Understanding Display Adapters

 

GRAPHICS TERMS

Pixel

The smallest controllable element on a screen. Consists of one red (R), one green (G), and one blue (B) phosphor. The pixel can be set to any color depending on the adapter, drivers, etc.

Resolution

Sharpness of the digital image. Associated with the 'dot pitch' a 'dot' is a pixel. The higher the resolution, the greater the number of pixels that can be displayed at one time. The resolution is represented as the number of pixels in a row times the number of pixels in a column. As video standards evolved, the resolution increased. Thus, VGA (video graphics array) supports 640x480 resolution while SXGA (super extended graphics array) and UXGA (ultra xga), both current standards, support 1280x1024 and 1600x1200, respectively. Below is a schematic of differing resolutions




Dithering

The system substitutes combinations of colors for colors the adapter cannot natively produce. This results in a degradation of image.

Color Depth

The number of colors an adapter can display. Represented by the number of colors or a term defining a number of colors:

- VGA color mode: 16 colors
- 256 colors: 256 shades of red, green, and blue. Uses 1 byte (8 bits) per pixel for color info.
- High Color: 65,536 (usually referred to as 65,000 colors). Uses 2 bytes (16 bits) per pixel for color info.
- True Color: 16,777,216 (usually referred to as 'millions of colors'). Uses 3 bytes (24 bits) per pixel for color info.

The more bits used for color info, the greater the color depth.

Rendering


The process of drawing the pixels by the hardware. The faster the video memory (the faster the frame buffer can be read from and written to), the faster the rendering. Gives the illusion of movement by refreshing each frame about 30 times per second. Associated with 3D.

For details on the specifics of rendering, click here.

3D Acceleration

A hardware engine on the adapter (the gpu) dedicated to executing the instructions to render 3 dimensional images. 3D accelerators draw millions of 'polygons' per second, delivering 3D without bottlenecking the main board CPU.

Anti-Aliasing

The act of smoothing objects such as diagonal lines, which can appear as 'stepped' instead of smoothly diagonal. The image is sampled over itself several times in order to remove the 'artifacts' (the steps), and create a smooth line.

DirectX

A Microsoft API (applications programming interface) that acts as an intermediary between the software application, and the hardware that it runs on. This allows application code to be independent of the hardware. The API handles the instructions from the app, and translates the instructions to be sent on to the hardware. Direct X is a programming environment in which multimedia apps can be developed. For the optimal Windows graphics, you must have the latest DirectX.

Click here to download DirectX.

Open GL

Originally an API developed for UNIX industrial systems, OpenGL is a standard used by many of today's games, and is generally platform-independent. Applications written in the OpenGL environment involve much more detailed control over primitive graphic elements (ie lines, triangles, etc) than in API's such as DirectX and Direct 3D.