Dual harmonic anti-scatter grid artefact removal for digital radiography

摘要

Use of low density anti-scatter grids with modern high resolution digital radiography detectors produces artefacts in the form of periodic stripes. We propose an approach for anti-scatter grid artefact removal in diagnostic digital radiography images. The approach is based on dual homomorphic filtering of spectral harmonics. We show that existing single harmonic methods are unable to remove periodic image artefacts completely, leaving image quality compromised. Adopting the conventional multiplicative grid model of image formation, we show that simple extension of the one harmonic approach leads to further artefacts and propose an alternative second harmonic removal filter. It is shown that the proposed algorithm produces superior image quality, both for non-clinical and clinical diagnostic x-ray images, compared to only first harmonic removal used in state-of-the-art algorithms.