Effect of image sharpening on radiographic image quality

The image sharpening algorithm, unsharp masking (USM), may cause artifacts that reduce the diagnostic value of digital images. It may create overshoot artifacts that can be misdiagnosed as pathosis or prosthesis misfit. The effect of this image sharpening and the extent of overshoot artifacts on image quality requires investigation.

The purpose of this in vitro study was to evaluate the effect of USM on digital dental radiographic quality and to demonstrate the extent of overshoot artifacts.

Three digital sensors (2 complementary metal-oxide-semiconductors and 1 photostimulable phosphor) were exposed using a digital dental quality assurance imaging phantom to evaluate contrast resolution, spatial resolution, and dynamic range. The 3 sensors were again exposed without the phantom to determine the degree of radiographic noise. Each image was sharpened and then highly sharpened. Overshoot was measured, and images were compared using the Friedman 2-way ANOVA analysis.

Image sharpening significantly affected spatial resolution and noise. Conversely, dynamic range and contrast resolution were not significantly affected by image sharpening. Overshoot artifacts increased with image sharpening.

Image sharpening improves visual image quality but significantly increases overshoot artifacts that adversely affect radiographic diagnosis. Data from this study indicate that image sharpening causes artifacts that could negatively affect accurate diagnosis.