ATI 9550 User Guide - Page 22

Glossary Alpha blending Anti-aliasing Back buffer Bilinear Filtering Bitmap When an image has an alpha value for each pixel, this tells how much to blend the colors from the image with the background colors. The lower the alpha values the more transparent the image looks. Method used to remove the jagginess of an image. When anti-aliasing is used, the edges of an image appear smooth and usually somewhat blurry. A type of offscreen memory used to provide smooth video and 2D graphics acceleration. This technique uses two frame buffers, often referred to as "doublebuffering". While one buffer is being displayed, a second buffer of the same size, the "back" buffer, holds the frame being worked on. Once a new frame is ready in the back buffer it is copied to the front buffer - the display screen. In this way, you will only see complete, smooth frames, and not the operations performed on them. In order to increase performance, all memory used for back buffers are on your ATI graphics accelerator card. When texture mapping is performed an image can become very "blocky" or "pixelated" when the texture is viewed close up. Bilinear filtering samples four texture pixels, takes the weighted average of these pixels and applies the average of these "texels". This blended color is used to provide a smoother looking texture. A bitmap is a graphics or character representation composed of individual pixels, arranged horizontally in rows. A monochrome bitmap uses one bit per pixel (bpp). Color bitmaps may use up to 32-bpp, depending on the number of colors desired. 19