Image coding apparatus, image coding method, image decoding apparatus, image decoding method, and storage medium

Abstract

An image coding apparatus includes a block dividing unit configured to divide an input image into a plurality of blocks, a prediction unit configured to perform prediction based on coded pixels to generate prediction errors, a transformation unit configured to perform orthogonal transform to the prediction errors to generate transform coefficients, a quantization matrix generation unit configured to generate quantization matrices that are used to quantize the transform coefficients, a quantization matrix coding unit configured to calculate difference values by scanning the quantization matrices and to code the difference values, a quantization unit configured to generate quantization coefficients by quantizing the generated transform coefficients using the quantization matrices, and a coefficient coding unit configured to code the quantization coefficients, wherein the quantization matrix coding unit is configured to scan coefficients of the quantization matrices in a unidirectional manner to calculate the difference value.

Description

technical field [0001] The present invention relates to an image encoding device, an image encoding method, an image decoding device, an image decoding method and a storage medium. More specifically, the present invention relates to an encoding / decoding method of a quantization matrix in an image. Background technique [0002] H.264 / MPEG-4 AVC (hereinafter referred to as H.264) is known as a compression recording standard for moving images. With (ITU-T H.264 (03 / 2010) Advanced Video Coding for General Audiovisual Services) H.264, each element of the quantization matrix can be changed to an arbitrary value by encoding scaling list information. According to chapter 7.3.2.1.1.1 of H.264, each element of a quantization matrix can take an arbitrary value by adding a delta scale which is the difference between an element and its previous element. [0003] For H.264, each element of the quantization matrix is ​​scanned in a direction from the element corresponding to the low freq...

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Problems solved by technology

[0004] However, with zigzag scanning used in H.264, since each element of the quantization matrix is ​​scanned in a diagonal direction, the code amount of the quantization matrix increases according to the characteristics of the quantization matrix

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