Abstract
Compressing the encrypted images is considered an important issue in many applications such as cloud computing. From this perspective, this paper introduces an efficient approach for compression processing of images in the encrypted domain. The images are optically encrypted using the Double Random Phase Encoding (DRPE). The Joint Photographic Experts Group (JPEG) and the Set Partitioning in Hierarchical Trees (SPIHT) compression schemes have been used to compress the encrypted images. The process starts by converting the original image into an optical signal by an optical emitter like an optical source and encrypting it with DRPE. The DRPE applies two-phase modulations on both time and frequency domains to get the encrypted image. The JPEG and SPIHT compression techniques are utilized with different bit rates. The effect of compressing encrypted images with the DRPE is studied. Security analysis results show that the encrypted images using the DRPE are adequately compressed by SPIHT at a low bit rate, and can be adequately compressed by JPEG at a high bit rate. Also, experimental outcomes and security study prove that the multipurpose encryption and SPIHT compression scheme is more secure and effective.