US 12,341,958 B2
Combined loop filtering
Jacob Ström, Stockholm (SE); and Per Wennersten, Årsta (SE)
Assigned to TELEFONAKTIEBOLAGET LM ERICSSON (PUBL), Stockholm (SE)
Appl. No. 18/277,974
Filed by Telefonaktiebolaget LM Ericsson (publ), Stockholm (SE)
PCT Filed Jan. 31, 2022, PCT No. PCT/SE2022/050100
§ 371(c)(1), (2) Date Aug. 18, 2023,
PCT Pub. No. WO2022/211693, PCT Pub. Date Oct. 6, 2022.
Claims priority of provisional application 63/167,803, filed on Mar. 30, 2021.
Prior Publication US 2024/0155119 A1, May 9, 2024
Int. Cl. H04N 19/117 (2014.01); H04N 19/167 (2014.01); H04N 19/196 (2014.01); H04N 19/176 (2014.01)
CPC H04N 19/117 (2014.11) [H04N 19/167 (2014.11); H04N 19/196 (2014.11); H04N 19/176 (2014.11)] 12 Claims
OG exemplary drawing
 
1. A method for parameter estimation in loop filtering for encoding one or more images, the method comprising:
filtering, with a first filter, input samples I(x,y) to generate a first filtered output Ifirst(x,y)=I(x,y)+ΔIfirst(x,y), wherein ΔIfirst(x,y) represents a first offset to the input samples I(x,y);
estimating parameters for a second filter based at least in part on the first filtered output Ifirst(x,y), the input samples I(x,y), and original samples Iorig(x,y), wherein the second filter comprises a sample adaptive offset (SAO) filter, wherein estimating parameters for the second filter comprises:
for each sample in the input samples I(x,y), identifying a class associated with the sample, wherein identifying a class associated with the sample results in a set of classes with each class in the set of classes associated with zero or more positions (xi,yi) corresponding to the samples I(xi,yi) associated with the class;
for each class, (1) calculating a deviation between the first filtered output Ifirst(xi,yi) and the original samples Iorig(xi,yi) for each position (xi,yi) associated with the class; and (2) determining an offset based on the deviation calculated;
filtering, with the second filter, input samples I(x,y) to generate a second filtered output Isecond(x,y)=I(x,y)+ΔIsecond(x,y), wherein ΔIsecond(x,y) represents a second offset to the input samples I(x,y) and filtering, with the second filter, is based at least in part on the parameters estimated for the second filter; and
generating a combined output ICOMB (x,y)=I(x,y)+ΔIfirst(x,y)+ΔIsecond(x,y).