CertiGuide to A+ (A+ 4 Real)  9  Chapter 9: Graphic Cards

Chapter 9: Graphic Cards 1 Colors on the Computer

The basic building block of any graphic image is a pixel, a contraction of "Picture Element", arranged in precise rows and columns. The number of rows and columns of pixels is referred to as the "resolution" of the image and is usually expressed by the number of horizontal pixels (rows) multiplied by the number of vertical pixels (columns), for example: 800*600, 1024*768, 1152*864. Note that these resolutions are sized at a 4:3 ratio. The reason for this is that monitors are manufactured with a 4:3 aspect ratio, therefore for a pixel to appear square it must appear at the same 4:3 width to height aspect ratio.

However, the resolution alone defines nothing except the physical size of the image. Each of these resolutions also has an associated "bit depth", which defines the number of colors that can be displayed. The bit depth refers to how many bits of data are associated with each pixel and are available to store a colour value. A 24 bit image, commonly referred to as "true colour", allows for the storage of 24 bits of data per pixel. To clarify the measurement, there are of course 8 bits in every byte. This raises the question of how colors are defined.

Chapter 9: Graphic Cards 1 Colors on the Computer