Computer display

A computer display, monitor or screen is a computer peripheral device capable of showing still or moving images generated by a computer and processed by a graphics card. Monitors generally conform to one or more display standards.

As with television, several different hardware technologies exist for displaying the actual image :


Nineteen inch (48 cm) Viewsonic
CRT computer monitor


A modern CRT display has considerable flexibility: it can often handle all resolutions from 640 by 480 pixels (640x480) up to 1600 by 1200 pixels (1600x1200) with 32-bit colour and a variety of refresh rates.

The sharpness of a display is described by its dot pitch. In general, the lower the dot pitch, (ie. .24), the sharper the picture will be.

Some technical circles prefer the name "display" to the word "monitor" (perceived as ambiguous alongside the other senses of "monitor" meaning "machine-level debugger" or "thread synchronization mechanism"). Computer displays have also been known as visual display units or VDUs.

Early CRT-based VDUs without graphics capabilities gained the label 'glass teletypes', because of the similarity to their electromechanical predecessors.

Monochrome displays can only display one colour either as on or off. Grayscale displays can show only levels of a single colour. In both cases the display usually uses green, orange (amber) or gray (white).

Colour monitors may show either digital colour (each of the red, green and blue signals may be either on or off, giving eight possible colours: black, white, red, green, blue, cyan, magenta and yellow) or analog colour (red, green and blue signals are continuously variable allowing the display of any combination). Digital monitors are sometimes known as TTL because the voltages on the red, green and blue inputs are compatible with TTL logic chips.

Most modern computer displays can show thousands or millions of different colours in the RGB colour space by combining red, green, and blue dots in varying intensities.

Some display technologies (especially LCD) have an inherent misregistration of the colour planes, that is, the centers of the red, green, and blue dots do not line up perfectly. In 2001, software designers began to exploit the misregistration to produce sharper images: Microsoft's ClearType™ provides an example.

Moving texts can appear in italics, even when the display resolution is too low to show static italics: a fractional time delay causes an apparent corresponding shift of a fraction of a pixel.

See also: gamut, multisync.




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