WO2011052216A1

WO2011052216A1 - Image encoding method, image decoding method, image encoding device and image decoding device

Info

Publication number: WO2011052216A1
Application number: PCT/JP2010/006384
Authority: WO
Inventors: チョンスーンリム; 陽司柴原; 西　孝啓
Original assignee: パナソニック株式会社
Priority date: 2009-10-30
Filing date: 2010-10-29
Publication date: 2011-05-05
Also published as: TW201143448A

Abstract

Provided is an image encoding method which achieves an improvement in encoding efficiency while suppressing a deterioration in image quality. The image encoding method is an image encoding method for encoding an image in each block, and comprises a conversion step for converting a plurality of pixel values contained in a block into a plurality of frequency coefficients (S2601), and a quantization step for quantizing the plurality of frequency coefficients using a parameter set including a quantization scaling matrix determined for each block and/or a quantization offset matrix determined for each block (S2602).

Description

Image encoding method, image decoding method, image encoding device, and image decoding device

The present invention relates to an image encoding method for encoding an image for each block and an image decoding method for decoding an image for each block.

In any image or video coding scheme, quantization is an important step in compressing data by removing some information in the image or video. Quantization is typically performed in the transform domain so that the image or data can be more appropriately compressed by losing information in the quantization process.

In most image or video coding schemes, the quantization process can be controlled by quantization parameters. The quantization parameter is a value indicating the degree of quantization. At this time, if the value of the quantization parameter is large, the amount of compression increases, and more information is lost. And vice versa. The quantization parameter is typically determined by the amount of data generated by encoding.

In addition to quantization parameters, some image or video coding schemes also quantize and inverse by quantized scaling values (also simply called scaling values) and quantization offset values (also simply called offset values). Some can control the quantization process. Similarly to the quantization parameter, the quantization scaling value is also a value indicating the degree of quantization. By multiplying the quantization scaling value by the quantization parameter, a new degree of quantization is obtained. The quantization offset value is a value for adjusting the quantization value or the inverse quantization value.

An example of the inverse quantization process can be expressed by the following equation. Hereinafter, the positive quantization offset value is described as meaning subtraction of the inverse quantization value, but even if the positive quantization offset value is replaced when the inverse quantization value is added, The essence of processing does not change.

AbsCoeff = ((abs (QuantizedCoeff) << 7) -OffsetValue) * LevelScale * ScaleValue >> QShift

Here, LevelScale and QShift are controlled by quantization parameters, ScaleValue is a quantization scaling value, and OffsetValue is a quantization offset value used for inverse quantization processing. Here, the positive quantization offset value means that a positive value is subtracted from the value obtained as a result of the inverse quantization process.

If the frequency components of the transform block are different, different quantization scaling values and quantization offset values can be set. These values thus constitute a quantized scaling matrix (also referred to simply as scaling matrix) and a quantized offset matrix (also referred to simply as offset matrix). One value of the quantization scaling matrix and one value of the quantization offset matrix are used in particular for the quantization and inverse quantization of one frequency component of the transformed image data block.

That is, the quantization scaling matrix is composed of scaling values for each frequency. Further, the quantization offset matrix is composed of offset values for each frequency. Note that the quantization offset matrix and the quantization scaling matrix may be simply referred to as a quantization matrix or a matrix.

There are several prior art available that illustrate using the quantized scaling matrix to improve the subjective image quality of the reconstructed image. There are several prior arts that improve the encoding performance of video without using the quantization offset value in the quantization process but in the inverse quantization process. For example, Patent Document 1 describes an image encoding device that encodes an image using a quantization offset value.

JP 2007-081474 A

However, there are only a few prior art describing the use of quantized offset values for inverse quantization and can be used to explain the use of quantized offset matrices for inverse quantization to improve subjective image quality. There is no prior art. There is also no prior art that describes using a quantized offset value and using a quantized scaling matrix to improve image quality.

In video coding schemes such as ISO / IEC 14496-10 (MPEG-4 AVC), the quantization scaling matrix can be encoded into either a sequence header or a picture header, and these quantization scaling matrices are Used for inverse quantization processing. However, there is no available prior art that adaptively adjusts the quantization scaling matrix or quantization offset value in the picture according to the quantization parameter of the block.

