Gamma Correction

Gamma correction is now available in most of the the software to drive LED lights, so support in the controllers is not required. Gamma correction is basically changing the brightness of the LED to match what you see on your computer. If you don’t have gamma correction, then you have to individually select the colors on your LED’s to match the desired color. This works OK for small pictures or just a few colors. However, if you software, like Xlights/Nutcracker that supports color blends, what you see on the screen does not match your display. Your LED display looks washed out and you don’t get the nice color blends. Also, if you ramp your lights up and down the display will go from bright to dark quickly.

The gamma correction measurement process is shown in this link (Link). This link shows how the gamma correction was measured for 2812B pixels (Gamma=255*(input/255)^(1/.45)) or a gamma of 2.22. The chart below shows the correction curve.

Gamma Curve

The three pictures below show a comparison of a picture on an LED matrix. The picture on the left has no gamma correction and is washed out. The picture on the right has gamma corrected.

Bill_Gates

LightHouseTulips

It is more difficult to see the benefits on a LED strip, since my camera tends to be washed with just a few bright spots in the field of view. Below is a comparison of RED on the strip at the following brightness values 255, 128, 64, 32. Notice that the gamma corrected strip on the bottom shows the brightness changes.

Red

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