Digital Watermark method suitable for teleradiology in aspect of watermark tolerance and image degradation

点击翻译按钮获取中文摘要

In the environment of information disclosure, the general-purpose image format such as JPEG/BMP that does not require special software for viewing is suitable for carrying medical image information individually. These formats have no way to know patient information. We have therefore developed two kinds of ID embedding methods : one is Bit-swapping method for embedding Alteration detection ID and the other is data-imposing method in Fourier domain using Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) for embedding Original image source ID.The aim of this research is to develop the optimal watermark method and preserve the diagnostic performance of the image. The watermark has the information of the patient and institution. At a hospital, the embedded image can point the original image by the watermark and detect the alternation of the image.We used the discrete cosine transform (DCT) method for the preservation of the ID and the bit swap method for detection of the alternation. The suitable coefficients of DCT were (1,1) and (2,2) and the strength of watermark (Range) was about 40. For the bit swapping method the optimal bit plane was the least significant bit. In the error correction, the detection ratio of a watermark gain 10% by the Bose-Chaudhuri-Hocquenghem code method. In the majority correction, if the raw detection rate is 60%, the error correction recovered the 100% information.We found the suitable parameter for the DCT and DWT watermark methods ; they were (1) Range = 8 or 16 in DCT method at the coefficient (1, 1) and (2) Range = 2 or 4 in DWT method at 4 or 5 divided level and section LL. We analyzed these values in aspects of the tolerance for image processing and the image degradation by the watermark.