Method and an apparatus for encoding/decoding an image

A video decoder comprising:

• an entropy-decoding module that obtains video information from a received bitstream;
• a prediction module that constructs a predicted block corresponding to a prediction target block by predicting pixel values in the prediction target block on the basis of a plurality of neighboring pixels adjacent to the prediction target block;
• and
• a reconstructed block constructing module that constructs a reconstructed block on the basis of the predicted block,
• wherein the prediction module
• determines a target boundary by determining a plurality of boundary pixels indicating the target boundary in the prediction target block on the basis of the decoded video information, and
• performs a prediction on a plurality of prediction target regions, into which the prediction target block is split by the target boundary, on the basis of different neighboring pixels out of the plurality of neighboring pixels,
• wherein the plurality of boundary pixels include N boundary pixels {p0, p1, . . . , pn, . . . , pN-1}, N is a positive integer, and n is an integer of 0 to N−1,
• wherein the video information includes information indicating a chain code corresponding to the boundary pixel pn,
• wherein the chain code indicates an angle between a first progress direction from the boundary pixel pn−1 to the boundary pixel pn and a second progress direction from the boundary pixel pn to the boundary pixel pn+1,
• wherein the chain code is selected from a chain code group comprising 7 chain codes including a first chain code representing 0 degree, a second chain code representing 45 degree, a third chain code representing −45 degree, a fourth chain code representing 90 degree, a fifth chain code representing −90 degree, a sixth chain code representing 135 degree and a seventh chain code representing −135 degree, and
• wherein the first chain code is represented by a binary code “0”, the second chain code is represented by a binary code “10”, the third chain code is represented by a binary code “110”, the fourth chain code is represented by a binary code “1110”, the fifth chain code is represented by a binary code “11110”, the sixth chain code is represented by a binary code “111110” and the seventh chain code is represented by a binary code “111111”.

A video decoding method comprising the steps of:

• receiving and decoding encoded video information;
• determining a target boundary by determining a plurality of boundary pixels indicating the target boundary in the prediction target block on the basis of the decoded video information;
• determining a plurality of prediction target regions into which the prediction target block is split by the target boundary;
• constructing a predicted block corresponding to the prediction target block by performing a prediction on the plurality of prediction target regions on the basis of different neighboring pixels out of the plurality of neighboring pixels adjacent to the prediction target block;
• and
• constructing a reconstructed block on the basis of the predicted block,
• wherein the plurality of boundary pixels include N boundary pixels {p0, p1, . . . , pn, . . . , pN-1}, N is a positive integer, and n is an integer of 0 to N−1,
• wherein the video information includes information indicating a chain code corresponding to the boundary pixel pn,
• wherein the chain code indicates an angle between a first progress direction from the boundary pixel pn−1 to the boundary pixel pn and a second progress direction from the boundary pixel pn to the boundary pixel pn+1,
• wherein the chain code is selected from a chain code group comprising 7 chain codes including a first chain code representing 0 degree, a second chain code representing 45 degree, a third chain code representing −45 degree, a fourth chain code representing 90 degree, a fifth chain code representing −90 degree, a sixth chain code representing 135 degree and a seventh chain code representing −135 degree, and
• wherein the first chain code is represented by a binary code “0”, the second chain code is represented by a binary code “10”, the third chain code is represented by a binary code “110”, the fourth chain code is represented by a binary code “1110”, the fifth chain code is represented by a binary code “11110”, the sixth chain code is represented by a binary code “111110” and the seventh chain code is represented by a binary code “111111”.