Television

14 Pages 3543 Words

for white. The scene is divided into 15 scan lines numbered 0 through 14. The scene is focused on the light-sensitive area of a vidicon tube or CCD imaging device that scans the scene one line at time, transmitting the light variations along the lines as voltage levels. Where the white background is being scanned a 0 volt signal occurs. When a black picture element is encountered a 1 volt level is transmitted. The electrical signals derived from each scan line are refereed to as the video signal. They are transmitted serially one after the other until the entire scene has been sent. Since the scene contains colors, there are different levels of light along each scan line. This information is transmitted as different shades of gray between black and white. Shades of gray are represented by some voltage level between 0- and 1-V extremes represented by white and black. The resulting signal is known as the brightness, or luminance and is usually designated by the letter Y. Resolution in a video system is measured in terms of the number of lines def...