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.