Window level is another interesting feature of DICOM standard. Window level is used to transform the pixel value in DICOM file to pixel value shown on the screen. For example, DICOM modality of CT often export 12 bit images, however, LCD screen can only display 8 bit image. In order to display 12 bit image on 8 bit display, a transformation is necessary. 

In diagnostics, not all pixels are of the same level of importance. Adjusting the window level to show bones can help highlight the defects in the bones, adjusting window level to show fluid can help identify infection and other metabolism disorder. As a result, window level is a very important parameter set during the visualization of the DICOM based medical image.