One of the problems of the prior art is that the use of separate quantization offset values for the quantization process and the inverse quantization process in order to improve the accuracy of the minimum inverse quantization value increases the compression bits of the image. . In order to reduce the increase in additional bits, a larger quantization scaling value is usually required for further compression.

However, if the same quantization scaling value is used for all frequency components of the block, a new artifact is usually generated in the reconstructed image. Additional artifacts such as ringing noise occur in certain areas of the reconstructed image due to the use of larger quantization scaling values to offset the bit increase caused by the use of positive quantization offset values To do.

Another challenge of the prior art is the flexibility to adjust the quantization scaling matrix and quantization offset matrix used for the inverse quantization process of a picture without transmitting additional information about the adjusted matrix Is lacking.

Therefore, an object of the present invention is to provide an image encoding method that improves the encoding efficiency while suppressing deterioration of image quality.

In order to solve the above problems, an image coding apparatus according to the present invention is an image coding method for coding an image for each block, and converts a plurality of pixel values included in a block into a plurality of frequency coefficients. The plurality of frequency coefficients are quantized using a parameter set including at least one of a step, a quantization scaling matrix determined for each block, and a quantization offset matrix determined for each block A quantization step.

Thereby, a quantization scaling matrix or a quantization offset matrix determined for each block is used. Therefore, deterioration in image quality is suppressed and coding efficiency is improved.

The image encoding method further includes a writing step of writing a plurality of quantization scaling matrices corresponding to a plurality of block sizes and a plurality of quantization offset values corresponding to the plurality of block sizes in a header. In the writing step, the first quantization offset value corresponding to the first block size among the plurality of block sizes is written as one of the plurality of quantization offset values, and in the writing step, The first quantization scaling matrix corresponding to the first block size is written as one of the plurality of quantization scaling matrices, and the writing step is smaller than the first block size among the plurality of block sizes. A second quantization offset value corresponding to the second block size. The second quantization offset value larger than the first quantization offset value is written as one of the plurality of quantization offset values, and in the writing step, the second block size corresponding to the second block size is written. Write a second quantization scaling matrix that is a quantization scaling matrix smaller than the first quantization scaling matrix as one of the plurality of quantization scaling matrices, and in the converting step, the plurality of block sizes Converting the plurality of pixel values included in the block formed with any block size into the plurality of frequency coefficients, and in the quantization step, of the plurality of quantization scaling matrices, the block of the block The quantization scaling factor corresponding to the block size Rikusu, and said plurality of quantization offset value, using the parameter set including quantization offset value corresponding to the block size of the block, a plurality of frequency coefficients may be quantized.

This applies a quantization scaling matrix and a quantization offset value suitable for the block size.

The image encoding method may further include calculating the distortion cost indicating the magnitude of distortion caused by the quantization of the plurality of frequency coefficients, or the edge included in the image. A size determining step of determining the block size of the block in dependence on the edge detected by detecting, wherein the converting step includes the block included in the block formed with the determined block size A plurality of pixel values may be converted into the plurality of frequency coefficients.

Thus, an appropriate block size is selected according to the characteristics of the image.

Further, the image encoding method is further determined by a quantization parameter determining step for determining a quantization parameter corresponding to the block, and a matrix determining step for determining the quantization scaling matrix corresponding to the block Modifying the quantization scaling matrix depending on the determined quantization parameter, thereby correcting a slope indicating a ratio of a change in the quantization scaling value to a change in the frequency in the determined quantization scaling matrix. A matrix modification step, wherein the quantization step includes quantizing the plurality of frequency coefficients using the modified quantization scaling matrix and the parameter set including the determined quantization parameter. Good.

This allows the quantization scaling matrix to be flexibly modified according to the quantization parameter.

In the matrix correction step, when the determined quantization parameter is a second quantization parameter larger than the first quantization parameter, and when the determined quantization parameter is the first quantization parameter The quantization scaling matrix may be modified so that the slope becomes steeper than.

