Resolution

Resolution

Definition
Resolution is the number of pixels per unit of area. In a monitor, this is the number of pixels the graphicscard describes the desktop with expressed as a horizontal and vertical figure. A display with a finer grid contains more pixels and has a higher resolution therefore it is capable of reproducing more detail in an image. This allows more of an image to be seen, reducing the need for scrolling or panning. The two most common resolutions are SVGA (800x600 pixels) and XGA (1024x768 pixels).

Measurement
Resolution is measured in pixels - which is an abbreviation for picture element. The pixel is the smallest unit that can be given a color intensity in a raster grid, The pixel is represented by some number of bits (usually 8, 16 or 24) in the frame buffer. It is illuminated by a collection of phosphor dots in the CRT that are struck by the beams of the electron gun. Resolution is expressed as a horizontal by vertical figure.

Types

CGA (Color Graphics Adapter)
Invented for the first IBM PC, CGA is a low-resolution video display standard.
Its highest resolution mode is 2 colors at a resolution of 640x200.

EGA (Enhanced Graphics Adapter)
The IBM standard for color displays prior to the VGA standard.
It has a specified resolution of 640x350 with up to 256 colors and a 9-pin (DB-9) connector.

VGA (Video Graphics Array or Video Graphics Adapter)
When it was introduced, VGA quickly replaced earlier standards such as CGA and EGA and made the 640x480 display showing 16 colors the norm. Since its introduction, manufacturers have extended the VGA standard to support more pixels and colors.

SVGA (Super-VGA)
It currently indicates a capability of 800x600 or greater, regardless of the number of colors available. When SVGA first came out it was used to describe graphics adapters capable of handling a resolution of 800x600 with support for 256 colors or 1024x768 with 16-color support.

XGA (eXtended Graphics Array or Extended Graphics Adapter)
Today it describes cards and monitors capable of resolutions up to 1024x768, regardless of the number of colors available. When it was introduced in 1990, as an IBM graphics standard, it provided a screen pixel resolution of 1024x768 in 256 colors or 640x480 in high (16-bit) color.

SXGA (Super XGA)
A screen resolution of 1280x1024 pixels, regardless of the number of colors available.

UXGA (Ultra XGA)
A screen resolution of 1600x1200 pixels.

Important Things to Remember
A monitor should give a stable display at the chosen resolution and color palette*. An unstable display can cause the screen to shimmer or flicker. This can cause headaches, itchy and/or painful eyes, and migraines particularly when most of the picture is showing white. The graphics card driving the monitor should also be taken into account. If the monitor cannot lock onto the signal, then having an extremely high performance graphics accelerator that is capable of ultra high resolutions at high flicker-free refresh rates is unnecessary.

*Color Palette - Also called a color lookup table (CLUT), index map, or color map, it is a commonly-used method for saving file space when creating color images. Instead of each pixel containing its own RGB values, which would require 24 bits, each pixel holds an 8-bit value, which is an index number into the color palette. The color palette contains a 256-color subset of the 16 million unique displayable colors.