A novel edge protective adaptive filter for high energy X-ray imaging technology

Impulse noise will greatly influence the quality of images in high energy X-ray imaging. This paper concludes the properties of impulse noise, proposes a probability model and a spatial model of impulse noise and realizes the computer simulation of impulse noise. In order to effectively eliminate impulse noise, an edge protective adaptive median (EP AM) filter is proposed according to the properties of impulse noise. EP AM filter classifies pixels into extreme noise, corrupted pixels and uncorrupted pixels and use different filters for different pixels. With the purpose of protecting the image edge, an edge detection algorithm embedded in EP AM filter is proposed. The determination of extreme noise in edges is stricter than in smooth areas. Through experiments, this method proves to be effective in the denoising of isolated, non-isolated impulse noise. In comparison with standard median (SM), adaptive median (AM), wavelet thresholding and center weighted median (CWM) filters, our method has superior performance when noise density ranges from 0.1 to 0.9. It produces satisfactory result when applied to high energy X-ray images with impulse noise.