green, and blue (RGB). These colors are additive primaries (in contrast to the subtractive primaries cyan, yellow, and magenta that are used in printing). In 1931, the Commission Internationale de l'Eclairage (CIE) set forth international standards for color measurement. It defined the wavelengths of colors: Red 700 nanometers (nm), green, 546 nm, and blue, 435.8 nm. In 1950, the FCC redefined the standard to better adapt it to the phosphors used in TV picture tubes. The FCC's red is 610 nm, green is 534 nm, and blue is 472 nm. The NTSC recognized the FCC's color definitions when it developed the 1953 standard for color telecasting. Three beams address three separate phosphor dots on the inside of the face plate Three beams pass together Magnetic coils change through a single hole the direction of all three beams at once Three electron guns (red-gree-blue) Electrical terminals Three separate beams converging on a hole in the shadow mask Metal "shadow mask" with 200,000 tiny holes Fiigure 5-7. Scanning in the Picture Tube (Michel Bayard). A chromaticity chart, shown in Figure 5-6, demonstrates that, in television, blending the primary colors can produce any color. However, it is not possible to create primaries themselves from other primaries. They are unique. SCANNING AND FRAMING Of course, the process of capturing an image for a television or video application involves the use of a camera. As do eyes, cameras scan a scene to detect, capture, and transform light waves into electricity. The first all-electronic camera was the image-orthicon tube that RCA introduced in 1941. The more compact and simple vidicon tube was developed in 1951. It trained an electron beam, a scanning point, on an image. The beam swept the image left-to- right and top-to-bottom to measure the scene's photosensitive surface. The History and Technology of Analog Video Conventional optical techniques are used to focus the light onto a target area at the rear of the tube's faceplate. The back of the target is coated with a transparent, electri