Efficient compression of encrypted grayscale images

Consider an image that has been encrypted uncompressed. The data compression algorithms are ineffective because the encryption masks the source. To reduce the size, distributed source coding technique is used without requiring the data be compressed prior to encryption. Under some reasonable condition, neither the security nor the compression efficiency will be sacrificed by performing compression in the encrypted domain. The design and analysis of a practical lossless image codec, where the image data undergoes stream-cipher based encryption before compression. An efficient way to compress encrypted images is through Resolution-progressive compression (RPC), where RPC can be used for both interframe and intraframe correlation. Lossless compression of encrypted sources can be achieved through Slepian-Wolf Coding. This work proposes a resolution progressive compression scheme which compresses an encrypted image progressively in resolution, such that the decoder can observe a low-resolution version of the image as well as video, study local statistics based on it, and use the statistics to decode the next resolution level. The system is implemented by using Mat lab.