How do these numbers alter what's being shown on the TV? Good question. The ISF continues to recommend 2.2 for TV watching in a dim viewing environment, but it recommends 2.4 for a completely dark room and 2.0 for a bright environment. As always, though, the system has evolved, and 2.2 is no longer considered the optimal gamma setting for every situation. For much of the history of digital displays, 2.2 has been the target gamma for the TV to perfectly offset the content and create a linear output. Therefore, TV manufacturers were forced to add gamma correction to make the digital TV act like a CRT TV. In today's digital world, TVs can offer linear output, but the gamma correction existed in so much content that - like many early tricks of the trade - the system needed to carry over to the digital realm. Disney WOW: World of Wonder Calibration Blu-ray Disc at. ![]() Read about Rethinking the Importance of Video Calibration at.Learn more about video calibration here at.That's why you'll often see it referred to as gamma correction. Content creators decided to compensate for this by incorporating the exact opposite curve into the source to result in perfectly linear output. According to the Imaging Science Foundation, a 50 percent input signal level produced only about 18 percent light output (which corresponds to a numerical gamma of 2.5). However, that's not how CRT TVs behaved instead, it produced a nonlinear curve. If you imagine a graph showing the relation of light output (vertical axis) to input signal level (horizontal axis), the ideal result would be a straight diagonal line at a 45-degree angle extending from zero - i.e., 20 percent brightness at a 20 percent input signal level, 30 percent brightness at a 30 percent input signal level, etc. ![]() The gamma curve dates to back to the days of CRT TV. What is gamma, what do those numbers mean, and which one is the right choice for your system? We're here to answer those questions for you. Unless it's an entry-level model, your TV probably includes multiple gamma options in the Picture setup menu, with numeric choices that generally range from 1.8 to 2.6. If you've read a lot of TV reviews (or even just few, actually), you've likely seen mention of a TV's gamma, a performance characteristic that helps determine the overall accuracy of the grayscale.
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