Linear or Curved Display of Digital Radiographs

• Published in: Oral Radiology 1998, Vol.14 (1), p.1-8
• Main Authors: Ann-Catherine MORNER, Ulf WELANDER, Gunilla TRONJE, William D. McDAVID, Hajime FUCHIHATA, Osamu TOKUOKA
• Format: Article
• Language: Japanese
• ISSN: 0911-6028

CCD detectors used in direct digital intraoral radiography have a linear dose response. When images are displayed on computer monitors a linear display function is also most often employed. Dentists using digital radiography have pointed out that the visual characteristics of such images are different from those of film based images. The aim of the present work was to study the effects of curving the display function. For this purpose 30 digital radiographs were selected, and a computer program was constructed by which the gray level display could be manipulated. Dentists at Osaka University, Osaka, Japan, and Karolinska Institutet, Stockholm, Sweden, were asked to manipulate the display of each individual radiograph so that it exhibited what subjectively appeared to be the best possible characteristics for diagnostic work. The viewers were in agreement in their preference for a curved display function for digital intraoral radiographs. Effects of the curved display are analyzed and discussed. It is concluded that from a purely subjective point of view the dose response function of digital intraoral radiographs should be curved in such a way that contrast is increased in areas with low exposure and decreased in areas with high exposure. Whether or not this has an effect on the diagnostic performance may be studied employing, for example, ROC techniques.