CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Patent Application of PCT International Patent Application No. PCT/KR2017/011055 (filed on Sep. 29, 2017) under 35 U.S.C. § 371, which claims priority to Korean Patent Application Nos. 10-2016-0127862 (filed on Oct. 4, 2016) and 10-2016-0127863 (filed on Oct. 4, 2016), the teachings of which are incorporated herein in their entireties by reference.

TECHNICAL FIELD

The present invention relates to a method and an apparatus for processing video signal.

BACKGROUND ART

Recently, demands for high-resolution and high-quality images such as high definition (HD) images and ultra-high definition (UHD) images have increased in various application fields. However, higher resolution and quality image data has increasing amounts of data in comparison with conventional image data. Therefore, when transmitting image data by using a medium such as conventional wired and wireless broadband networks, or when storing image data by using a conventional storage medium, costs of transmitting and storing increase. In order to solve these problems occurring with an increase in resolution and quality of image data, high-efficiency image encoding/decoding techniques may be utilized.

Image compression technology includes various techniques, including: an inter-prediction technique of predicting a pixel value included in a current picture from a previous or subsequent picture of the current picture; an intra-prediction technique of predicting a pixel value included in a current picture by using pixel information in the current picture; an entropy encoding technique of assigning a short code to a value with a high appearance frequency and assigning a long code to a value with a low appearance frequency; etc. Image data may be effectively compressed by using such image compression technology, and may be transmitted or stored.

In the meantime, with demands for high-resolution images, demands for stereographic image content, which is a new image service, have also increased. A video compression technique for effectively providing stereographic image content with high resolution and ultra-high resolution is being discussed.

DISCLOSURE

Technical Problem

An object of the present invention is to provide a method and an apparatus for efficiently performing intra-prediction for an encoding/decoding target block in encoding/decoding a video signal.

An object of the present invention is to provide a method and an apparatus for performing intra prediction through a weighted prediction using a plurality of reference samples in encoding/decoding a video signal.

An object of the present invention is to provide a method and an apparatus for refining a prediction sample generated through intra prediction using an offset in encoding/decoding a video signal.

An object of the present invention is to provide a method and an apparatus for refining a prediction sample generated through intra prediction using an offset, and further using a different offset in a predetermined unit in encoding/decoding a video signal.

The technical objects to be achieved by the present invention are not limited to the above-mentioned technical problems. And, other technical problems that are not mentioned will be apparently understood to those skilled in the art from the following description.

Technical Solution

A method and an apparatus for decoding a video signal according to the present invention may determine an intra prediction mode of a current block, derive reference samples from neighboring samples of the current block, obtain a first prediction sample for the current block, based on the intra prediction mode and the reference samples, determine an offset for the first prediction sample, and obtain a second prediction sample by applying the offset to the first prediction sample.

A method and an apparatus for encoding a video signal according to the present invention may determine an intra prediction mode of a current block, derive reference samples from neighboring samples of the current block, obtain a first prediction sample for the current block, based on the intra prediction mode and the reference samples, determine an offset for the first prediction sample, and obtain a second prediction sample by applying the offset to the first prediction sample.

In a method and an apparatus for encoding/decoding a video signal according to the present invention, whether to apply the offset to the first prediction sample may be determined based on the intra prediction mode of the current block.

In a method and an apparatus for encoding/decoding a video signal according to the present invention, the offset may be determined based on a weighted sum of the reference samples.

In a method and an apparatus for encoding/decoding a video signal according to the present invention, a weight applied to each of the reference samples is determined based on a distance from the first prediction sample.

In a method and an apparatus for encoding/decoding a video signal according to the present invention, the reference samples include a reference sample at a fixed position and a reference sample determined dependently on a position of the first prediction samples.

In a method and an apparatus for encoding/decoding a video signal according to the present invention, the reference sample at the fixed position may include a reference sample adjacent to a top left corner of the current block, and the reference sample determined dependently on the position of the first prediction sample may include at least one of a reference sample on a same horizontal line as the first prediction sample or a reference sample on a same vertical line as the first prediction sample.

In a method and an apparatus for encoding/decoding a video signal according to the present invention, each of the reference samples may be included in a different reference line.

The features briefly summarized above for the present invention are only illustrative aspects of the detailed description of the invention that follows, but do not limit the scope of the invention.

Advantageous Effects

According to the present invention, intra-prediction may be performed efficiently for an encoding/decoding target block.

According to the present invention, intra prediction can be performed based on a weighted prediction using a plurality of reference samples.

According to the present invention, encoding/decoding efficiency may be improved by refining a prediction sample generated through intra prediction.

The effects obtainable by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the description below.

