eli5 what is a gamma curve?
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Maybe you’re asking about electronic image and video. Gamma is a mathematical function used to convert stored image data into display brightness. It’s used because electronic and digital image systems can only store a limited number and range of brightness values whereas our eyes can see a very wide range of brightnesses.
Gamma is a power function with the value of gamma giving the power used, typically around 2. Using exactly 2 just gives a square function so that stored brightness values of 1, 2, 3 result in displayed brightnesses proportional to 1, 4, 9. Cathode ray tubes, as used in old-style TVs, coincidentally and naturally have a gamma characteristic and that played a role in the original use of gamma in analogue video.
Familiar analogue and digital imaging standards like NTSC TV and JPEG and MPEG all use a gamma function in their operation.
As we move to high dynamic range (HDR) imaging, more complex functions are being used. We’re using greater precision to store the brightness values and the new functions turn these into an even greater range of brightnesses, so we can have very dark greys and very bright whites appear together. The principle still hasn’t changed much and the new generation of “transfer functions” are mostly fine-tuned versions of the old gamma systems.
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