PC Hardware A Beginner’s Guide

(^264) PC Hardware: A Beginner’s Guide
The number of bits in the color depth determines the number of colors that can be
displayed. For example, 8-bit color uses 8-bits to number each of the colors. In binary
numbers, the range of numbers available in 8 bits is 00000000 to 11111111, or the range in
decimal numbers of 0 to 255, which represents different 256 colors. The colors included in
the color palette for a particular color depth are represented in the binary values stored
in the number of bits available.
To determine the number of colors that a particular color depth includes, it’s repre-
sented as the largest binary number that can be displayed in the number of bits of the color
depth plus one. This means that a 16-bit color depth can display 65,536 colors (or 2^15 + 1),
the 24-bit color depth has over 16.7 million colors that each pixel could conceivably display,
and a 32-bit color depth supports over 4billioncolors. Depending on the PC, video card, and
monitor, either 24-bit or 32-bit is typically designated as True Color setting.
NOTE: The human eye cannot distinguish beyond 16 million or so colors. Above that the eye may
have difficulty discerning the colors of two adjacent pixels.

Aspect Ratio

Another measurement used to define the capabilities of the video display is its aspect ratio.

This is the ratio of horizontal pixels to vertical pixels used to create the display. The stan-

dard aspect ratio is 4:3 (read as 4 to 3), which is used for 640 × 480, 800 × 600, and 1280 × 768

resolutions. The aspect ratio determines how well certain shapes, such as circles, can be

drawn on the screen without distortion. As a user, the aspect ratio isn’t a big thing, but if

you are a graphics designer or programmer, it can make a difference on the quality of the

image produced by the video card.

How Much Video Memory Is Needed?

Most video cards available today include between 8MB and 32MB of video RAM. Some

high-end cards are available with as much as 64MB of video RAM. There are opinions

that 64MB is far more than is needed, but others, especially the 3D crowd, think that this

may soon not be enough.

The following formula is used to figure the amount of video RAM needed for a

particular system:

Resolution * (Color Depth / 8) = Video RAM required

The color depth is divided by 8 to convert the calculation into bytes, which is the common

measurement for video RAM.

For example, if you are using 24-bit color depth with a resolution of 1024 × 768, the

calculation for the minimum amount of video RAM needed is:

1024 * 768 = 786,432 (pixels in the resolution)

24 / 8 = 3 (bytes in the color depth)

786,432 * 3 = 2,359,296 (bytes of video RAM needed)