A purely graphical input device (i.e., a CAD/CAM CAE system digitizer for convening locations into storable electronic impulses) with a surface on which a location or a point is selected and then automatically converted into a digital x y coordinate suitable for transmission to a computer. A device for converting a signal of any type into a digital representation for storage in a computer or other related component or system.
A tablet or board-like device for converting analog electric signals of an absolute or relative position on the tablet surface to digital x,y coordinates. This process yields vector data consisting of points, lines, and polygons that will need to be edited. By positioning a pointing device containing a magnetic coil (cursor or pen stylus) on the tablet surface which is embedded with a grid of wires, a signal is generated. The resolution, or density of wires in the grid, vary from 1,000 to 10,000 lines per inch. Active surface sizes vary from 12 x 12 (A size) to 48 x 72 inches (E size), with prices ranging from $350 to $5,000. Related terms: digitizing mode, digital scanner, digitizer (video).
An optical device that translates electronic analog representations of images into an array of digital values called pixels. The value of a single pixel defines the level or shade of gray "captured" from a single point on a black & white image, or unique color if using color images. The resolution of a video digitizer is determined by the number of pixels (picture elements) that can be digitized by a system: commonly based on the powers of 2, with resolution ranging from 256 x 256 to 1024 by 1024 pixels. The word-size of an array, or number of bits used to represent each pixel, determines the number of unique gray values or colors that can be analyzed by a system, e.g. 8-bit words permit up to 256 shades of gray or colors, and 24-bit words up to 16.7 million shades or colors. A video digitizer may be used in place of a manual digitizer but, since it produces a raster-based image, software must be provided to convert the data into vector mode for plotters and monitors. Related terms: scanner, pixels, raster, image analysis.