Gamma Correction Illustrated

Gamma correction can be used to correct a variety of exposure problems. This page illustrates some of the ways gamma correction can be used.

Gamma correction factors are always greater than zero. A correction factor greater than one can be considered a "positive gamma correction" since it adds light to the picture. Gamma correction factors less than one, on the other hand, subtract light from the picture, and can therefore be considered "negative gamma correction."

A gamma correction factor greater than one will lighten dark parts of the picture without excessively lightening the bright ones. This is useful for fixing underexposed images. It can also be used successfully on pictures with a lot of backlighting to bring out detail in the foreground.

Original Image

Gamma 3.0 Correction

While a gamma correction may yield an image that is technically correct, it is sometimes desirable to not apply the correction, to achieve an artistic effect.

Original Image

Gamma 2.0 Correction

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A gamma correction factor less than one will darken light parts of the picture without excessively darkening the shadows. This can be used to fix washed out (over exposed) pictures.

Original Image

Gamma 0.5 Correction

Sometimes different gamma corrections need to be applied to different parts of the picture. For the result to be a believeable image, the photographer truly has to be an artist: Finding the boundaries between the parts of the picture that need to be lightened and the ones needing darkening is relatively easy. The difficulty comes from making the boundaries disappear in a natural looking way so the viewer doesn't realize the picture has been manipulated.

Original Image

Gamma 1.5 Shadow Correction
Gamma 0.5 Cloud Correction

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