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AssigneeSony Corporation
InventorsKazushi Sato, Osamu Sunohara, Teruhiko Suzuki, Peter Kuhn, Yoichi Yagasaki, Kuniaki Takahashi
Estimating the term…
An image decoding apparatus for decoding a bit stream includes a receiving unit that receives the bit stream and a weight parameter that is added to a luma quantization parameter. The image decoding apparatus also includes a decoding unit that decodes the bit stream and generates a chroma component of quantized coefficients. Further, the image decoding apparatus includes a dequantization unit that performs dequantization on the chroma component of quantized coefficients using a chroma quantization parameter calculated on the basis of a luma quantization parameter weighted by the weight parameter. In addition, the image decoding apparatus includes a transform unit that performs an inverse orthogonal transform.
An image decoding method for decoding a bit stream in an image decoding apparatus, the method comprising:
An image decoding apparatus for decoding a bit stream, the apparatus comprising:
An image decoding apparatus for decoding a bit stream, the apparatus comprising:
Dependencies are inferred from the claim text.
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Characterised by the element, parameter or selection affected or controlled by the adaptive coding: quantisation
Quantisation: details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
The unit being an image region, e.g. an object: the region being a block, e.g. a macroblock
Characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the…: the…
Term ended 27 Nov 2022 (estimated)
1. Field of the Invention
The present invention relates to a method and apparatus for coding image information, a method and apparatus for decoding image information, a method and apparatus for coding and decoding image information, and a system for coding and transmitting image information, for use in receiving, via a network medium such as satellite broadcasting, cable television, or the Internet, image information (bit stream) compressed by means of an orthogonal transform such as a discrete cosine transform or a Karhunen-Loeve transform and motion compensation according to the MPEG (Moving Picture Experts Group) standard or the standard H.26x, or for use in processing image information on a storage medium such as an optical disk, a magnetic disk, or a flash memory.
2. Description of the Related Art
FIG. 1 is a block diagram showing an example of a construction of an image information coding apparatus according to an embodiment of the present invention;
FIG. 2 is a block diagram showing an example of a construction of an image information decoding apparatus according to an embodiment of the present invention;
FIG. 3 is a diagram showing a default weighting matrix applied to intra macroblocks or luminance signals, stored in a weighter of the image information coding apparatus shown in FIG. 1;
The present invention is described in further detail below with reference to specific embodiments in conjunction with the accompanying drawings.
As a first embodiment of the present invention, an image signal coder for producing compressed image information by dividing an input image signal into blocks, performing an orthogonal transform on the blocks on a block-by-block basis, and quantizing resultant orthogonal transform coefficients, and an image signal decoder for decoding coded image information by dequantizing it and performing an inverse transform are described.
In the image information coding apparatus and the image information decoding apparatus according to the present embodiment, as will be described in detail later, weighting is performed on a parameter specifying one of elements of a sequence of numbers arranged in accordance with a predetermined rule in correspondence to quantization step sizes thereby making it possible to use greater quantization step sizes in quantizing orthogonal transform coefficients in a high frequency range in which the great quantization step sizes does not result in significant visually-perceptible degradation, than in a low frequency range in which degradation is easily perceptible, and also making it possible to prevent a spurious contour line from being created in an image including a part with gradually varying pixel values