IP Library › Granted Patent US 12689760
Granted Patent B2
US 12689760 · App. 18/892,820 · Granted Jul 21, 2026

Method and apparatus for image coding/decoding

Inventors: Sung Chang Lim (Daejeon-si, KR); Hui Yong Kim (Daejeon-si, KR); Jin Ho Lee (Daejeon, KR); Jin Soo Choi (Daejeon, KR); Jin Woong Kim (Daejeon, KR)
Assignee: Electronics and Telecommunications Research Institute
H04N19/52
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Quick Facts
Patent No.
US 12689760
App. No.
18/892,820
Granted
Jul 21, 2026
Kind
B2
Abstract

A method for decoding an image according to the present invention comprises the steps of: decoding a residual block by quantizing and inverse transforming an entropy-decoded residual block; generating a prediction block via motion compensation; and decoding an image by adding the decoded residual block to the prediction block, wherein on the basis of the maximum number of motion vector candidates of the motion vector candidate list related to the prediction block, a motion vector candidate list is adjusted by adding a particular motion vector candidate or by discarding a portion from among the motion vector candidates, and in the prediction block generation step, a prediction motion vector of the prediction block is determined on the basis of the adjusted motion vector candidate list. Accordingly, the complexity of arithmetic operations is reduced during encoding/decoding of an image.

Claims (28)

1 . An image decoding method comprising:

configuring a motion vector candidate list;

modifying the motion vector candidate list based on a number of motion vector candidates in the motion vector candidate list; and

determining a prediction motion vector based on the modified motion vector candidate list,

wherein the motion vector candidate list includes at least one of a spatial motion vector candidate, a temporal motion vector candidate and a specific motion vector candidate,

wherein the temporal motion vector candidate is generated by performing scaling when a distance between a current picture and a reference picture of the current block is different from a distance between a collocated picture and a reference picture of a collocated block,

wherein the configuring the motion vector candidate list comprises;

deriving the spatial motion vector candidate,

deriving the temporal motion vector candidate, and

adding at least one of the derived spatial motion vector candidate and the derived temporal motion vector candidate to the motion vector candidate list,

wherein an operation of removing the same motion vector candidate is carried out only on spatial motion vector candidates and the temporal motion vector candidate is derived except when two derived spatial motion vector candidates are present and different from each other,

wherein when the number of motion vector candidates in the motion vector candidate list is smaller than a maximum number of motion vector candidates, the modifying the motion vector candidate list includes repeatedly adding the specific motion vector candidate until the number of motion vector candidates in the motion vector candidate list reaches the maximum number of motion vector candidates, and

wherein the maximum number of motion vector candidates is 2 and when no motion vector candidate is present in the motion vector candidate list, two specific motion vector candidates are added to the motion vector candidate list.

2 . The image decoding apparatus of claim 1 , wherein the specific motion vector candidate is a (0,0) motion vector.

3 . An image encoding method comprising:

generating a prediction block by performing an inter prediction; and

performing an entropy encoding of a residual block corresponding to a difference between a current block and the prediction block predicted by the inter prediction,

wherein a prediction motion vector corresponding to the prediction block is included in a motion vector candidate list,

wherein the motion vector candidate list includes at least one of a spatial motion vector candidate, a temporal motion vector candidate and a specific motion vector candidate,

wherein the temporal motion vector candidate is generated by performing scaling when a distance between a current picture and a reference picture of the current block is different from a distance between a collocated picture and a reference picture of a collocated block,

wherein the motion vector candidate list is configured by:

deriving the spatial motion vector candidate,

deriving the temporal motion vector candidate, and

adding at least one of the derived spatial motion vector candidate and the derived temporal motion vector candidate to the motion vector candidate list,

wherein an operation of removing the same motion vector candidate is carried out only on spatial motion vector candidates and the temporal motion vector candidate is derived except when two derived spatial motion vector candidates are present and different from each other,

wherein when the number of motion vector candidates in the motion vector candidate list is smaller than a maximum number of motion vector candidates, the modifying the motion vector candidate list includes repeatedly adding the specific motion vector candidate until the number of motion vector candidates in the motion vector candidate list reaches the maximum number of motion vector candidates, and

wherein the maximum number of motion vector candidates is 2 and when no motion vector candidate is present in the motion vector candidate list, two specific motion vector candidates are added to the motion vector candidate list.

4 . The image encoding method of claim 3 , wherein the specific motion vector candidate is a (0,0) motion vector.