Quote:
Originally Posted by rockovids
not sure about the "GAMMA" setting, seems to affect brightness?
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To give a vastly oversimplified explanation:
Gamma defines the overall brightness of an image, especially in the midtones. Graphically, in the spectrum RGB 0-255, the midle point is ~RGB 128. Raising or lowering gamma raises or lowers the middle range of the spectrum centered at RGB 128, with decreasing effect in the darkest area and decreasing effect in the brightest area.
Think of plotting all the pixel values of an image along a straight line. As a straight line, the brightness of all the pixels is about the same. If you raise gamma, the middle part of the line will curve upward. If you lower gamma, the middle of the line will curve downward. Raise gamma too high, and darks lose density while brights lose detail. Lower it too far, and darker parts will be obscured and the brightest parts will lose perceived brilliance.
Here is a techy article about gamma. Don't worry about the formulas. Just look at the images on the right-hand side.
https://en.wikipedia.org/wiki/Gamma_correction. More examples here:
http://www.colormatters.com/the-power-of-gamma.
Monitors also have gamma settings. An uncalibrated monitor out of the box almost always has gamma that is off-spec from the ideal, either too low or too high. Working in video or graphics with an uncorrected gamma will skew the results of the way your monitor displays an image. One effect of low gamma is colors that appear oversaturated. If too high, colors appear unsaturated (washed out). Making corrections with an uncalibrated monitor will affect the way your images display on other monitors.
Gamma is also affected somewhat by brightness and contrast controls. Brightness raises or lowers dark values. Contrast raises or lowers bright values. Each of the controls is less effective at the middle of the spectrum than at the dark or bright end, but both affect the midpoint to some extent.
Another oversimplified item: In RGB, the gamma of each color can be adjusted independently or all at the same time. In YUV, gamma affects only luma, which ultimately affects all colors at the same time. There is no independent gamma control for chroma in YUV.
There are some limited but basic LCD panel test charts at this website:
http://www.lagom.nl/lcd-test/. But the best way to correctly adjust a monitor is with a monitor calibration kit such as those from X-Rite or Spyder. Doing it with test patterns is iffy and difficult. Doing it by eye is impossible.
