컴퓨터적 집적영상과 셀룰러오토마타 기반의 3차원 영상 워터마킹 및 암호화

Abstract

In this thesis, we present a 3D optical image watermarking and encryption technique based on computational integral imaging and cellular automata. This thesis mainly contains two parts: In the first part, we present a 3D watermark based medical image watermarking scheme. Region of interest (ROI) of a medical image is an area including important diagnostic information and must be stored without any distortion. This algorithm for application of watermarking technique for non-ROI of the medical image preserving ROI. In this method, a 3D watermark object is first decomposed into 2D elemental image array (EIA) by a lenslet array, and then the 2D elemental image array data is embedded into the host image. The watermark extraction process is an inverse process of embedding. The extracted EIA through the computational integral imaging reconstruction (CIIR) technique, the 3D watermark can be reconstructed. Because the EIA is composed of a number of elemental images possesses their own perspectives of a 3D watermark object. Even though the embedded watermark data badly damaged, the 3D virtual watermark can be successfully reconstructed. Furthermore, using cellular automata transform (CAT) with various rule number parameters, it is possible to get many channels for embedding. So our method can recover the weak point having only one transform plane in traditional watermarking methods. In the second part of the thesis, an optical image encryption method is proposed. Integral imaging can provide a feasible and efficient technique for optical image encoding system. The CIIR technique reconstructs a set of plane images along the output plane, whereas the resolution of the reconstructed images will degrade due to the partial occlusion of other reconstructed plane images. Meanwhile, CIIR is a pixel-overlapping reconstruction method, in which the superimposition causes the undesirable interference. To overcome these problems, we utilize the Bp neural network algorithm to eliminate the occlusion-disturbance. In the encryption, a computational integral imaging pickup technique is employed to record the input image to form an EIA. The EIA is then encrypted by combining the use of maximum length cellular automata (CA) encoding algorithm. The effectiveness of the proposed scheme is demonstrated with the aid of experimental results.