# US 10,123,048 B2 · Method of filter control for block-based adaptive loop filtering > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,123,048 B2 - Document ID: US10123048B2 - Status: Granted - Kind: B2 - Application number: 15/034,125 - Filed: 2014-11-13 - Published: 2016-09-08 - Granted: 2018-11-06 - Earliest claimed: 2013-11-15 - Assignees: Mediatek Inc. - Applicants: MediaTek Inc. - Inventors: Ching-Yeh Chen; Chia-Yang Tsai; Yu-Wen Huang - Web page: https://patentgrep.com/patent/US10123048B2 ## CPC - H04N 19/82: involving filtering within a prediction loop - H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635) - H04N 19/119: Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks - H04N 19/14: Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence) - H04N 19/172: the region being a picture, frame or field - H04N 19/176: the region being a block, e.g. a macroblock - H04N 19/18: the unit being a set of transform coefficients - H04N 19/182: the unit being a pixel - 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) - H04N 19/68: involving the insertion of resynchronisation markers into the bitstream - H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract A method of adaptive loop filtering with implicit sample-based On/Off control for reconstructed video to improve the performance is disclosed. In one embodiment, each pixel of the video data associated with the reconstructed current image unit is classified into a first group and a second group. Adaptive Loop Filter (ALF) is then applied to these pixels belonging to the first group. For pixels in the second group, ALF is not applied. The image unit may correspond to one coding tree block (CTB) or one coding tree unit (CTU). Various classification means for classifying each pixel into a first group or a second group have also been disclosed. The adaptive loop filtering with implicit sample-based On/Off control may also be used as an additional mode in a system supporting block-based On/Off control. ## Claims ### Claim 1 A method of adaptive loop filtering for reconstructed video in a video encoding system or video decoding system, wherein each picture of the reconstructed video is partitioned into image units, the method comprising: receiving video data associated with a reconstructed current image unit; and applying Implicit Sample-based On/Off adaptive loop filter (ALF) to the video data, wherein said applying Implicit Sample-based On/Off ALF comprises: classifying each pixel of the video data associated with the reconstructed current image unit into a first group or a second group based on reconstructed video commonly available to both an encoder side and a decoder side; applying adaptive loop filter to the pixels of the video data associated with the reconstructed current image unit belonging to the first group; and skipping the adaptive loop filter for the pixels of the video data associated with the reconstructed current image unit belonging to the second group; and for the video encoding system, selecting an ALF mode for the reconstructed current image unit from a filter mode group consisting of ALF-Off mode, ALF-On mode, and ALF Implicit On/Off mode, wherein said applying Implicit Sample-based On/Off ALF is performed only if the ALF Implicit On/Off mode is selected; if the ALF-Off mode is selected, skipping the adaptive loop filter for all pixels of the video data associated with the reconstructed current image unit; if the ALF-On mode is selected, applying the adaptive loop filter to all samples in the video data associated with the reconstructed current image unit; and incorporating one or more syntax elements in a coded bitstream to signal the ALF mode selected for the reconstructed current image unit. ### Claim 2 (depends on 1) The method of claim 1, wherein the image unit corresponds to one coding tree block (CTB) or one coding tree unit (CTU). ### Claim 3 (depends on 1) The method of claim 1, wherein said classifying each pixel of the video data associated with the reconstructed current image unit applies a classification process to the video data associated with the reconstructed current image unit, wherein the classification process is selected from a filter group consisting of linear filtering, non-linear filtering, edge detection, difference or similarity between to-be-classified pixel and neighboring pixels, intensity, edge offset (EO) classifications, band offset (BO) classification, magnitude of residual, and any combination thereof. ### Claim 4 (depends on 1) The method of claim 1, wherein said classifying each pixel of the video data associated with the reconstructed current image unit applies a classification process to the video data associated with the reconstructed current image unit, wherein the classification process is selected from a filter group adaptively at a sequence level, picture level, slice level or block level of a bitstream. ### Claim 5 (depends on 4) The method of claim 4, wherein the block level corresponds to a coding tree block (CTB) level or a coding tree unit (CTU) level. ### Claim 6 (depends on 1) The method of claim 1, wherein the video data associated with the reconstructed current image unit corresponds to the reconstructed current image unit, a first output data resulted from applying deblocking process to the reconstructed current image unit, or a second output data resulted from said applying deblocking process and sample adaptive offset (SAO) process to the reconstructed current image unit. ### Claim 7 (depends on 1) The method of claim 1, further comprising incorporating side information associated with said classifying each pixel of the video data associated with the reconstructed current image unit in at a sequence level, picture level, slice level or block level of a bitstream. ### Claim 8 (depends on 1) The method of claim 1, wherein side information associated with said classifying each