Codestream Domain Scrambling of Moving Objects Based on DCT Sign-only Correlation for Motion JPEG Movies

This paper proposes a moving objects scrambling method for Motion JPEG movies that consists of two parts: a moving objects detection based on DCT sign-only correlation (DSOC) and a partial scrambling. DSOC is the correlation of the positive and negative signs of DCT coefficients. Utilizing the codestream structure of Motion JPEG movies and the relation between motion and DSOC, the proposed moving objects detection is achieved in codestream domain. The proposed scrambling is also achieved in codestream domain by inverting signs of DCT coefficients that each sign is independently encoded as one bit. The codestream domain processing in this method serves low processing time and keeps coding efficiency. Moreover, the proposed method completely descrambles scrambled codestreams to the original without any knowledge on the position and shape of moving objects. Simulation results show the effectiveness of the proposed method.