Development of the digital securewatermark for teleradiology environment

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In the environment of information disclosure, the generalipurpose 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) for embedding Original image source IDThe aim of this research is to develop the optimal watermark method and preserve the diagnositic 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. There were no definite merits of the correction in the scramble method. It depended upon the image processing.We used the majority correction method and the BCH code method to increase the detection ratio of watermark information, we could gain the detection ratio (40%) for the raw detection ratio (60%) by the error correction.