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7. The Menus / 7.6 The Tool Menu

### 7.6.38 Levels

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 Correction tries to find the optimal settings for the source range:

- The symbol adjusts the range of the current channel.
- The symbol adjusts the range of the single color channels.
- The gear symbol allows you to control the precision of the two auto modes. The values specify the percentage of the number of pixels that may be discarded when the limits are calculated automatically.

Output Levels controls the destination range.