Bit-mapped image -- an image formed by a rectangular grid of pixels. 

Brightness -- the measure of overall color intensity. The lower the brightness, the closer to black the image will be; the higher the brightness the closer to white the image will be.

CCD -- Charged Couple Device. Most scanners and digital cameras use an array of these photosensitive elements to convert light into electrical currents which get converted into digital format. Compare CCD arrays to the grains of silver oxide on film -- film has a much higher resolution and, because of its random grain structure, a warmer feel.

CMYK -- Acronym for Cyan, Magenta, Yellow and Black, the four ink colors used in commercial or process printing.

Continuous tone -- an image with various shades of gray or color, such as a photograph.

Contrast -- the relationship between light and dark areas of an image. The more extreme the difference, the greater the contrast.

DPI, dots per inch --  a unit of measurement used to gauge the resolution of printers and imagesetters. More DPI means higher resolution and greater detail.

Dynamic range -- generally used to describe a scanner's ability to pick up shadows and highlights. 

Flatbed scanner -- a scanner designed to capture images from flat, generally opaque, media like paper. The scanner head moves across the image. 

EPS -- Encapsulated PostScript, a file format used to store high resolution pictures.

GIF -- a web file format best suited for images that have large areas of consistent color and tone.

Gamma -- gamma measures contrast that effects midtone grays. It is a logarithmic correction to the computer's linear representation of tone which better approximates the way people actually see dark to light tones.

Halftone -- a pattern of dots of different sizes used to simulate continuous tone photographs.

Interpolation -- a technique used by scanner software or hardware to simulate higher resolution. Compare to optical or true resolution.

LPI, Lines per inch -- a measure of page resolution that refers back to the photographic screens which were used to create the dot patterns. Under PostScript, it refers to the cells that aggregate printer or imagesetter resolution.

Optical Character Recognition (OCR) -- the process of scanning paper text and converting the resulting image into editable electronic text.

JPEG -- A form of image data compression supported by the Joint Photographic Experts Group. Best suited for photographs or high quality images.

Pixel -- the smallest element of a display that can be assigned independent color and intensity. The area of finest detail that can be reproduced on the recording medium. One dot on the computer screen.

PPI, pixels-per-inch -- screen resolution, the number of pixels a monitor uses to display an image. Although monitors display at different resolutions, 72 ppi has come to be accepted as a compromise measure of screen resolution.

PostScript-- a page description language used by graphics software to output image files. A printer must have a PostScript interpreter chip to translate the postscript code into the dots the printer places on the page.

RGB -- Red, Green, Blue the three additive colors of light used in computer screens and scanners.

RIP -- Raster Image Process is that process by which a printer or imagesetter translates a page description language such as PostScript into the physical dot structure which will define the image on the page.

TIFF Tagged Image File Format -- an industry-standard image-file format supported by many applications. This uncompressed file format is best used for high quality print output and for archival scans.