pixel of the video data associated with the reconstructed current image unit is determined implicitly. ### Claim 9 (depends on 1) The method of claim 1, wherein said one or more syntax elements is incorporated in a sequence level, picture level, slice level or block level of the coded bitstream to signal the ALF mode. ### Claim 10 (depends on 1) The method of claim 1, for the video decoding system, further comprising: parsing the ALF mode for the reconstructed current image unit from the coded bitstream, wherein the ALF mode belongs to the filter mode group and said applying Implicit Sample-based On/Off ALF is performed only if the ALF Implicit On/Off mode is selected; if the ALF-Off mode is selected, skipping the adaptive loop filter for all pixels of the video data associated with the reconstructed current image unit; and if the ALF-On mode is selected, applying the adaptive loop filter to all samples in the video data associated with the reconstructed current image unit. ### Claim 11 (depends on 10) The method of claim 10, wherein the ALF mode is parsed from a sequence level, picture level, slice level or block level of the coded bitstream. ### Claim 12 An apparatus for applying adaptive loop filtering for reconstructed video in a video encoding system or video decoding system, wherein each picture of the reconstructed video is partitioned into image units, the apparatus comprising one or more electronic circuits configured to: receive video data associated with a reconstructed current image unit from storage or from a processor; and apply Implicit Sample-based On/Off adaptive loop filter (ALF) to the video data, wherein said apply Implicit Sample-based On/Off ALF comprises: classifying each pixel of the video data associated with the reconstructed current image unit into a first group or a second group based on reconstructed video commonly available to both an encoder side and a decoder side; applying adaptive loop filter to the pixels of the video data associated with the reconstructed current image unit belonging to the first group; and skipping the adaptive loop filter for the pixels of the video data associated with the reconstructed current image unit belonging to the second group; and for the video encoding system, select an ALF mode for the reconstructed current image unit from a filter mode group consisting of ALF-Off mode, ALF-On mode, and ALF Implicit On/Off mode, wherein said apply Implicit Sample-based On/Off ALF is performed only if the ALF Implicit On/Off mode is selected; if the ALF-Off mode is selected, skip the adaptive loop filter for all pixels of the video data associated with the reconstructed current image unit; if the ALF-On mode is selected, apply the adaptive loop filter to all samples in the video data associated with the reconstructed current image unit; and incorporate one or more syntax elements in a coded bitstream to signal the ALF mode selected for the reconstructed current image unit. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein said classifying each pixel of the video data associated with the reconstructed current image unit applies a classification process to the video data associated with the reconstructed current image unit, wherein the classification process is selected from a filter group consisting of linear filtering, non-linear filtering, edge detection, difference or similarity between to-be-classified pixel and neighboring pixels, intensity, edge offset (EO) classifications, band offset (BO) classification, magnitude of residual, and any combination thereof. ### Claim 14 (depends on 12) The apparatus of claim 12, for the video decoding system, the one or more electronic circuits being further configured to: parse the ALF mode for the reconstructed current image unit from the coded bitstream, wherein the ALF mode belongs to the filter mode group and said apply Implicit Sample-based On/Off ALF is performed only if the ALF Implicit On/Off mode is selected; if the ALF-Off mode is selected, skip the adaptive loop filter for all pixels of the video data associated with the reconstructed current image unit; and if the ALF-On mode is selected, apply the adaptive loop filter to all samples in the video data associated with the reconstructed current image unit. ### Claim 15 A method of adaptive loop filtering for reconstructed video in a video encoding system or video decoding system, wherein each picture of the reconstructed video is partitioned into image units, the method comprising: receiving video data associated with a reconstructed current image unit; and applying Implicit Sample-based On/Off adaptive loop filter (ALF) to the video data, wherein said applying Implicit Sample-based On/Off ALF comprises: classifying each pixel of the video data associated with the reconstructed current image unit into a first group or a second group based on reconstructed video commonly available to both an encoder side and a decoder side; applying adaptive loop filter to the pixels of the video data associated with the reconstructed current image unit belonging to the first group; and skipping the adaptive loop filter for the pixels of the video data associated with the reconstructed current image unit belonging to the second group; and for the video decoding system, parsing an ALF mode for the reconstructed current image unit from a coded bitstream, wherein the ALF mode belongs to a filter mode group consisting of ALF-Off mode, ALF-On mode, and ALF Implicit On/Off mode and said applying Implicit Sample-based On/Off ALF is performed only if the ALF Implicit On/Off mode is selected; if the ALF-Off mode is selected, skipping the adaptive loop filter for all pixels of the video data associated with the reconstructed current image unit; and if the ALF-On mode is selected, applying the adaptive loop filter to all samples in the video data associated with the reconstructed current image unit.