Exposure Correction

This dialog corrects exposure problems in a picture. You will be surprised at the positive effects the following 4 tabs can have on many of your photographs:

Auto

Performs automatic contrast adjustment. The contrast is adjusted automatically by stretching the histogram between the minimum and the maximum optimized values. The Stretch All Channels option is provided in case you want to stretch each color channel separately.

Example of Auto Contrast:

Before After

Brightness

Performs 3 adjustments on Brightness, Contrast and Gamma. All 3 RGB channels are changed at same time with these operations.

Brightness
Brightness is a linear function applied to the histogram range. Increasing or Decreasing brightness will affect all values in the histogram of the picture by the same amount. So dark and bright pixels will result brighter or darker by the same amount.

Contrast
Contrast is also a linear function applied to the histogram range. Increasing or Decreasing the Contrast will modify differently dark and bright pixels. Increasing Contrast, dark pixels will become more dark and bright ones will become even brighter.

You can use the Un-linear contrast option to decrease the contrast, without loosing color information in the picture. To Adjust Brightness and Contrast more precisely you should use the Levels Tab, where it's possible to modify separately at the same time Shadows, Midtones and Hilights.

Gamma
Gamma correction is a non-linear correction that is based on an exponential formula. A Gamma curve represents the way usual monitors reproduce and display RGB values. This monitor conversion is necessary since the human eye has a nonlinear response curve, in fact it is more sensitive to variations in low light than to an equal variation in bright light.

Applying a Gamma correction curve can thus simulate the effect of viewing a picture on a brighter or darker monitor.

Example of correcting Brightness, Contrast, Gamma

Before After

Levels Tab

In the Levels Tab it's possible to regulate the Exposure, even for each RGB channel separately, by changing the amount of Shadows, Midtones and Hilights.

See the Histogram & Curves topic for more information.


Smart Flash

Sometimes, there are parts of the picture which are under-exposed and need to be corrected. To recover details in these dark regions, it's not useful to use one of the more common regulations, because we will risk to over-expose the part of the picture that doesn't need any correction.

In order to solve this problem, we invented a smart algorithm, which affects only parts of the picture that need to be brought to light. You can regulate the amount to be applied on the picture by simply using a slider.

The algorithm is especially effective in some situations that will always happen, no matter how good a camera you have:

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where there's strong sunlight shining into small streets (as seen in the example below)

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when you take indoor pictures without a flash, and the light through the window is very bright

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when you photographed someone against the sunlight

Example of Smart Flash

Before After

Important

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Remember, that correction tools permanently change the appearance of a photograph, and that some of the original information of the picture may be lost. While the algorithms in CodedColor are not as aggressive as in many competing programs, always make sure that it's not your monitor that is causing the apparent flaw. That way, you would actually ruin an image because of a badly adjusted monitor. If in doubt, it's a good habit to keep your original pictures in a backup folder.

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If you only want to apply Exposure corrections to certain parts of an image, you can create Selections or use the Retouch Brushes.

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When selecting parts of the image using the selection tools, all brushes and correction dialogs only apply to these selections. Selections can also have a feather, reducing the effect of the brush or correction close to the selection borders.

Related topics

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A short introduction to Histograms

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Before/After Tutorials