Image decoding method and device

Patent metadata

Field	Value
Publication number	US-12483705-B2
Application number	US-202318833579-A
Country	US
Kind code	B2
Filing date	Jan 10, 2023
Priority date	Jan 27, 2022
Publication date	Nov 25, 2025
Grant date	Nov 25, 2025

Abstract

An image decoding method performed by a decoding device according to the present disclosure comprises the steps of: deriving neighboring samples for sign prediction of a current block; deriving costs of sign combination candidates for transform coefficients of the current block on the basis of the neighboring samples; predicting signs of the transform coefficients from the sign combination candidates on the basis of the costs; deriving residual samples of the current block on the basis of the predicted signs; and generating a reconstructed picture on the basis of the residual samples.

First claim

What is claimed is:

1 . A method for an image decoding, the method performed by a decoding apparatus and comprising:
deriving neighboring samples for a sign prediction of a current block; deriving costs of sign combination candidates of transform coefficients of the current block based on the neighboring samples; predicting signs of the transform coefficients from the sign combination candidates based on the costs; deriving residual samples of the current block based on the predicted signs; and generating a reconstructed picture based on the residual samples.

2 . The method of claim 1 , wherein the neighboring samples are derived based on a size of the current block.

3 . The method of claim 2 , wherein, when a width of the current block is greater than a height of the current block, a cost of a specific sign combination candidate is derived based on upper neighboring samples of the current block, predicted samples of a top row of the current block, and hypothesis residual samples for the specific sign combination candidate of the top row.

4 . The method of claim 3 , wherein, when the width of the current block is greater than the height of the current block, the cost of the specific sign combination candidate is derived based on the following equation,

cost
=

∑

x
=
o

w
-
1

⁢

❘
"\[LeftBracketingBar]"

(

-

R

x
,

-
2

+

2
⁢

R

x
,

-
1

-

P

x
,
0

)

-

r

x
,
0

❘
"\[RightBracketingBar]"

where, w represents the width of the current block, Rx,- 2 represents a upper neighboring sample at (x,−2) position, R x,−1 represents a upper neighboring sample at (x,−1) position, P x,0 represents a predicted sample at position (x,0), and r x,0 represents a hypothetical residual sample at location (x,0).

5 . The method of claim 2 , wherein, when a height of the current block is greater than a width of the current block, a cost of a specific sign combination candidate is derived based on left neighboring samples of the current block, predicted samples in a left column of the current block, and hypothesis residual samples for the specific sign combination candidate in the left column.

6 . The method of claim 5 , wherein, when the height of the current block is greater than the width of the current block, the cost of the specific sign combination candidate is derived based on the following equation,

cost
=

∑

y
=
o

h
-
1

⁢

❘
"\[LeftBracketingBar]"

(

-

R

-
2

,
y

+

2
⁢

R

-
1

,
y

-

P

0
,
y

)

-

r

0
,
y

❘
"\[RightBracketingBar]"

where, h represents the height of the current block, R −2,y represents a left neighboring sample at (−2,y) location, R −1,y represents a left neighboring sample at (−1,y) location, P 0,y represents a predicted sample at (0,y) location, and r 0,y represents a hypothetical residual sample at location (0,y).

7 . The method of claim 2 , wherein, when a width of the current block is greater than a height of the current block, a cost of a specific sign combination candidate is derived based on upper neighboring samples of the current block, predicted samples of a top row of the current block, and hypothesis residual samples for the specific sign combination candidate of the top row, and
wherein the upper neighboring samples, the predicted samples, and the hypothesis residual samples are selected in numbers equal to the height per row.

Assignees

• Lg Electronics Inc

Inventors

• Yoo Sunmi
• Nam Junghak
• Choi Jungah

Classifications

• H04N19/176 Primary

  the region being a block, e.g. a macroblock · CPC title

• H04N19/105

  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 title

• H04N19/61

  in combination with predictive coding · CPC title

• H04N19/593

  involving spatial prediction techniques · CPC title

• H04N19/18

  the unit being a set of transform coefficients · CPC title