1. From raw image to screen display

The "raw" image provided by a digital detector is not usable as it stands, for several reasons:

• the detector has a number of "defects" that need to be rendered invisible on the screen. These may be genuine faults (dead pixels, for example), or simple calibrations that need to be carried out;

• the image must be modified to assist the radiologist in his analysis, based on a priori knowledge of the examination performed;

• the image must be brought to the screen, taking into account the characteristics of the screen and the ocular response curve.

For all these reasons, the image supplied by the detector undergoes digital processing before being displayed on a screen or printed on film (figure