Ph.D. Tezi Görüntüleme

      In the scope of the thesis, the problem of tamper localization that may be made by unauthorized persons on medical images has been examined. In order to solve these problems, new methods for tamper localization on medical images have been proposed. The Least Significant Bit and the reversible method Difference Expansion are combined for the first time to increase the number of expandable blocks. Increasing the number of expandable blocks has increased the data embedding capacity. In this respect, the size of the Region of Interest which is the general problem of the methods proposed in the literature has been enlarged. Existing medical image watermarking systems are designed for image types such as Computed Tomography, Magnetic Resonance Imaging and Ultrason. There is not any method for watermarking Thermal Medical Images which has no harm to human health and become popular. Current methods are not applicable due to the characteristics of thermal medical images. Considering the properties of thermal images, a watermarking system based on Integer Wavelet Transform and Difference Expansion has been developed. Furthermore, for the first time in medical image watermarking systems, the robustness of data required for the watermark extraction has been increased by using secret sharing mechanisms. Difference Expansion that is a spatial domain technique was first applied to the frequency domain technique Integer Wavelet Transform coefficients. With this technique a large increase in the number of expandable blocks has been achieved. Therefore, the amount of data that can be hide in the medical image has been increased.