D

densitometer

An instrument used by print shops and service bureaus to measure the tonal density of printed halftones .

density

The capability of an object to stop or absorb light. The less the light is reflected or transmitted by an object, the higher its density.

density range

The range from the smallest highlight dot that a press can print to the largest shadow dot it can print.

digital video (DV)

The configuration of video into a pixel-based media that can be interpreted and displayed on a computer monitor.

digitize

To convert analog image or video information to a digital format.

digitizer board

A special-purpose computer card that transforms video signals into image data. Image sources for this technology include television signals and the output from VCRs and traditional analog video cameras . Digitizer video boards are also called frame grabbers, because they receive the frames sent by the video image sources.

distort

To stretch a selection or layer contents along either of its axes. Unlike skewing, distortion is not restricted to a single border at a time.

dither

A method of distributing pixels to extend the visual range of color on-screen, such as producing the effect of shades of gray on a black-and-white display or more colors on an 8-bit color display. By making adjacent pixels different colors, dithering gives the illusion of a third color .

dodge

A technique used by photographers in the darkroom to overexpose or lighten specific areas of an image. In Photoshop, the Dodge tool performs a similar function by increasing the brightness values of pixels as you paint with it.

dot gain

A phenomenon in printing that causes dots to print larger due to the absorbency of the paper they are printed on. Dot gain creates darker tones or colors. Dot gain is reflected in an increase in the density of light reflected by an image.

dots per inch (dpi)

The measurement of the number of dots produced by a printer that defines the tonal elements of a halftone dot or stochastic screen. The dpi determines the resolution of printed output.

Droplet

A mini application that contains Actions. A Droplet can sit on the desktop or be saved to a disk file. You can apply an operation to a file or group of files by dragging the file or folder onto the Droplet s icon.

drum scanner

A type of scanner that uses a spinning drum. The image is taped to a drum that spins very rapidly while the scanner s sensors record its color and tonality information.

Duotone

An image that uses two inks. Duotone can add a wider tonal range in a grayscale image by using more than one shade of ink to fill in the gaps. Duotone curves let you control the density of each shade in the highlights, midtones, and shadows. Photoshop creates Duotones by applying the various curves that you ve defined to a single image.

Duotone mode

A Photoshop mode that displays Duotones, which are images that have been separated into two spot colors. Duotone mode also supports Monotone (images with one color), Tritones (images with three colors), and Quadtones (images with four colors). The Duotone Mode color information is contained on one color channel. Photoshop displays a preview that is an RGB simulation of the ink combinations.

DV

See digital video .