7. The Menus / 7.6 The Tool Menu

7.6.33 Histogram Correction

The histogram finds out, how often each component is found in an image. By equalizing the distribution of the components, an image with more contrast is created.

The dialog of the histogram can display different distributions. You can switch between hue, intensity and saturation.

Gamma controls whether the compensation happens linear or is strengthened or weakened.

The large curve is showing the distribution of the selected component. If you chose - for example - intensity, the left side corresponds to 0% (lowest intensity) and the right side with 100% (highest intensity). In the curve there are two green lines that can be dragged with the mouse. They are the source range and control, what range of the current distribution will be. The source range can be changed by the two text fields below the curve field, too.

The small preview is showing the result of the compensation.

Auto tries to find the optimal settings for the source range.

Output Levels controls the destination range.