User Guide

GNU Image Manipulation Program
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TOOL OPTIONS DIALOG
Histogram Scale These two options have the same action as the logarithmic and Linear buttons in the Levels dialog.
Sample Average This slider sets the ‘radius’ of the color-picking area. This area appears as a more or less enlarged square when
you maintain the click on a pixel.
12.5.7 Curves Tool
12.5.7.1 Activate Tool
You can get to this tools in two ways :
• In the image menu through Tools → Color Tools → Curves.
• By clicking on the tool icon in Toolbox, if this tool has ben installed there (see Tools dialog.
12.5.7.2 Adjust Color Curves
Figure 12.74: Curves tool
Channel There are five options: Value for luminosity and contrast; Red, Green, and Blue for saturation; and Alpha (if your
image has an Alpha channel).
Reset Channel This button deletes all changes made to the selected channel and returns to default values.
Linear and Logarithmic buttons These buttons allow to choose the Linear or Logarithmic type of the histogram. You can also
use the same options in Tool Options dialog.