8.9. Luminosité-Contraste

8.9. Luminosité-Contraste
	8. Le menu « Couleurs »

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 Brightness-Contrast 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 want to use one of the other tools.

	Astuce
	Besides using the sliders you can also adjust the settings 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 press the Return key on your keyboard.

	Note
	Since GIMP 2.10, the Brightness-Contrast tool also works on indexed layers.

8.9.1. Activation de l’outil

Vous pouvez accéder à l’outil de deux façon :

In the image menubar through Colors → Brightness-Contrast….
By clicking the tool icon in the toolbox if this tool has been installed there. For this, please refer to Section 1.13, « Boîte à outils ».

8.9.2. Options

Figure 16.157. Boîte de dialogue des options de Luminosité-Contraste

Pré-réglages: « Presets » are a common feature for several Colors commands. You can find its description in Section 8.1.1, « Fonctions communes aux couleurs ».
Luminosité: Ce curseur permet de définir une valeur négative (pour assombrir) ou positive (pour éclaircir) et augmente ou diminue les tons clairs.
Contraste: Ce curseur permet de définir une valeur négative pour diminuer le contraste, ou positive pour l’augmenter.
Modifier ces paramètres en tant que Niveaux: Pour faciliter votre tâche, ce bouton vous permet de passer à l’outil Niveaux avec les mêmes paramètres.
Blending Options, Preview and Split view: These are common features described in Section 8.1.1, « Fonctions communes aux couleurs ».