Digitisation and display of intra-oral films

Abstract

Aim: To determine the optimal parameters for the digitisation and display of intra-oral radiographs.

Materials and methods: Six intra-oral radiographs (EP size 2 dental film, Eastman Kodak Co., Rochester, NY, USA) were digitised using an Arcus II image scanner (Agfa-Gevaert N. V., Mortsel, Belgium). Each film was digitised at 8 bits, with and without a film mask, using three scanner resolutions (200, 400 and 600 p.p.i.), resulting in six versions of each radiograph. Seven experienced observers were asked to evaluate the quality of the resulting images as they were displayed on a Nokia 445Xi monitor (Nokia Display Products, Helsinki, Finland). Monitor settings were varied by changing the colour palette and screen resolution.

Results: Digital images of masked films had a statistically significant (t-test with alpha 2 tail < or = 0.05) higher quality than those scanned without a mask. The best image quality was obtained at a resolution of 400 p.p.i. Display options were optimum with 256 colours and a screen size of 1152 x 864 pixels.

Conclusions: Better results were obtained when intra-oral radiographs were digitised with a mask at a resolution of 200 or 400 p.p.i. and displayed using 256 colours and the largest screen size possible. Further studies are needed to extend these results to other makes and models of scanner and monitor.