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.