| Gamma A display characteristic of CRTs defined by: Light = Volts ^ gamma where gamma is 2.35 plus or minus 0.1. CRTs usually have values between 2.25 and 2.45, and 2.35 is a common value. No direct-view CRTs have values lower than 2.1. CRT projectors exhibit different values; green tubes are typically at 2.2, while red is usually around 2.1, and blue can be as low as 1.7. Pictures destined for display on CRTs are gamma-corrected, meaning that a transfer characteristic has been applied to correct for the CRT gamma. Users of TV cameras have to accept the gamma characteristic supplied by the manufacturer, except for broadcasters who are able to adjust the curves that profile gamma correction. In this case video engineers adjust the gamma correction until they like the look of the picture on the studio monitor. Even so, no TV camera uses a true gamma-correction curve; cameras all use flattened curves with a maximum slope near black of between 3 and 5. The higher the slope, the better the colorimetry but the worse the noise performance. Genlocking The process of aligning the data rate of a video image with that of a digital device to digitize the image and enter it into computer memory. The machine that performs this function is known as a genlock. Geo Port A Geo port is a type of serial port on Apple computers. It provides an interface between a telephone line and the computer. The Geo Port Telecom Adapter Kit announced in late 1996 supports modem speeds of up to 28.8 Kbps and provides enhanced fax and telephone services when used with the Apple Telecom 3.0 suite of communications applications. Gouraud ShadingA shading algorithm that takes the 3 colors defined at each point of a triangle and smoothly interpolates them throughout the surface of the triangle. It is often used to make round objects look more round and smooth. |
