CN-116567236-B - Image decoding method

Abstract

The invention provides an image decoding method. The complexity of encoding/decoding of moving images is reduced. The image decoding device (31) is provided with a CN information decoding unit (10) which divides the encoded nodes in a hierarchical manner by at least one of binary tree division and trigeminal tree division, and the CN information decoding unit restricts the division method of the target node by referring to the division method of a node immediately above the target node.

Inventors

• YASUGI YUKINOBU
• AONO TOMOKO
• IKAI TOMOHIRO

Assignees

• 夏普株式会社
• 鸿颖创新有限公司

Dates

Publication Date

20260512

Application Date

20171213

Priority Date

20161216

Claims (1)

1. 1. An image decoding method for decoding a picture for each coding tree unit, characterized in that, Performing BT split possibility determination based on a width of an object block, a height of the object block, a minimum size of a coding unit, a maximum size of the coding unit, and a hierarchy of the object block; When 1) the width or height of the object block is 2 times or more the minimum size of the encoding means, 2) the width and height of the object block is not more than the maximum size of the encoding means, and 3) the hierarchy of the object block is smaller than the maximum hierarchy value, it is determined that binary tree segmentation, BT segmentation, is possible; performing TT segmentation possible determination based on the width of the object block, the height of the object block, the minimum size of the coding unit, the maximum size of the coding unit, and the hierarchy of the object block; Determining that it is possible to perform a three-tree division, TT division, when 1) the width or height of the object block is 4 times or more the minimum size of the encoding means, 2) the width and height of the object block is equal to or less than the maximum size of the encoding means, and 3) the hierarchy of the object block is less than the maximum hierarchy value; determining whether a PT split flag indicating whether BT split or TT split is to be performed on the object block is required to be decoded, and decoding the PT split flag if so; When the PT division flag indicates BT division or TT division of the target block, determining whether or not decoding of a division direction flag indicating a division direction of the target block is necessary, and when decoding is necessary, decoding the division direction flag; Determining whether a split mode selection flag indicating BT split or TT split is required to be decoded, decoding the split mode selection flag if it is required to be decoded, and Performing BT segmentation or TT segmentation on the object block based on the segmentation direction mark and the segmentation mode selection mark, In the method of decoding an image in accordance with the present invention, If the target block is a central block among three blocks obtained by TT-dividing a directly upper block and TT-dividing the directly upper block in the horizontal direction, the target block is prohibited from being BT-divided in the horizontal direction.

Description

Image decoding method The present invention is a divisional application of an invention patent application having a filing date of 2017, 12, 13 and a filing number of 201780077762.3, and having an invention name of "image decoding apparatus and image encoding apparatus". Technical Field Embodiments of the present invention relate to a predicted image generating apparatus, a moving image decoding apparatus, and a moving image encoding apparatus. Background In order to efficiently transmit or record a moving image, a moving image encoding device that generates encoded data by encoding a moving image, and a moving image decoding device that generates a decoded image by decoding the encoded data are utilized. Specific moving image coding methods include, for example, those proposed in h.264/AVC and HEVC (High-EFFICIENCY VIDEO CODING, high efficiency video coding). In such a moving image encoding system, an image (picture) constituting a moving image is managed by a hierarchical structure composed of a slice obtained by dividing the image, a Coding Unit (also referred to as Coding Unit: CU) obtained by dividing the slice, and a Prediction Unit (PU) and a Transform Unit (TU) which are blocks obtained by dividing the Coding Unit, and is encoded/decoded for each CU. In such a moving image encoding system, a prediction image is generally generated based on a locally decoded image obtained by encoding/decoding an input image, and a prediction residual (also referred to as a "differential image" or a "residual image") obtained by subtracting the prediction image from the input image (original image) is encoded. As a method for generating a predicted image, inter-picture prediction (inter-frame prediction) and intra-picture prediction (intra-frame prediction) are exemplified. Further, as a technique of encoding and decoding a moving image in recent years, non-patent documents 1 and 2 are cited. Prior art literature Non-patent literature Non-patent literature 1：″Algorithm Description of Joint Exploration Test Model 4″,JVET-D1001,Joint Video Exploration Team(JVET)of ITU-T SG 16 WP 3 and ISO/IEC JTC 1/SC 29/WG 11,15-21October 2016 Non-patent literature 2：″Multi-Type-Tree″,JVET-D0117,Joint Video Exploration Team(JVET)of ITU-T SG 16WP 3and ISO/IEC JTC 1/SC 29/WG 11,15-21October 2016 Disclosure of Invention Problems to be solved by the invention As a partition format of the encoding Node (CN: encoding Node), in non-patent document 2, BT (Binary Tree) partition and TT (TRIPLE TREE, trigeminal Tree) partition are introduced in addition to QT (Quad Tree) partition, and the partition pattern of the CU increases, and encoding/decoding becomes complicated. In addition, it is still not easy to realize a complicated division pattern, and further improvement is demanded in terms of improvement of coding efficiency. The present invention has been made in view of the above-described problems, and an object thereof is to provide an image decoding device and an image encoding device capable of reducing the complexity of encoding/decoding a moving image. Further, an image decoding device and an image encoding device are provided that can realize a more complex division pattern with less division depth. Means for solving the problems In order to solve the above-described problems, an image decoding apparatus according to an aspect of the present invention is an image decoding apparatus for decoding a picture for each code tree unit, the image decoding apparatus including a partition unit for hierarchically partitioning a code node of the code tree unit by at least one of binary tree partitioning and trigeminal tree partitioning, wherein the partition unit restricts a partition mode of a target node with reference to a partition mode of a node immediately above the target node. In the image decoding device according to an aspect of the present invention, the image decoding device decodes a picture for each code tree unit includes a dividing unit that divides the code nodes of the code tree unit in a hierarchical manner, and when the target node is rectangular with an aspect ratio equal to or greater than a predetermined value, the dividing unit restricts the dividing of the target node by three-tree division that generates a boundary along a longitudinal direction of the target node. An image decoding device according to an aspect of the present invention is an image decoding device for decoding a picture for each code tree unit, the image decoding device including a partition unit for hierarchically partitioning a code node of the code tree unit by at least one of binary tree partitioning and trigeminal tree partitioning, the partition unit limiting partitioning of a target node by referring to a depth variable common to the binary tree partitioning and the trigeminal tree partitioning. An image coding apparatus according to an aspect of the present invention is an image coding apparatus for coding a picture by dividing the picture into co