There are three ways to alter the brightness or contrast for a raster layer.
- The most interactive and recommended method is described in the steps below. This method uses the Image Analysis window and allows you to change the brightness, contrast, and gamma for more than one raster layer at a time.
- The second method uses the Effects toolbar. To make this method interactive, you need to check the option to Allow interactive display for Effects toolbar on the Display tab on the Layer Properties dialog box.
- The third method is to enter the values on the Display tab on the Layer Properties dialog box.
You can also alter the gamma, which affects how much light is given to the image or how bright it appears. This value can be set similarly to the brightness and contrast values—on the Image Analysis window or on the Layer Properties dialog box.
- To view the Image Analysis window, click Windows on the main menu and click Image Analysis.
- Click one or more raster layers in the Image Analysis window.
- Next to either the Brightness
, Contrast 
, or Gamma
buttons, you can use the slider to increase or decrease the value or you can type a value in the text boxes.
- Optionally, click the Brightness , Contrast , or Gamma buttons to change them back to their defaults.