The level / window settings define the linear mapping of the gray values of the CT volume to the gray values of the computer screen, ranging from zero to 255.
The level / window tool is used to change the settings for the current image. Interactively drag the cursor to adjust the contrast and brightness of the shown image or set the level/window according to specific presets.
Notes
Level / window settings are applied to all CT slices simultaneously. However, you can distinguish between settings for displaying CT slices and settings for the visualization of X-ray images.
When working in the Panoramic workspace [F5] or [fn+F5] and when changing the level / window manually by dragging over a reslice in single slice mode, the remaining slices which are in single slice mode will change accordingly. For reslices in X-ray mode, the level/window values will not change. When dragging over a reslice in X-ray mode, only the slices in X-ray mode will be affected.
The level / window tool can also be used to change the range of a transfer function.