TECHNICAL FIELD

The present disclosure relates to a method and a device for processing a video signal.

BACKGROUND ART

Recently, demands for high-resolution and high-quality images such as HD (High Definition) images and UHD (Ultra High Definition) images have increased in a variety of application fields. As image data becomes high-resolution and high-quality, the volume of data relatively increases compared to the existing image data, so when image data is transmitted by using media such as the existing wire and wireless broadband circuit or is stored by using the existing storage medium, expenses for transmission and expenses for storage increase. High efficiency image compression technologies may be utilized to resolve these problems which are generated as image data becomes high-resolution and high-quality.

There are various technologies such as an inter prediction technology which predicts a pixel value included in a current picture from a previous or subsequent picture of a current picture with an image impression technology, an intra prediction technology which predicts a pixel value included in a current picture by using pixel information in a current picture, an entropy encoding technology which assigns a short sign to a value with high appearance frequency and assigns a long sign to a value with low appearance frequency and so on, and image data may be effectively compressed and transmitted or stored by using these image compression technologies.

On the other hand, as demands for a high-resolution image have increased, demands for stereo-scopic image contents have increased as a new image service. A video compression technology for effectively providing high-resolution and ultra high-resolution stereo-scopic image contents has been discussed.

DISCLOSURE
Technical Problem

The present disclosure intends to provide a block partition method and device in a tree structure.

The present disclosure intends to provide a method and a device for deriving an intra prediction mode for intra prediction.

The present disclosure intends to provide a method and a device for deriving an extended reference pixel for intra prediction.

The present disclosure intends to provide a method and a device for performing improved intra prediction.

Technical effects of the present disclosure may be non-limited by the above-mentioned technical effects, and other unmentioned technical effects may be clearly understood from the following description by those having ordinary skill in the technical field to which the present disclosure pertains.

Technical Solution

An image decoding method according to the present disclosure may determine a current block through tree structure-based block partition, configure one or more sub-blocks from the current block by subsampling the current block and decode a sub-block belonging to the current block in predetermined scan order.

In an image decoding method according to the present disclosure, the tree structure-based block partition may include at least one of penta-tree partition or quad-tree partition.

In an image decoding method according to the present disclosure, the quad-tree partition partitions a coding block into 4 coding blocks in one direction of a vertical direction or a horizontal direction and the quad-tree partition may be performed by selectively using one of a plurality of partition types having a predetermined partition ratio.

In an image decoding method according to the present disclosure, the current block may be divided in a unit of a N×M-sized sub-region and the sub-block may be configured with pixels at the same position extracted from a unit of each sub-region.

In an image decoding method according to the present disclosure, the subsampling may be performed only for one direction of a horizontal direction or a vertical direction.

In an image decoding method according to the present disclosure, a size of the sub-region unit may be adaptively determined based on an encoding parameter for the current block and the encoding parameter may include at least one of a slice type, a block size, an intra prediction mode, directivity of an intra prediction mode, a component type, a transform type, whether transform is skipped or scan order.

In an image decoding method according to the present disclosure, decoding the sub-block may include at least one of deriving a reference pixel for prediction of the sub-block, deriving an intra prediction mode for prediction of the sub-block or performing intra prediction of the sub-block.

In an image decoding method according to the present disclosure, the reference pixel may include at least one of a pixel adjacent to the current block or a pixel of a pre-reconstructed sub-block in the current block.

In an image decoding method according to the present disclosure, the intra prediction mode may be derived from a MPM list of the current block, the MPM list may include a plurality of MPM candidates and at least one of the plurality of MPM candidates may be derived by using at least one of a left-middle block, a top-center block, a right block or a bottom block of the current block.

In an image decoding method according to the present disclosure, intra prediction of the sub-block may be performed by using at least one of an intra prediction method based on an intra prediction mode or an intra prediction method based on a linear model.

An image encoding method according to the present disclosure may include determining a current block through tree structure-based block partition, configuring one or more sub-blocks from the current block by subsampling the current block and encoding a sub-block belonging to the current block in predetermined scan order.