Thus, when the quantization parameter is large, the difference between a plurality of quantization scaling values becomes large. Therefore, the image is more appropriately encoded.

In addition, the image encoding method is further determined: a quantization parameter determining step for determining a quantization parameter corresponding to the block; and a matrix determining step for determining the quantization offset matrix corresponding to the block By correcting the quantization offset matrix depending on the determined quantization parameter, a slope indicating a ratio of a change in the quantization offset value to a change in the frequency in the determined quantization offset matrix is corrected. A matrix modification step, wherein the quantization step includes quantizing the plurality of frequency coefficients using the modified quantization offset matrix and the parameter set including the determined quantization parameter. Good.

This allows the quantization offset matrix to be flexibly modified according to the quantization parameter.

In the matrix correction step, when the determined quantization parameter is a second quantization parameter larger than the first quantization parameter, and when the determined quantization parameter is the first quantization parameter The quantization offset matrix may be modified so that the slope becomes steeper than.

Thus, when the quantization parameter is large, the difference between a plurality of quantization offset values becomes large. Therefore, the image is more appropriately encoded.

The image encoding method may further include a first writing step of writing a first quantization offset matrix in a header, the first quantization offset matrix, and the first quantization offset matrix different from a predetermined one. A selection step of selecting the quantization offset matrix to be used for quantization of the plurality of frequency coefficients from the second quantization offset matrix, and when the second quantization offset matrix is selected, A second writing step of writing a flag indicating a value in a block header, wherein in the quantization step, the plurality of frequency coefficients are quantized using the parameter set including the selected quantization offset matrix. Also good.

This makes it possible to switch between a predetermined quantization offset matrix and a customized quantization offset matrix.

The image decoding method according to the present invention is an image decoding method for decoding an image for each block, the quantization scaling matrix determined for each block, and the quantization offset matrix determined for each block Using a parameter set including at least one of them, an inverse quantization step for inversely quantizing a plurality of frequency coefficients included in the block, and converting the plurality of inversely quantized frequency coefficients to a plurality of pixel values An inverse transformation step.

Thereby, a quantization scaling matrix or a quantization offset matrix determined for each block is used. Therefore, deterioration of image quality is suppressed. In addition, an image encoded by the same method is appropriately decoded.

The image decoding method may further include a quantization parameter determining step for determining a quantization parameter corresponding to the block, a matrix determining step for determining the quantization scaling matrix corresponding to the block, and the determined A matrix for correcting a slope indicating a ratio of a change in a quantization scaling value to a change in a frequency in the determined quantization scaling matrix by correcting the quantization scaling matrix depending on the determined quantization parameter. And the step of dequantizing the plurality of frequency coefficients using the parameter set including the modified quantization scaling matrix and the determined quantization parameter. Also good.

Thus, when the quantization parameter is large, the difference between a plurality of quantization scaling values becomes large. Therefore, the image is decoded more appropriately.

The image decoding method may further include: a quantization parameter determining step for determining a quantization parameter corresponding to the block; a matrix determining step for determining the quantization offset matrix corresponding to the block; A matrix for correcting a slope indicating a ratio of a change in the quantization offset value to a change in the frequency in the determined quantization offset matrix by correcting the quantization offset matrix depending on the determined quantization parameter. And the step of dequantizing the plurality of frequency coefficients using the parameter set including the modified quantization offset matrix and the determined quantization parameter. Also good.

Thus, when the quantization parameter is large, the difference between a plurality of quantization offset values becomes large. Therefore, the image is decoded more appropriately.

The image decoding method may further include a first analysis step of obtaining a first quantization offset matrix from the header by analyzing the header, and obtaining a flag from the block header by analyzing the block header. A second analysis step, and when the acquired flag indicates a predetermined value, a predetermined second quantization offset matrix different from the first quantization offset matrix is determined for each block If the acquired flag does not indicate the predetermined value, the first quantization offset matrix is determined as the quantization offset matrix determined for each block. A selection step of selecting, and in the inverse quantization step, Using the parameter set including the quantization offset matrix is may be inversely quantizing the plurality of frequency coefficients.

