It's not a particularly technical term, but in context it could stand in for "intensity" of light, for example. A gamma curve is a graph of this function. It's curved because the light intensity readings we store in image files is non-linearly related to the actual light intensity - in fact it's logarithmic.
The curve itself, or some coefficients to a function describing the curve, are contained within a colour profile although a colour profile also contains other information. Part of the sRGB colour profile is describing how raw light intensity values are converted to the values that are stored in the image file. They follow this gamma curve. The "curves" command in Photoshop or GIMP can be used to apply any arbitrary curve function to the luminance values in your image.
Some things like the settings in your TV might have a "gamma" adjustment, the purpose of which is simply to apply such a curve to the luminance values throughout the image. Applying such an adjustment has the effect of lightening or darkening mid-tones while keeping the black point and the white point the same. This is often described as having the effect of "boosting shadows" if the mid-tones are boosted.
Gamma changes the difference between dark and light areas. Decreasing Gamma makes dark areas lighter and light areas darker. Increasing Gamma makes dark areas darker and light areas lighter. It's more akin to contrast than anything. Brightness decreases the range of lightness without changing the starting dark point. So decreasing brightness simply darkens, increasing brightness simply lightens.
When our eyes receive twice the photons, the visual sensation is not that of twice the brightness, it depends on the context so linearity here is an exception instead of a rule. Gamma is about translating between digital sensitivity and human eye sensitivity, providing many advantages on one hand but adding complexity on the other hand.
Therefore, we will not go further presenting technical details or other various aspects such as gamma encoding in file creation, gamma corrections on image display, differences between CRT and LCD monitors, and so forth. In other words, gamma optimizes the contrast and brightness in the midtones.
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Trending Search forums. What's new. New posts Latest activity. What's the difference between gamma and brightness? Thread starter Sporko Start date Feb 4, Sidebar Sidebar. Forums Hardware and Technology Graphics Cards.
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