The Non-linearity Un-sharp Masking Method Applied to CR Image

摘要

The characteristic of digital CR medicine radiation image is different of common video image, because of its wide dynamic range、abundant detail and bad contrast, so it is necessary to enhance CR image to improve its visual quality to meeting the need of doctor diagnosis. Whereas the linear un-sharp masking enhancement algorithms over enhancing the contrast and lose image details, aiming at the defects, the nonlinear un-sharp masking enhancement method basis of the characteristic of CR medicine radiation image is proposed. The arithmetic enhances select frequency response in order to enhance CR image edge details; it can non-linear adjust factor K bases of CR image gray characteristic and make K changing with original image density, namely, K will minish at low density and will increase at high density, accordingly gain non-linear enhancement edge details of CR image. It contrasts the disposal result image of linearity and non-linearity un-sharp masking method, and experiment results demonstrate that the non-linear un-harp masking algorithm enhances CR image detail and the signal to noise ratio, the detail variance (DV) of the processed image was higher 2 times than the image enhanced by the linear enhancement algorithms, and the value of DV/BV was higher 2.3 times than the linear algorithms, moreover CR image enhanced has good visual effect, the method is fit for edge detail enhancement of CR medicine radiation image.