3-DIMENSIONAL SUBBAND CODING OF AN IMAGE SEQUENCE BASED ON TEMPORALLYADAPTIVE DECOMPOSITION

We propose a temporally adaptive 3-D subband coding (3-D SEC) techniqu e to effectively exploit the temporal activities in the input image se quence. By using the rate-distortion (R-D) performance measure, we sho w the optimal number of temporal subbands can be easily determined. Th e base temporal subband, which yields much concentrated energy, is enc oded using the H.261-like motion-compensated discrete cosine transform (MC-DCT) technique. While in the higher temporal subbands, the two-di mensional (2-D) adaptive wavelet packet bases are employed to exploit the various energy distributions, due to the moving components. In enc oding the subbands, we employ adaptive scanning methods, followed by u niform step-size quantization with variable-length coding (VLC), and a coded/not-coded flag reduction technique based on the quadtree struct ure. From the simulation results, the proposed 3-D SEC provides about 0.29- to 3.14-dB PSNR gain over the H.261 technique and the temporally fixed 3-D SEC techniques at bit rates 300 to 512 Kbits/s. (C) 1996 So ciety of Photo-Optical Instrumentation Engineers.