Dual-energy X-ray Imaging in Combination with Automated Threshold Gabor Filtering for Baggage Screening Application

Abstract

With ever-increasing demands on the security screening procedures, improved detection of items of concern inside the bags and luggage continues to attract considerable interest. In this study dual-energy, X-ray images have been used in combination with Gabor filter noise reduction with a view to improvements in object visualization and automated detection. X-ray images were acquired from representative test items using 20 kV and 140 kV X-rays and Gabor filtering, with an automatic threshold level setting, was applied for image de-noising. The filter was applied in six different amplitudes and directions to obtain a fused image with the background fog removed which yielded higher image quality. Evaluation of the reconstructed images was performed by experienced operators who were able to confirm the achievement of the significant improvement in visualization-confidence of morphology and material differences between the objects. Also, quantitative analysis was applied to the processed fused image and statistically significant differences between low contrast regions of the image associated with powders and fluids with similar densities were detected. The results show that the method can be extended to achieve automated object material and shape recognition as a powerful tool in airport security screening.