@conference {
	title = {Motion-Compensated Wavelet Transform Coding for Full-Motion Color Video Signals},
	author = {Zhang, Ya-Qin. , Zafar, Sohail., Baras, John S.},
	year = {1991},
	month = {11/1991},
	abstract = {The discrete wavelet transform (DWT) has recently received much attention in the context of image~processing due to its flexibility in representing nonstationary image signals and its ability in ~adapting human visual characteristics. Its relationships to subband coding, Gabor transform, pyramid~structure and other intermediate spatial-frequency representation have been investigated [MALL89][BURT 89][VETT90]. Most of current research in DWT has been concentrated on still imagecoding in the area of data compression. In [BAAZ90], DWT was applied to decompose a sequence~of images and no coding results were reported. It is the purpose of this paper to apply DWT to~compress full motion color TV video signals using inter-frame motion-compensated coding, which,~to the best of our knowledge, has not been researched previously.

The compression scheme we implemented in our work is an interframe hybrid DPCM/DWT scheme~with a new motion compensation method. After motion compensation, the displaced frame difference(DFD) residue video signal is decomposed by wavelet representation and the wavelet pyramid~samples are uniformly quantized in each band. The quantization process takes advantage of human~visual characteristics and coefficients are weighted prior to the quantization. Motion vectors are~noiselessly coded. All quantities are entropy-coded adaptively prior to the transmission. The number~of samples in the wavelet representation is equal to the samples in the original frame as a consequence~of orthogonality of the decomposition.~

Two new block-based motion estimation schemes, namely: intra-frame and inter-frame predictive~motion estimation schemes, are used to find the displacement information prior to the wavelet~decomposition on the displace difference frame. In the proposed intra-frame predictive pattern~searching scheme (PPS), motion information in the neighboring blocks is exploited. This is especially~useful in estimating motion vectors of video signals which contain large homogeneous areas and~translations caused by object moving or camera panning. Therefore, motion vectors for these areas~are highly correlated. The purpose of intra-frame PPS is to take advantage of this correlation and~ hereby reduce the searching area. The proposed inter-frame predictive pattern searching scheme is based on the "inertia" property of moving object. The motion vectors of a block is estimated from~those of previous frames represented by an autoregressive model. The propose intra/inter PPS~Schemes not only significantly reduce the computational complexity of motion estimations, it also~gives more realistic motion vectors.

The proposed motion compensated DWT coding scheme is implemented in our Abekas-60 based~video compression testbed. The Abekas A-60 is basically a digital video recorder which allows a~real-time playback of 25 second recorded CCIR 601 digital video. The Abekas system is interfaced~with a SPARC workstation, where the compression software resides. By software simulation of the~compression/decompression techniques in the SPARC, we can reconstruct video segments to~compare with the original signal via a real-time play back. Therefore, we can evaluate compression performance, quality degradation, computational efficiency of different coding algorithms. The test~sequences "CAR" and "TOPGUN" we use are two full-motion color video sequences in CCIR 601~format with 720 by 480 per frame, 16 bits per pixel in YUV format (or 24 bits in RGB format) and~30 frames/60 fields per second. We measured the first-order entropy of the DFD signal, the entropy~of motion vectors, the reconstructed signal-to-noise ratio at a coding rate ranging from 1Mbps to 3~Mbps. Those results are also compared with the MPEG-like scheme which uses a motion~compensated hybrid DPCM/DCT scheme and is currently being standardized by the CCITT MPEG~committee. The subjective and comparative results suggest that the DWT can be successfully applied~to full-motion video compression and less "blocking effect" is observed compared to the DCT-based~block transform coding with about the same data rate and signal-to-noise ratio.},
	address = {Boston, Massachusetts},
	booktitle = {SPIE-Visual Communications and Image Processing {\textquoteright}91: Sixth in a Series},
	pages = {pp. 301-316}
}