An image encoding apparatus according to the present invention is an image encoding apparatus that encodes an image for each block, the conversion unit converting a plurality of pixel values included in the block into a plurality of frequency coefficients, and the block A quantization unit that quantizes the plurality of frequency coefficients using a parameter set including at least one of a quantization scaling matrix determined for each block and a quantization offset matrix determined for each block; You may prepare.

Thereby, the image encoding method is realized as an image encoding apparatus.

An image decoding apparatus according to the present invention is an image decoding apparatus that decodes an image for each block, the quantization scaling matrix determined for each block, and the quantization offset matrix determined for each block Using a parameter set including at least one of them, an inverse quantization unit that inversely quantizes a plurality of frequency coefficients included in the block, and converts the plurality of frequency coefficients that have been inversely quantized into a plurality of pixel values. An inverse conversion unit may be provided.

Thereby, the image encoding method is realized as an image decoding apparatus.

The program according to the present invention may be a program for causing a computer to execute the steps included in the image coding method.

Thereby, the image encoding method is realized as a program.

The program according to the present invention may be a program for causing a computer to execute the steps included in the image decoding method.

Thereby, the image decoding method is realized as a program.

An integrated circuit according to the present invention is an integrated circuit that encodes an image for each block. The integrated circuit converts a plurality of pixel values included in the block into a plurality of frequency coefficients, and is determined for each block. And a quantization unit that quantizes the plurality of frequency coefficients using a parameter set including at least one of a quantization scaling matrix and a quantization offset matrix determined for each block. .

Thereby, the image encoding method is realized as an integrated circuit.

An integrated circuit according to the present invention is an integrated circuit that decodes an image for each block, and includes a quantization scaling matrix determined for each block and a quantization offset matrix determined for each block. , Using a parameter set including at least one, an inverse quantization unit that inversely quantizes a plurality of frequency coefficients included in the block, and an inverse transform that converts the plurality of frequency coefficients that have been dequantized into a plurality of pixel values May be provided.

Thereby, the image decoding method is realized as an integrated circuit.

According to the present invention, image quality deterioration is suppressed and coding efficiency is improved.

