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Prediction of discrete cosine transformed coefficients in resized pixel blocks

A hybrid model was developed to predict the zero-quantized discrete cosine transform (ZQDCT) coefficients for intra blocks in our previous work. However, the complicated overhead computations seriously degrade its performance in complexity reduction. This paper proposes a new prediction algorithm with less overhead operations. First, each N × N pixel block at the input of transform is resized to a N/2 × N/2 block. Then, this downsized block is decomposed into a mean value and a residual pixel block. Finally, the N × N 2-D DCT is computed from the mean value and this residual pixel block. Experimental results show that the proposed method reduces more redundant computations than the competing techniques and better real-time performance can be expected. This is particularly suitable for low-power processors with video sequences or great number of images to encode.