Stationary Grid Pattern Removal Using 2-Dimensional Technique For Moire-Free Radiographic Image Display

摘要

The striped patterns are superimposed in the radiographic images exposed with the stationary grid. When those images are displayed on a monitor, the scaling process causes the low frequency moire patterns overlapped over the object shadow. To prevent these moire patterns, it is necessary to remove the grid patterns before scaling process. The 1-dimenstional filtering can remove the grid pattern, on the other hand it removes some diagnostic information too. We developed two different grid pattern removal processes using 2-dimensional technique. The 2-dimensional technique can localize the information 2-dimensionally in frequency domain, so that the localized information includes the grid information. So the 2-dimensional method can remove the grid pattern with minimum loss of diagnostic information. Quality of images processed by the two 2-dimensional methods and the conventional 1-dimensional filtering method were evaluated. No grid patterns were observed in the images processed by three methods. However, as compared with the 1-dimensional filtered image, the images processed by the 2-dimensional methods were much sharper and have more detail information.