In an image encoding method according to the present disclosure, the tree structure-based block partition may include at least one of penta-tree partition or quad-tree partition.

In an image encoding method according to the present disclosure, the quad-tree partition partitions a coding block into 4 coding blocks in one direction of a vertical direction or a horizontal direction and the quad-tree partition may be performed by selectively using one of a plurality of partition types having a predetermined partition ratio.

In an image encoding method according to the present disclosure, the current block may be divided in a unit of a N×M-sized sub-region and the sub-block may be configured with pixels at the same position extracted from a unit of each sub-region.

In an image encoding method according to the present disclosure, the subsampling may be performed only for one direction of a horizontal direction or a vertical direction.

In an image encoding method according to the present disclosure, a size of the sub-region unit may be adaptively determined based on an encoding parameter for the current block and the encoding parameter may include at least one of a slice type, a block size, an intra prediction mode, directivity of an intra prediction mode, a component type, a transform type, whether transform is skipped or scan order.

In an image encoding method according to the present disclosure, encoding the sub-block may include at least one of deriving a reference pixel for prediction of the sub-block, determining an intra prediction mode for prediction of the sub-block or performing intra prediction of the sub-block.

In an image encoding method according to the present disclosure, the reference pixel may include at least one of a pixel adjacent to the current block or a pixel of a pre-reconstructed sub-block in the current block.

In an image encoding method according to the present disclosure, the intra prediction mode may be determined from a MPM list of the current block, the MPM list may include a plurality of MPM candidates and at least one of the plurality of MPM candidates may be derived by using at least one of a left-middle block, a top-center block, a right block or a bottom block of the current block.

In an image encoding method according to the present disclosure, intra prediction of the sub-block may be performed by using at least one of an intra prediction method based on an intra prediction mode or an intra prediction method based on a linear model.

A computer readable recording medium according to the present disclosure may store a bitstream generated by an image encoding method described above or decoded by an image decoding method.

A computing device according to the present disclosure may store a program (instructions) for transmitting a bitstream generated by an image encoding method described above.

Features briefly summarized above with respect to the present disclosure are just an exemplary aspect of a detailed description of the present disclosure described below, and they do not limit a scope of the present disclosure.

Technical Effect

According to the present disclosure, a size and a shape of a coding block, a prediction block or a transform block may be effectively determined through block partition in various tree structures.

According to the present disclosure, encoding efficiency of intra prediction may be improved by using an extended MPM candidate and a reference pixel as a basis.

According to the present disclosure, encoding efficiency may be improved through improved intra prediction.

Effects obtainable from the present disclosure are not limited to the above-mentioned effects and other unmentioned effects may be clearly understood from the following description by those having ordinary skill in the technical field to which the present disclosure pertains.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram showing an image encoding device according to an embodiment of the present disclosure.

FIG. 2 is a block diagram showing an image decoding device according to an embodiment of the present disclosure.

FIGS. 3 to 12 show a block partition method according to the present disclosure.

FIGS. 13 to 17 show encoding order according to a block partition method according to the present disclosure.

FIG. 18 shows a sub-block-based intra prediction method according to the present disclosure.

As an embodiment to which the present disclosure is applied, FIG. 19 shows a method of configuring a plurality of sub-blocks by subsampling a current block.

As an embodiment to which the present disclosure is applied, FIGS. 20 to 25 show a method of deriving a reference pixel for prediction of a sub-block.

As an embodiment to which the present disclosure is applied, FIGS. 26 and 27 show predefined intra prediction modes available for a current block.

As an embodiment to which the present disclosure is applied, FIGS. 28 and 29 show a surrounding reference position used when configuring a MPM list.

As an embodiment to which the present disclosure is applied, FIGS. 30 to 34 show a method of generating a prediction pixel per intra prediction mode.

As an embodiment to which the present disclosure is applied, FIG. 35 shows an intra prediction method based on a linear model.

BEST MODE