Below is a portion of the image of the peninsula in Charleston just south of the river delta. As you can see, the picture is actually made up of tiny squares, each of a different color. These squares are called picture elements, or pixels. The colors represent the relative reflected light energy recorded for that pixel.

Each pixel represents an area of land that is thirty meters by thirty meters. By adding up the number of pixels in an image, you can calculate the area of land in a scene. For example, if you count the number of green pixels you can calculate the total area covered with vegetation.