Method of intra predicting a block of a picture

1. A computer-implemented method of intra predicting a block of a picture, the method comprising:

for a sample of the block:

obtaining a predicted sample value from one or more reference sample values by performing intra-prediction using a DC intra-prediction mode;

multiplying the predicted sample value by a sample weighting factor to produce a weighted predicted sample value;

adding an additional value to the weighted predicted sample value to produce a non-normalized predicted sample value; and

normalizing the non-normalized predicted sample value by an arithmetic right shift;

wherein the sample weighting factor is ((2<<p)−wL−wT),

wherein

p is a parameter of the sample weighting factor,

wL is a horizontal weighting factor, and

wT is a vertical weighting factor.

2. The method of claim 1 , further comprising:

calculating the additional value using a PLANAR intra prediction mode.

3. The method of claim 1 , wherein the sample weighting factor is (64−wL−wT).

4. The method of claim 1 , wherein the additional value is a sum of one or more summands, the one or more summands including a summand depending on at least one of the reference sample values.

5. The method of claim 4 , wherein the summand is wL×R −1,y +wT×R x,−1 , R x,−1 and R −1,y representing values of nearest reference samples located above and to the left of a predicted sample, respectively.

6. The method of claim 1 , wherein the horizontal weighting factor wL or the vertical weighting factor wT is a power of two.

7. The method of claim 1 , wherein

the horizontal weighting factor wL=(2<<(p−1))>>((x<<1)>>nScale), wherein x is a horizontal coordinate of the sample,

the vertical weighting factor wT=(2<<(p−1))>>((y<<1)>>nScale), wherein y is a vertical coordinate of the sample, and

nScale is a scale parameter.

8. The method of claim 7 , further comprising: deriving the scale parameter nScale from a size of the block.

9. The method of claim 7 , wherein the scale parameter nScale is ((Log 2(nTbW)+Log 2(nTbH)−2)>>2) wherein nTbW is a width of the block and nTbH is a height of the block.

10. The method of claim 1 , wherein normalizing the non-normalized predicted sample value comprises:

( wL×R −1,y +wT×R x,−1 +(64− wL−wT )× P ( x,y )+32)>>6

wherein

P(x, y) represents the predicted sample value,

(64−wL−wT) represents the sample weighting factor,

(64−wL−wT)×P(x, y) represents the weighted predicted sample value,

wL×R −1,y +wT×R x,−1 represents the additional value,

wL×R −1,y +wT×R x,−1 +(64−wL−wT)×P(x, y) represents the non-normalized predicted sample value,

>> represents the arithmetic right shift,

R x,−1 , R −1,y represent values of nearest reference samples located above and to the left of a predicted sample, respectively,

wL is the horizontal weighting factor, and

wT is the vertical weighting factor.

11. A method of encoding or decoding a picture, comprising:

obtaining normalized predicted sample values by performing the method according to claim 1 ; and

adding residual values to the normalized predicted sample values to produce reconstructed sample values.

12. A computer-implemented method of intra predicting a first block and a second block of a picture, the method comprising:

for a sample of the first block and for a sample of the second block:

obtaining a predicted sample value from one or more reference sample values by performing intra-prediction using an intra-prediction mode;

multiplying the predicted sample value by a sample weighting factor to produce a weighted predicted sample value;

adding an additional value to the weighted predicted sample value to produce a non-normalized predicted sample value; and

normalizing the non-normalized predicted sample value by an arithmetic right shift;

wherein

the sample weighting factor is ((2<<p)−wL−wT),

p is a parameter of the sample weighting factor,

wL is a horizontal weighting factor, and

wT is a vertical weighting factor,

wherein the intra-prediction mode used for obtaining the predicted sample value for the first block is a DC intra-prediction mode, and the intra-prediction mode used for obtaining the predicted sample value for the second block is a PLANAR intra-prediction mode.

13. A device for encoding or decoding a picture, the device comprising: a processing circuitry configured to perform the method of claim 1 .

14. A non-transitory computer-readable medium having instructions stored therein, which when executed by a computer device, cause the computer device to perform the method of claim 1 .

15. A device for intra predicting a block of a picture, the device comprising:

one or more processors;

a non-transitory computer-readable storage medium coupled to the one or more processors to store instructions, which when executed by the one or more processors, cause the one or more processors to:

for a sample of the block:

obtain a predicted sample value from one or more reference sample values by performing intra-prediction using a DC intra-prediction mode;

multiply the predicted sample value by a sample weighting factor to produce a weighted predicted sample value;

add an additional value to the weighted predicted sample value to produce a non-normalized predicted sample value; and

normalize the non-normalized predicted sample value by an arithmetic right shift;

wherein the sample weighting factor is ((2<<p)−wL−wT),

wherein

p is a parameter of the sample weighting factor,

wL is a horizontal weighting factor, and

wT is a vertical weighting factor.

16. The device of claim 15 , wherein the sample weighting factor is (64−wL−wT).

17. The device of claim 15 , wherein the additional value is a sum of one or more summands, the one or more summands including a summand depending on at least one of the reference sample values, and wherein the summand is wL×R −1,y +wT×R x,−1 , R x,−1 and R −1,y representing values of nearest reference samples located above and to the left of a predicted sample, respectively.

18. The device of claim 15 , wherein the horizontal weighting factor wL or the vertical weighting factor wT is a power of two.

19. The device of claim 15 , wherein normalizing the non-normalized predicted sample value comprises:

( wL×R −1,y +wT×R x,−1 +(64− wL−wT )× P ( x,y )+32)>>6

wherein

P(x, y) represents the predicted sample value,

(64−wL−wT) represents the sample weighting factor,

(64−wL−wT)×P(x, y) represents the weighted predicted sample value,

wL×R −1,y +wT×R x,−1 represents the additional value,

wL×R −1,y +wT×R x,−1 +(64−wL−wT)×P(x, y) represents the non-normalized predicted sample value,

>> represents the arithmetic right shift,

R x,−1 , R −1,y represent values of nearest reference samples located above and to the left of a predicted sample, respectively,

wL is the horizontal weighting factor, and

wT is the vertical weighting factor.