FIG. 1A is a conceptual diagram illustrating a relationship between a quantization value and an inverse quantization value. FIG. 1B is a conceptual diagram illustrating adjustment of an inverse quantization value by a quantization offset value. FIG. 2A is a conceptual diagram illustrating a relationship between an input value and a quantized value. FIG. 2B is a conceptual diagram illustrating adjustment of a quantization value by a quantization offset value. FIG. 3A is a block diagram showing an image encoding device according to Embodiment 1. FIG. 3B is a flowchart showing an image encoding process according to Embodiment 1. FIG. 4A is a configuration diagram illustrating the image decoding apparatus according to Embodiment 1. FIG. 4B is a flowchart showing image decoding processing according to Embodiment 1. FIG. 5A is a configuration diagram illustrating a more specific example of the image encoding device according to Embodiment 1. FIG. 5B is a flowchart illustrating a more specific example of the image encoding process according to Embodiment 1. FIG. 6 is a configuration diagram showing a more specific first example of the image coding apparatus according to Embodiment 1. FIG. 7 is a flowchart showing a more specific first example of the image encoding process according to the first embodiment. FIG. 8 is a configuration diagram illustrating a second more specific example of the image coding device according to Embodiment 1. FIG. 9 is a flowchart illustrating a second specific example of the image encoding process according to the first embodiment. FIG. 10 is a conceptual diagram showing the relationship between the quantization scaling matrix and the inverse quantization value. FIG. 11 is a conceptual diagram showing the relationship between the quantization offset matrix and the inverse quantization value. FIG. 12A is a configuration diagram illustrating an image encoding device according to Embodiment 2. FIG. 12B is a flowchart illustrating an image encoding process according to Embodiment 2. FIG. 13A is a block diagram showing an image decoding apparatus according to Embodiment 2. FIG. 13B is a flowchart showing image decoding processing according to Embodiment 2. FIG. 14 is a configuration diagram illustrating a more specific example of the image encoding device according to the second embodiment. FIG. 15 is a flowchart illustrating a first specific example of the image encoding process according to the second embodiment. FIG. 16 is a flowchart illustrating a second specific example of the image encoding process according to the second embodiment. FIG. 17 is a configuration diagram illustrating a more specific example of the image decoding apparatus according to the second embodiment. FIG. 18 is a flowchart showing a more specific first example of the image decoding process according to the second embodiment. FIG. 19 is a flowchart illustrating a second specific example of the image decoding process according to the second embodiment. FIG. 20A is a configuration diagram illustrating an image encoding device according to Embodiment 3. FIG. 20B is a flowchart showing an image encoding process according to Embodiment 3. FIG. 21A is a block diagram showing an image decoding apparatus according to Embodiment 3. FIG. 21B is a flowchart illustrating image decoding processing according to Embodiment 3. FIG. 22 is a diagram illustrating a bitstream according to the third embodiment. FIG. 23 is a configuration diagram illustrating a more specific example of the image coding device according to Embodiment 3. FIG. 24 is a flowchart illustrating a more specific example of the image encoding process according to the third embodiment. FIG. 25 is a configuration diagram illustrating a more specific example of the image decoding apparatus according to the third embodiment. FIG. 26 is a flowchart illustrating a more specific example of the image decoding process according to the third embodiment. FIG. 27 is a schematic diagram illustrating an example of the overall configuration of a content supply system that implements a content distribution service. FIG. 28 is a diagram illustrating an appearance of a mobile phone. FIG. 29 is a block diagram illustrating a configuration example of a mobile phone. FIG. 30 is a schematic diagram showing an example of the overall configuration of a digital broadcasting system. FIG. 31 is a block diagram illustrating a configuration example of a television. FIG. 32 is a block diagram illustrating a configuration example of an information reproducing / recording unit that reads and writes information from and on a recording medium that is an optical disk. FIG. 33 is a diagram showing an example of the structure of a recording medium that is an optical disk. FIG. 34 is a block diagram illustrating a configuration example of an integrated circuit that implements the image encoding method and the image decoding method according to each embodiment.

(Embodiment 1)
FIG. 1A is a conceptual diagram illustrating a relationship between a quantization value and an inverse quantization value. In the inverse quantization process, the larger the quantization scaling matrix, the larger the quantization scale step (also called the quantization step size or scale step).

FIG. 1B is a conceptual diagram showing adjustment of an inverse quantization value by an offset value. If the offset value is a positive value, the inverse quantization value is adjusted to a smaller value. When the offset value is a negative value, the inverse quantization value is adjusted to a larger value. The adjustment amount increases as the absolute value of the offset value increases.

FIG. 2A is a conceptual diagram showing a relationship between an input value and a quantized value. In the quantization process, the larger the quantization scaling matrix, the larger the quantization scale step.

FIG. 2B is a conceptual diagram showing adjustment of a quantization value by an offset value. If the offset value is a positive value, the quantization threshold is adjusted to a smaller value. If the offset value is negative, the quantization threshold is adjusted to a larger value. The adjustment amount increases as the absolute value of the offset value increases. As a result, the greater the offset value, the smaller the possibility that the quantized value becomes zero coefficient. Also, the smaller the offset value, the greater the possibility that the quantized value will be a zero coefficient.

Therefore, the smaller the offset value, the larger the so-called dead zone and the number of zero coefficients increases. Thereby, encoding efficiency improves. However, since a small input value is ignored, the image quality may deteriorate subjectively. On the other hand, the larger the offset value, the smaller the so-called dead zone and the number of zero coefficients decreases. Thereby, encoding efficiency falls. However, since a small input value is not ignored, the image quality may be subjectively improved.

It is preferable that the same offset value is used in quantization and inverse quantization. By using the same offset value, the quantized value and the inverse quantized value are adjusted to the same extent. For example, with a large offset value, the quantization value is adjusted to be relatively large, and the inverse quantization value is adjusted to be relatively small. Conversely, the quantized value is adjusted to be relatively small with a small offset value, and the inverse quantized value is adjusted to be relatively large. As a result, the input value and the inverse quantization value are close to each other.

