HP Vectra XU 6/XXX HP Vectra XU 6/xxx, Guide to Optimizing performance - Page 44

Pixel Data 1 Your PC's Performance Features More Video Performance The graphics controller stores screens of data for output to the display in video memory. These screens of data are called frames and so your video memory is also known as a frame buffer. The pixel data stored by the graphics controller defines the color to be displayed for each pixel. The amount of data required for each pixel is determined by the number of displayable colors; if you are using only 256 displayable colors, each pixel needs eight bits to define its color (eight bits gives 256 possible combinations), while in true color modes, each pixel can require up to four bytes (32-bits). 8-Bit pixel data in video memory 24-Bit pixel data in video memory Pixel displayed in one of 256 displayable colors Pixel displayed in one of 16,7 M displayable colors The screen resolution determines how many pixels make up a screen for the display. The number of pixels required is typically very large. Even a standard VGA screen at 640 ! 480 resolution consists of over 300,000 pixels. Consequently, when writing a screen of pixel data to the video memory, the video controller is manipulating very large amounts of data. 38 English