Intensity Mappings: Linearization, Image-Based, User-Controlled

The objective of intensity mappings, functions from recorded intensity to displayed intensity, is to provide contrast in the display of features of interest in images where these features appear as regions of increased or decreased intensity. Three component objectives of such mappings can be identified: 1) device linearization, 2) emphasis of contrast in commonly occurring and accurately measured intensities, and 3) user-controlled mapping based on the importance of image features. Mappings of type 1, which immediately precede the display device, are designed to modify the device so that equal changes in the driving intensity value are equally perceivable. The importance of this mapping will be demonstrated, and the argument that by itself this mapping must improve displayed image quality will be refuted. A method of measuring the JND curve and of calculating this mapping from it will be discussed. A method for automatic determination of a mapping of type 2 consisting of a nonstationary modification of Cormack's mean pixel uncertainty minimization method [Phys. Med. Biol. 25(2)] will be presented. Methods for user control in the determination of mappings of type 3 will be briefly discussed.