In this paper we address the problem of coding images and video at very low bitrates using conventional hybrid differential pulse code modulation/discrete cosine transform (DPCM/DCT) coding schemes with reduced blocking artifacts. To this end, optimal block-overlapping synthesis filterbanks (block-overlapping inverse transform kernels) with minimum least-squares reconstruction error properties are derived which replace the conventional inverse DCT if only a few DCT coefficients are transmitted to the receiver. Results show that the proposed inverse block-overlapping transforms can significantly outperform the conventional inverse DCT both in terms of objective and subjective quality measures.
['Thomas Sikora', 'Hui Li']
Optimal block-overlapping synthesis transforms for coding images and video at very low bitrates