#DESKTOP GAMMA CONTROL TV#But some TV makers go their own way when labeling their gamma control. Typically, however, the most appropriate values were 2.2 or 2.4, depending on the program material and the viewing environment (a lower gamma number typically works best in a brightly lit room). The content producers and the public were free to choose assuming that the TV offered gamma control. Until recently there was no fully agreed-upon level for gamma, nor did gamma specify the actual peak luminance required of the image. But basically the higher the number the darker the perceived image. Where these numbers come from requires a mathematical depth we don't need to dive into here. Gamma in conventional SD and HD sources has been typically referred to as a number, such as 1.8, 2.0, 2.2, and 2.4. So why, with today's solid-state technology does this odd correction persists when it isn't really needed? Simple: over 75 years of content produced with that gamma, not to mention hundreds of millions of dollars in studio and consumer gear designed to work with it. Or at least if done properly it shouldn't! #DESKTOP GAMMA CONTROL FULL#That is, it doesn't alter either the full black or peak white level of the image. Notice from the graph that gamma affects the broad middle center of the brightness range. We refer to this as gamma, but the more accurate term, at the display side, is gamma correction. As shown in the opening figure, the goal was the straight thin line in the middle. To get a linear response an inverse correction was performed on the source material. It was very insensitive at the dark end of the range and more sensitive at higher levels. The CRT (cathode ray tube) technology available when television was first developed was anything but linear. That is, if you plot a graph with the percent of total luminance in the signal on the bottom (x-axis) against the luminance actually achieved by the set, it would be a straight diagonal line: 20% of the signal produces 20% of the total luminance, 40% of the signal produces 40% of the total luminance, and so forth. In an ideal world the brightness of the image on a video display will be directly proportional to the input signal. It's Gamma, and unless you're accustomed to turning on your new set and never touching any of the controls beyond volume (and if you're reading this that's probably not you) it's a control and a subject worth knowing more about. Most of our astute readers will be familiar with the term, but newbies and more casual readers who just bought their first new HDTV in 10 years have likely noticed that even on some lower-end sets a new control with a strange name has appeared in the settings menu.
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