Inter-frame wavelet transform coder for color video compression

• US 5,495,292 A
• Filed: 09/03/1993
• Issued: 02/27/1996
• Est. Priority Date: 09/03/1993
• Status: Expired due to Term

• Current Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Original Assignee: GTE Laboratories Incorporated (Lumen Technologies, Inc.)
• Inventors: Zafar, Sohail, Zhang, Ya-Qin
• Primary Examiner(s): Chin, Tommy P.
• Assistant Examiner(s): LIN, BRYAN T
• Application Number:
  US08/117,518
• Time in Patent Office: 907 Days
• Field of Search: 348/398, 348/397, 348/408, 348/402, 348/407, 348/416, 348/415, 348/409, 348/390, 348/384
• US Class Current: 375/240.02
• CPC Class Codes: H04N 19/10 using adaptive coding
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/147 according to rate distortion criteria rate-distortion as a criterion for motion estimation H04N19/567
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/187 the unit being a scalable video layer
• CPC Class Codes: H04N 19/19 using optimisation based on Lagrange multipliers
• CPC Class Codes: H04N 19/48 using compressed domain processing techniques other than decoding, e.g. modification of transform coefficients, variable length coding [VLC] data or run-length data motion estimation in a transform domain H04N19/547; processing of decoded motion vectors H04N19/513
• CPC Class Codes: H04N 19/53 Multi-resolution motion estimation; Hierarchical motion estimation
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/619 the transform being operated outside the prediction loop
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets

Abstract

A video coding scheme based on wavelet representation performs motion compensation in the wavelet domain rather than spatial domain. This inter-frame wavelet transform coding scheme preferably uses a variable-size multi-resolution motion compensation (MRMC) prediction scheme. The MRMC scheme produces displaced residual wavelets (DRWs). An optimal bit allocation algorithm produces a bit map for each DRW, and each DRW is then adaptively quantized with its respective bit map. Each quantized DRW is then coded into a bit stream.

Claims

1. A method of coding a video signal frame f(t), comprising the steps of:

deriving a wavelet representation of a signal defined by a plurality of wavelets each corresponding to a subframe having a resolution;

estimating motion vectors for each of said plurality of wavelets to produce a set of displaced residual wavelets;

optimally assigning a given number of bits to each of said displaced residual wavelets to produce a respective bit map for each of aid displaced residual wavelets;

adaptively quantizing each of said displaced residual wavelets using its respective bit map; and

coding each quantized displaced residual wavelet into a bit stream

wherein the step of estimating motion vectors includes the steps of;

dividing each subframe into a see of blocks defining a grid, wherein the size of each block is based on the associated resolution of the respective subframe;

calculating a motion vector, relative to a previous frame, for each block of a lowest resolution subframe;

calculating motion vectors of each block of other subframes, comprising the steps of scaling a motion vector corresponding to a respective block of said lowest resolution subframe, and calculating a motion vector, relative to the previous frame, for a block under motion compensation using the scaled motion vector.