. Halftone dots are made with specific physical configurations to minimize dot gain and moire. The dot shape is varied to minimize the dot gain at the point where dots join one another. Elliptical dots minimize the sudden dot gain where corners of dots connect; they may connect in their short direction at 40% dot area and in their long direction at 60% dot area. Round dots, often used for newsprint, may not connect until 70% dot area.
double thick cover
Two thicknesses of regular weight cover papers pasted together
double-truck
US term to describe a newspaper plate that contains 2 pages. These plates are sometimes used when there is an image that crosses over from one page to another. Such a plate is called a “panorama plate” in the rest of the world.
doubling
A printing defect of lithographic caused by a mechanical problem on a press that results on a second set of dots printing. The defect appears as colour changes and a darker than expected reproduction.
downlink
The communication link sending data down from a satellite to an earth station.
download
Sending information to another computer. For example, downloaded fonts are sent from a computer to a laser printer or high resolution imagesetter.
downloadable font
A digital typeface that can be output to a digital output device, such as a laser printer or an imagesetter. Some digital fonts have been rendered only for display on computer monitors and are referred to as screen fonts.
DPI
Abbreviation for Dots Per Inch, a measure of resolution. When dpi is discussed by desktop publishers, they are actually referring to the number of spots per inch that can be input on a scanner or output on an imagesetter. Dpi does not refer to halftone dot. Halftones are specified in lines per inch.
drift
Motion along the axis after input stops
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