However, as described above, even when the same offset value is used, the number of zero coefficients changes depending on the magnitude of the offset value, and the subjective image quality changes. That is, the larger the offset value, the lower the encoding efficiency and the image quality may be improved.

Note that different offset values may be used in quantization and inverse quantization. For example, only the inverse quantization value may be adjusted by the offset value. The input value information is reduced by quantization, but the image quality may be subjectively improved by adjusting the inverse quantization value to be large. Therefore, in inverse quantization, when a small offset value is used, the inverse quantization value becomes large, and the image quality may be subjectively improved.

Here, the magnitude of the offset value means the magnitude of the offset value in the positive direction. For example, the negative offset value is smaller than the positive offset value regardless of the magnitude of the absolute value.

FIG. 3A is a configuration diagram illustrating the image encoding device according to Embodiment 1. The image encoding device 2600 illustrated in FIG. 3A includes a transforming unit 2601 and a quantizing unit 2602. The image encoding device 2600 encodes an image for each block.

FIG. 3B is a flowchart showing processing of the image encoding device 2600 shown in FIG. 3A. First, the conversion unit 2601 converts a plurality of pixel values included in a block into a plurality of frequency coefficients (S2601). Next, the quantization unit 2602 quantizes a plurality of frequency coefficients using a parameter set determined for each block (S2602).

This encodes the image. In addition, since a parameter set determined for each block is used, deterioration of image quality is suppressed, and encoding efficiency is improved. The parameter set may include a quantization scaling matrix or a quantization offset matrix.

FIG. 4A is a configuration diagram illustrating the image decoding apparatus according to Embodiment 1. The image decoding device 2700 illustrated in FIG. 4A includes an inverse quantization unit 2701 and an inverse transform unit 2702. The image decoding device 2700 decodes an image for each block.

FIG. 4B is a flowchart showing processing of the image decoding device 2700 shown in FIG. 4A. First, the inverse quantization unit 2701 inversely quantizes a plurality of frequency coefficients included in a block using a parameter set determined for each block (S2701). Next, the inverse conversion unit 2702 converts a plurality of frequency coefficients into a plurality of pixel values (S2702).

This will decode the image. In addition, since a parameter set determined for each block is used, deterioration in image quality is suppressed. In addition, an image encoded by the same method is appropriately decoded.

FIG. 5A is a configuration diagram showing a more specific example of the image coding apparatus according to Embodiment 1. An image encoding device 2100 illustrated in FIG. 5A includes a writing unit 2101, a size determining unit 2102, a transforming unit 2103, and a quantizing unit 2104.

FIG. 5B is a flowchart showing processing of the image encoding device 2100 shown in FIG. 5A. First, the writing unit 2101 writes a plurality of quantization scaling matrices and a plurality of quantization offset values corresponding to a plurality of block sizes in the header (S2101).

At this time, the writing unit 2101 writes the first quantization offset value corresponding to the first block size. The writing unit 2101 writes the first quantization scaling matrix corresponding to the first block size.

Further, the writing unit 2101 writes a second quantization offset value corresponding to a second block size smaller than the first block size and larger than the first quantization offset value. The writing unit 2101 writes a second quantization scaling matrix that is a second quantization scaling matrix corresponding to the second block size and is smaller than the first quantization scaling matrix.

Here, the second quantization scaling matrix is smaller than the first quantization scaling matrix means that the plurality of scaling values included in the second quantization scaling matrix are more than the plurality of scaling values included in the first quantization scaling matrix. Also refers to being small as a whole. For the comparison of the quantized scaling matrices, an average value of a plurality of scaling values may be used, or a median value of the plurality of scaling values may be used. The same applies when comparing the size of the quantization offset matrix.

The size determining unit 2102 determines the block size (S2102). At this time, the size determining unit 2102 may calculate a distortion cost indicating the magnitude of distortion generated by quantization, and may determine the block size depending on the calculated distortion cost. Alternatively, the size determining unit 2102 may detect an edge in the image and determine the block size depending on the detected edge.

