VIDEO ADAPTER

The video hardware that determines the resolution and color depth of screen images. A k-bit adapter can display 2 to the kth power colors. For example, an 8-bit adapter displays up to 256 colors whereas a 24-bit adapter can display over 16 millions colors in a single screen. In hypermedia authoring, problems are created when the color depth of the authored image is higher than the color depth of the user (customer, student, reader) computer. Mac and PowerPC computers will usually dither to make the image reasonably good for users, whereas PC users may have terrible images if their video adapters are too low in color depth. The same thing can happen if the user's PC screen resolution adapter is lower than the authored PC screen. These are terribly frustrating problems for authors and users. For this reason, most of the commercial PC graphics and video CD-ROM files are authored for lower video adapters than the author's video adapter. For example, the author may be capable of presenting a graphics image in 30 million colors in a resolution of 1024 by 768. The author may elect, however, to only use no more than 256 colors in standard VGA resolution in order to have better images on user computers with lower powered video adapters.