Window width and level controls are used to emphasize data values displayed in the Visualization pane. Window width is the range of values relative to the ranges center value, or level. The default window width is the entire dataset. The default level is the center value of the entire dataset. With the default window and level, all values in the dataset are visible in the viewer. Certain features of the dataset, bone for example, may be emphasized by changing window width and level values.

One way to change the window width and level is by using Window/Level slider controls located in the Visualization Settings pane's Planes tab. Figure 2.7 shows these controls. Two sliders are used to set the window width and level. It is also possible to type values by clicking on the text entry boxes displayed next to the slider controls.

The mouse can also be used to change the width and level. Press Button1 and drag up and down inside of a slice pane to change the level. Press Button1 and drag the mouse from side to side to change the window width.

The tooth dataset's values range from 0 to 1300. The dataset's default level is 650 and default width is 1300. To view only the enamel, set the window width to 77 and the window level to 942.

Figure 2.9. Window Width and Level Sliders