3D-DCT quantization as a compression technique for video sequences

The paper proposes a novel method to generate quantization values for 3D-DCT coefficients. Such quantization values are important as they would affect significantly the extent of the compression achieved by any 3D-DCT based video compression scheme. It was found that the distribution of the dominant AC coefficients spread along the major axes of the 3D-DCT cube. The coefficient distribution can be modeled by dividing the cube into two regions, one for most of the significant coefficients and the other for the high frequency coefficients which can be discarded. The quantization values are computed by using an exponential function. The same function is also used to determine a scan order of the 3D-DCT coefficients, which is better than a three dimensional zig-zag scan method in general. Experimental results show that the proposed method can produce good visual quality videos and can achieve an attractive compression ratio of 16:1 by quantization alone.