Enhancing the robustness of watermarked medical images using heuristic search algorithm

Nowadays, multimedia elements such as image, video, animation, audio, and software can be distributed in a short time anywhere in the world using internet technology. Content owners are concerned about copyright protection and authentication. Watermarking is one of the method to protect patient information in medical images such as magnetic resonance and ultrasound imaging. In the literature, there are several methods proposed using both frequency-domain (etc. digital cosine transforms (DCT), digital wavelet transforms (DWT), digital Fourier transforms (DFT), digital radon transform (DRT)) and spatial domain (least significant bits (LSB)) methods. Mostly digital wavelet transform based watermarking methods give very promising results after common attacks. In the DWT algorithm, scaling factor is used in embedding and extraction. A scaling factor is a number between 0 and 1 which has been determined by the user which is not efficient. We can use the brute force method which solves a problem by checking all the possible cases, but it is slow. In this work, we use simulated annealing heuristic search algorithm to find out the best scaling factor to reach more robust, transparent, high data capacity and resistant watermarking method in medical images. Experimental results show that simulated annealing-based scaling factor determination in frequency domain watermarking gives more robust, resistant, and transparent watermarked images.