Adaptive filtering based upon boundary strength

• US 9,872,024 B2
• Filed: 08/07/2017
• Issued: 01/16/2018
• Est. Priority Date: 09/14/2001
• Status: Expired due to Term

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Sun, Shijun, Lei, Shawmin, Katata, Hiroyuki
• Primary Examiner(s): LEE, Y YOUNG
• Application Number:
  US15/670,250
• Publication Number:
  US 20170339406A1
• Time in Patent Office: 162 Days
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/117 Filters, e.g. for pre-processing or post-processing sub-band filter banks H04N19/635
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/137 Motion inside a coding unit, e.g. average field, frame or block difference
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• 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 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/167 Position within a video image, e.g. region of interest [ROI]
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/197 including determination of the initial value of an encoding parameter H04N19/56 takes precedence
• CPC Class Codes: H04N 19/43 Hardware specially adapted for motion estimation or compensation
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/527 Global motion vector estimation
• CPC Class Codes: H04N 19/573 Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction
• CPC Class Codes: H04N 19/58 Motion compensation with long-term prediction, i.e. the reference frame for a current frame not being the temporally closest one H04N19/23 takes precedence
• CPC Class Codes: H04N 19/60 : using transform coding
• CPC Class Codes: H04N 19/61 : in combination with predictive coding
• CPC Class Codes: H04N 19/615 : using motion compensated temporal filtering [MCTF]
• CPC Class Codes: H04N 19/82 : involving filtering within a prediction loop
• CPC Class Codes: H04N 19/85 : using pre-processing or post-processing specially adapted for video compression
• CPC Class Codes: H04N 19/86 : involving reduction of coding artifacts, e.g. of blockiness

Abstract

An image decoding apparatus that includes a motion compensation prediction circuit configured to conduct motion compensation prediction for each of blocks to be decoded by using the reconstructed image, an inverse transformation circuit configured to conduct inverse orthogonal transformation for the data of the blocks to be decoded, and a determination circuit configured to determine a filtering strength and whether or not to conduct filtering, with respect to each of the boundaries. In addition, the determining circuit is configured to determine filtering is conducted when at least one of the two adjacent blocks is intra-coded, and filtering is not conducted when both of the two adjacent blocks are not intra-coded, a non-zero transformation coefficient is not coded in both of the two adjacent blocks, the two adjacent blocks are predicted by the same reference frame, and an absolute value of a difference between motion vectors of the two adjacent blocks is smaller than a specified threshold value.

Claims

1. An image decoding apparatus for filtering a boundary between two adjacent blocks in a reconstructed image, comprising:

a motion compensation prediction means for predicting a block to be decoded by using a previously reconstructed image as a reference image;

an inverse quantization means for performing inverse quantization of a block of transformed and quantized coefficients;

an inverse transformation means for conducting inverse transformation of the block of inverse quantized coefficients;

an image reconstruction means for reconstructing an image using the motion compensation predicted block and the inverse transformed block; and

a deblock filter for deblock filtering the reconstructed image;

wherein the deblock filter includes a determination means for determining whether or not to conduct filtering at a boundary between two adjacent blocks in the reconstructed image, where;

(1) filtering is conducted when at least one of the two adjacent blocks is intra-coded, and

(2) filtering is not conducted when both of the two adjacent blocks are not intra-coded, a non-zero transformation coefficient is not coded in both of the two adjacent blocks, the two adjacent blocks are predicted by a same reference frame, and an absolute value of a difference between motion vectors of the two adjacent blocks is smaller than a specified threshold value,

wherein the filtering modifies the pixel values at the boundary between the two adjacent blocks in the reconstructed image when at least one of the two adjacent blocks is intra-coded.