Method of depth intra prediction using depth map modelling

1. A method of Intra coding for a depth block in a three-dimensional video coding system, the method comprising:

receiving input data associated with a current depth block, wherein the current depth block is partitioned into one or more segments;

receiving reconstructed neighboring depth samples of the current depth block;

deriving a prediction value for each segment based on reconstructed neighboring depth samples, wherein the reconstructed neighboring depth samples for at least one segment comprise at least one reconstructed sample from an extended top neighboring row or an extended left neighboring column, the extended top neighboring row includes at least one extended top-row reconstructed depth sample located adjacent to top side of a second depth block adjacent to right side of the current depth block, and the extended left neighboring column includes at least one extended left-column reconstructed depth sample located adjacent to left side of a third depth block adjacent to bottom side of the current depth block; and

encoding or decoding each segment of the current depth block using the prediction value,

wherein the current depth block corresponds to an N×N block, N is an integer, upper-left corner sample of the current block is designated as P 0 , 0 , lower-right corner sample of the current block is designated as P (N−1) , (N−1) , the extended top neighboring row comprises {P N , −1 , . . . , P 2N−1 , −1 }, the extended left neighboring column comprises {P −1,N , . . . ,P −1,2N−1 },

wherein when a result of a first test associated with two top row reference depth samples of the current depth block is identical to a result of a second test associated with two left column reference depth samples of the current depth block:

selecting P X , −1 or P −1,X as a prediction value for one segment of the current depth block according to a comparison of an absolute difference of two ending samples of the extended top neighboring row and an absolute difference of two ending samples of the extended left neighboring column, wherein X is selected from a group of integers starting from 0 to (2N−1).

2. The method of claim 1 , wherein the current depth block is partitioned into two segments and the two segments are coded using chain coding.

3. The method of claim 1 , wherein when the absolute difference of two ending samples of the extended top neighboring row is greater than the absolute difference of two ending samples of the extended left neighboring column, selecting P X,−1 as the prediction value for said one segment of the current depth block.

4. The method of claim 1 , wherein when the absolute difference of two ending samples of the extended top neighboring row is not greater than the absolute difference of two ending samples of the extended left neighboring column, selecting P −1,X as the prediction value for said one segment of the current depth block.

5. The method of claim 1 , wherein X is 2N−1.

6. An apparatus of Intra coding for a depth block in a three-dimensional video coding system, the apparatus comprising one or more electronics configured to:

receive input data associated with a current depth block, wherein the current depth block is partitioned into one or more segments;

receive reconstructed neighboring depth samples of the current depth block;

derive a prediction value for each segment based on reconstructed neighboring depth samples, wherein the reconstructed neighboring depth samples for at least one segment comprise at least one reconstructed sample from an extended top neighboring row or an extended left neighboring column, the extended top neighboring row includes at least one extended top-row reconstructed depth sample located adjacent to top side of a second depth block adjacent to right side of the current depth block, and the extended left neighboring column includes at least one extended left-column reconstructed depth sample located adjacent to left side of a third depth block adjacent to bottom side of the current depth block; and

encode or decode each segment of the current depth block using the prediction value,

wherein the current depth block corresponds to an N×N block, N is an integer, upper-left corner sample of the current block is designated as P 0 , 0 , lower-right corner sample of the current block is designated as P (N−1) , (N−1) , the extended top neighboring row comprises {P N , −1 , . . . ,P 2N−1 }, the extended left neighboring column comprises {P −1,N , . . . ,P −1,2N−1 },

wherein when a result of a first test associated with two top row reference depth samples of the current depth block is identical to a result of a second test associated with two left column reference depth samples of the current depth block:

P X , −1 or P −1,X is selected as a prediction value for one segment of the current depth block according to a comparison of an absolute difference of two ending samples of the extended top neighboring row and an absolute difference of two ending samples of the extended left neighboring column, wherein X is selected from a group of integers starting from 0 to (2N−1).

7. The apparatus of claim 6 , wherein when the absolute difference of two ending samples of the extended top neighboring row is greater than the absolute difference of two ending samples of the extended left neighboring column, P X,−1 is selected as the prediction value for said one segment of the current depth block.

8. The apparatus of claim 6 , wherein when the absolute difference of two ending samples of the extended top neighboring row is not greater than the absolute difference of two ending samples of the extended left neighboring column, P −1,X is selected as the prediction value for said one segment of the current depth block.

9. The apparatus of claim 6 , wherein X is 2N−1.