Stereo Images Encryption by OSA & RSA Algorithms

The proposed new partial encryption schemes use a secure encryption algorithm to encrypt only part of the compressed data. After application of image compression algorithm the partial encryption will applied. For two pairs of different gray scale images with the size (256 ´ 256) pixels, only 0.0244%-25% of the original data is encrypted. As a result, we see a significant reduction of time in the stage of encryption and decryption.In the compression step, the Orthogonal Search Algorithm (OSA) for motion estimation (the different between stereo images) is used. The resulting disparity vector and the remaining image were compressed by Discrete Cosine Transform (DCT), Quantization and arithmetic encoding. The image compressed was encrypted by RSA algorithm. The decoded images then compared with the original images.Good results showed in the experimental results of Peak Signal-to-Noise Ratio (PSNR), Compression Ratio (CR) and processing time. The proposed schemes of partial encryption are fast, secure and not be reducing in compression performance of the selected compression methods. (paper)