5.5. Brightness-Contrast

The Brightness-Contrast tool adjusts the brightness and contrast levels for the active layer or selection. This tool is easy to use, but relatively unsophisticated. The Levels and Curve tools allow you to make the same types of adjustments, but also give you the ability to treat bright colors differently from darker colors. Generally speaking, the BC tool is great for doing a "quick and dirty" adjustment in a few seconds, but if the image is important and you want it to look as good as possible, you will use one of the other tools.

In GIMP 2.4, a new way of operating this tool has been added: by clicking the mouse inside the image, and dragging while keeping the left mouse button down. Moving the mouse vertically changes the brightness; moving horizontally changes the contrast. When you are satisfied with the result, you can either press the OK button on the dialog, or hit the Return key on your keyboard.

5.5.1. Activating the Tool

You can get to the Brightness-Contrast tool in two ways:

  • In the image-menu through: ToolsColor ToolsBrightness-Contrast or ColorsBrightness-Contrast,

  • by clicking the tool icon: in Toolbox, provided that you have installed color tools in Toolbox. For this, please refer to Section 1.7, “Toolbox”.

5.5.2. Options

Figure 14.136. Brightness-Contrast options dialog

Brightness-Contrast options dialog

Presets

You can save the color settings of your image by clicking the Add settings to favourites button

The button opens a menu:

Figure 14.137. Preset Menu

Preset Menu

which lets you Import Settings from File or Export Settings to File, and gives you access to the Manage Save Settings dialog:

Figure 14.138. Manage saved Settings Dialog

Manage saved Settings Dialog

Brightness

This slider sets a negative (to darken) or positive (to brighten) value for the brightness, decreasing or increasing bright tones.

Contrast

This slider sets a negative (to decrease) or positive (to increase) value for the contrast.

Edit these settings as Levels

To make your work easier, this button lets you turn to the Levels tool with the same settings.

Preview

The Preview check-box makes all changes to the brightness and contrast dynamically so that the new level settings can be viewed immediately.