Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1991-02-20
1993-06-08
Groody, James J.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358135, 358136, H04N 712, H04N 713
Patent
active
052184358
ABSTRACT:
Image quality is improved in high definition television using multi-scale representation of motion compensated residuals. The bandwidths of the subband filters vary with the frequency band and the total number of coefficients in the multi-scale-represented frames is equal to the number of values in the residual. Image initialization in the receivers is achieved using original image leakage, but the leakage factor is varied for different frequency subbands. To free up channel capacity at scene changes, a global (i.e., substantially frame-wide) decision is made as to whether to motion compensate a particular frame. To avoid the unattractive ghost of the previous scene persisting for a short time in a new scene, the motion estimator makes a decision on a block-by-block basis whether to use the original image or the residual. Chrominance resolution is improved by encoding all of the subbands of the chroma residuals, instead of just the low subbands. The chroma residuals are encoded at relatively coarser quantization than the luma residual, but when the energy of the luma residual is low (as, e.g. may occur when there is little motion), chroma quantization is improved, by making an overall (both chroma and luma) reduction in quantization step size. Runlength-amplitude representation and statistical coding are used. Runlength-amplitude representation is applied to entire subbands, and, preferably, different codebooks are used in statistically coding different subbands, to take advantage of the different statistics in the different subbands. The quantization coarseness is adaptively varied based on a computation of the number of bits necessary to statistically code a particular frame, thus guaranteeing for each frame exactly (or approximately, if a small buffer is provided in the decoder) the number of bits available in the channel.
REFERENCES:
patent: 4546386 (1985-10-01), Matsumoto et al.
patent: 4817182 (1989-03-01), Adelson et al.
patent: 4821119 (1989-04-01), Gharavi
patent: 4829378 (1989-05-01), LeGall
patent: 4838685 (1989-06-01), Martinez et al.
patent: 4918524 (1990-04-01), Ansari et al.
patent: 4941042 (1990-06-01), Martens
patent: 4943855 (1990-07-01), Bheda et al.
patent: 4969040 (1990-11-01), Gharavi
patent: 5006929 (1991-04-01), Barbero et al.
patent: 5067015 (1991-11-01), Combridge et al.
Adelson et al., "Orthogonal pyramid transform for image coding," SPIE vol. 845 Visual Communications and Image Processing II, pp. 50-58 (1987).
Burt et al., "The Laplacian Pyramid as a Compact Image Code," IEEE Transactions on Communications, vol. Com-31, No. 4, pp. 532-540 (Apr., 1983).
Kovacevic et al., "Image Coding with Windowed Modulated Filter Banks," pp. 1949-1952 (1989).
Lim, Two Dimensional Signal and Image Processing, pp. 497-507, 632-640, 642-656 (1990).
Woods et al., "Subband Coding of Images", IEEE Transactions on Acoustics, Speech, and Signal Processing, vol. ASSP-34, No. 5, pp. 1278-1288 (Oct., 1986).
Lim Jae S.
Monta Peter A.
Groody James J.
Lee Michael H.
Massachusetts Institute of Technology
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