The conversion unit 2103 converts a plurality of pixel values included in a block formed with the determined block size into a plurality of frequency coefficients (S2103). Next, the quantization unit 2104 quantizes a plurality of frequency coefficients using a parameter set determined for each block (S2104). Here, the quantization unit 2104 uses a quantization scaling matrix corresponding to the block size as a parameter set. Also, the quantization unit 2104 uses a quantization offset value corresponding to the block size as a parameter set.

This encodes the image. A large quantization scaling matrix and a small quantization offset value are applied to a large block. This increases the coding efficiency of larger blocks. In addition, a small quantization scaling matrix and a large quantization offset value are applied to a small block. In addition, the image quality of smaller blocks is subjectively improved.

Typically, a large block is used for the flat part of the image, and a small block is used for the complex part of the image. The image encoding device 2100 applies a quantization scaling matrix and a quantization offset value according to the feature of such a block. Therefore, deterioration in image quality is suppressed and coding efficiency is improved.

FIG. 6 is a configuration diagram illustrating an example of a more specific image encoding device according to the first embodiment. 6 includes a calculation unit 400, a writing unit 402, a distortion calculation unit 404, a transform block size selection unit 406, a subtraction unit 408, a transform unit 410, a quantization unit 412, and an inverse quantization. Unit 414, inverse transform unit 416, memory unit 418, addition unit 422, and sample prediction unit 420.

The subtraction unit 408, the conversion unit 410, the quantization unit 412, the inverse quantization unit 414, the inverse conversion unit 416, the memory unit 418, the addition unit 422, and the sample prediction unit 420 form a part of the image encoding device 450. .

The calculation unit 400 reads a parameter set D401 that includes a plurality of predefined quantization scaling matrices and a plurality of predefined offset values, and a parameter set that includes the selected plurality of quantization scaling matrices and a plurality of offset values. D403 is output to the writing unit 402. Thereafter, the writing unit 402 writes the parameter set D405 including the plurality of selected quantization scaling matrices and the plurality of offset values in the picture header or the sequence header.

The distortion calculation unit 404 reads the image sample D409 of the block and the prediction sample D423 of the block, and outputs the cost value D408 to the transform block size selection unit 406. The transform block size selection unit 406 selects the transform block size D410 from the transform block size set based on the lowest distortion cost.

The subtraction unit 408 obtains a non-compressed image sample D409 and a prediction sample D423 of the picture, and outputs a residual block D411. Then, the transform unit 410 transforms the residual block D411 using the selected transform block size D410, and outputs the coefficient block D413 to the quantization unit 412. The quantization unit 412 reads the coefficient block D413 and the parameter set D407 including the plurality of selected quantization scaling matrices and the plurality of quantization offset values, and outputs a coded sample D415 of the picture.

The inverse quantization unit 414 reads the encoded sample D415, performs an inverse quantization process using the parameter set D407 including a plurality of selected quantization scaling matrices and a plurality of quantization offset values, and performs an inverse quantization coefficient D417. Is output to the inverse transform unit 416. The inverse transform unit 416 then outputs a reconstructed residual block D419. Thereafter, the adding unit 422 reads the reconstructed residual block D419 and the prediction sample D423, and outputs the reconstructed sample D425 of the picture.

The reconstructed sample D425 is then stored in the memory unit 418. The sample prediction unit reads the reconstructed sample D421 from the memory unit 418, and outputs the prediction sample D423.

FIG. 7 is a flowchart showing processing of the image encoding device 450 shown in FIG. As shown in this figure, the calculation unit 400 sets a smaller quantization offset value for a coefficient having a large transform block size (S200). In addition, the calculation unit 400 sets a larger quantization scaling matrix for the coefficients having the same large transform block size (S202).

The calculation unit 400 sets a larger quantization offset value for a smaller block size (S204). The calculation unit 400 sets a smaller quantization scaling matrix for a smaller transform block size (S206).

The writing unit 402 encodes a plurality of quantization offset values selected for a plurality of various transform sizes in the header (S208). The writing unit 402 encodes a plurality of quantization scaling matrices selected for a plurality of various transform sizes in the header (S210).

