Three‐dimensional subband coding of an image sequence based on temporally adaptive decomposition

Abstract

We propose a temporally adaptive 3-D subband coding (3-D SBC) technique to effectively exploit the temporal activities in the input image sequence. By using the rate-distortion (R-D) performance measure, we show the optimal number of temporal subbands can be easily determined. The base temporal subband, which yields much concentrated energy, is encoded using the H.261-like motion-compensated discrete cosine transform (MC-DCT) technique. While in the higher temporal subbands, the two-dimensional (2-D) adaptive wavelet packet bases are employed to exploit the various energy distributions, due to the moving components. In encoding the subbands, we employ adaptive scanning methods, followed by uniform step-size quantization with variablelength coding (VLC), and a coded/not-coded flag reduction technique based on the quadtree structure. From the simulation results, the proposed 3-D SBC provides about 0.29-to 3.14-dB PSNR gain over the H.261 technique and the temporally fixed 3-D SBC techniques at bit rates 300 to 512 Kbits/s.

A Temporally Adaptive Layered Image Coding Technique Based on the 3D SBC for ATM Networks

“…On the contrary, small frame skip ratio yields a low spatial quality, but high temporal Instead of the H.261 technique for the enhancement resolution. Hence, it is believed that by varying the tempolayer, we employ the temporally adaptive 3D SBC techral skip ratio M, we can achieve a trade-off between the nique, proposed by Kim [8], with modifications. In the spatial quality and temporal resolutions in the base layer proposed technique, the temporal adaptivity is exploited decoded image.…”

“…The scanned data are then encoded in variable-length codes using the 2D Huffman tables. Refer to [8] for the details employed in our approach. However, notice that, since the error image is encoded by the enhancement layer 3D SBC coder, the H.261-like MC-DCT technique employed in [8] is replaced with the spatial subband coding technique as a coding technique for the base temporal subband, in the proposed approach.…”

“…In order to alleviate the effects of have been made to improve the performance of the 3D the cell loss, Ghanbari proposed the twin-H.261 technique SBC [8,[12][13][14]. Among them, recently proposed tempo- [4], in which the H.261 with leaky prediction (leaky facrally adaptive 3D SBC technique [8] is reported to provide tor ϭ 0.9) is employed for encoding the error image of the better performance than the H.261 technique, since it can enhancement layer. However, it is worthy to note that the effectively take into account the temporal motion activity.…”

“…But the enhancement layer is which the number of reference frames and their intervals transmitted with low error resilience capability, resulting were adjusted, according to the temporal activity of the input image. Also, Kim [8] proposed the temporally adap-by adjusting the frame rate, according to the temporal statistics of the input image. Specific description on the frame rate control shall be discussed subsequently.…”

“…Howproper partitioning schemes. The base layer for providing ever, it is worthy to note that the image sequence exhibits the basic resolution is encoded by itself, while the enhancedifferent characteristics along the temporal domain [7][8][9]. ment layer is encoded with full resolution, with respect to Moreover, due to the temporal masking effect, the percepthe base layer.…”