Display Types
Your computer uses a display adapter, or video card, to display words and images on your computer monitor. The type of display adapter determines the number of colors that can be displayed. You were probably "wowed" by the number of bits your video card had when you purchased your home computer, but had no idea what it meant. Well, just like most other computer hardware, the bigger the number the better off you are.
Early video cards only displayed 16 colors; then 256 colors. Today's video cards can commonly display 65,536 colors or more. But what is the difference and why should you care?
First we'll answer what the difference is. Let's start out with a rainbow. Hopefully you are using a computer that can display at least 65,536 colors or you will not see the difference.
Here is what the same exact rainbow would probably look like on a computer that can only display 16 colors, or uses 4-bit color.
At one time that would have been great! Now here's what the same rainbow might look like on a computer that can display only 256 colors, or uses 8-bit color.
While this is better, it still is not a good representation of the actual rainbow. Some video cards might dither, or mix two component colors using a pattern of dots, the undisplayable colors of the rainbow to make it look better. Finally, if we look at the rainbow on a computer that can display 65,536+ colors, or uses 16-bit, 32-bit, or true color, we can get a good representation.
So the difference is in the number of colors that can be displayed.
Now, why do you care? You should care because you probably want your viewers to see exactly what you see when you design the page. If you design your Web page on a computer that is set to display true color, you could have some unpleasant surprises when you look at it on a computer that displays 256 colors. Therefore, you should keep in mind your viewers that may not have the best video card in the world. For this reason, a web-safe palette has been established containing 216 colors that are not only guaranteed to look good on any PC that can display 256 colors, but also on any Apple Macintosh computer. Take the time to browse the Web Central Web Safe Palette to select some colors that will look good anywhere. And if you are concerned about any photographs you want to include on your pages, don't sweat. You can still use any palette you want since any viewers that are using only 256 colors aren't expecting photos to look photo-realistic.
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