Next, the transform block size selection unit 406 selects a transform block size suitable for encoding the residual block from a group of transform block sizes based on the lowest distortion cost (S212). The conversion unit 410 converts the residual block using the selected conversion size (S214).

The quantization unit 412 quantizes the transform coefficient using the corresponding quantization offset value and scaling matrix based on the selected transform block size (S216). Similarly, the inverse quantization unit 414 inversely quantizes the quantization coefficient using the corresponding quantization offset value and scaling matrix based on the selected transform block size (S218).

The inverse transform unit 416 inversely transforms the coefficients using the selected transform block size to obtain a residual (S220). Finally, the adding unit 422 reconstructs the image sample by adding the prediction sample to the reconstructed residual (S222).

FIG. 8 is a block diagram showing a modification of the image encoding device 450 shown in FIG. 8 includes a calculation unit 500, a writing unit 502, an edge detection unit 504, a transform block size selection unit 506, a subtraction unit 508, a transform unit 510, a quantization unit 512, and an inverse quantization. Unit 514, inverse transform unit 516, memory unit 518, addition unit 522, and sample prediction unit 520.

The subtraction unit 508, the conversion unit 510, the quantization unit 512, the inverse quantization unit 514, the inverse conversion unit 516, the memory unit 518, the addition unit 522, and the sample prediction unit 520 form part of the image encoding device 550. .

The calculation unit 500 reads a parameter set D501 including a plurality of predefined quantization scaling matrices and a plurality of predefined offset values, and a parameter set including a plurality of selected quantization scaling matrices and a plurality of offset values. D503 is output to the writing unit 502. Then, the writing unit 502 writes the parameter set D505 including the plurality of selected quantization scaling values and the plurality of offset values in the picture header or sequence header.

The edge detection unit 504 reads the block image sample D509 and outputs the edge information D508 to the conversion block size selection unit 506. The transform block size selection unit 506 selects a transform block size D510 from the set of transform block sizes based on the edge information.

The subtraction unit 508 acquires the uncompressed image sample D509 and the prediction sample D523 of the picture, and outputs a residual block D511. Then, the transform unit 510 transforms the residual block D511 using the selected transform block size D510, and outputs the coefficient block D513 to the quantization unit 512. The quantization unit 512 reads the coefficient block D513 and the parameter set D507 including a plurality of selected quantization scaling matrices and a plurality of quantization offset values, and outputs a coded sample D515 of a picture.

The inverse quantization unit 514 reads the encoded sample D515, performs an inverse quantization process using the parameter set D507 including a plurality of selected quantization scaling matrices and a plurality of quantization offset values, and performs an inverse quantization coefficient D517. Is output to the inverse transform unit 516. The inverse transform unit then outputs a reconstructed residual block D519. Thereafter, the adder 522 reads the reconstructed residual block D519 and the prediction sample D523, and outputs the reconstructed sample D525 of the picture.

The reconstructed sample D525 is then stored in the memory unit 518. The sample prediction unit reads the reconstructed sample D521 from the memory unit 518, and outputs the prediction sample D523.

FIG. 9 is a flowchart showing processing of the image encoding device 550 shown in FIG. As shown in this figure, the calculation unit 500 sets a smaller quantization offset value for a coefficient having a large transform block size (S300). In addition, the calculation unit 500 sets a larger quantization scaling matrix for the coefficient having the same large transform block size (S302).

The calculation unit 500 sets a larger quantization offset value for a smaller block size (S304). The calculation unit 500 sets a smaller quantization scaling matrix for a smaller transform block size (S306).

The writing unit 502 encodes a plurality of quantization offset values selected for a plurality of various transform sizes in the header (S308). The writing unit 502 encodes a plurality of quantization scaling matrices selected for a plurality of various transform sizes in the header (S310).

Next, the transform block size selection unit 506 selects a transform block size suitable for encoding the residual block from a group of transform block sizes based on edge detection in the image sample block (S312). If the image sample block has an edge, a smaller transform block size is selected according to the position of the edge. The conversion unit 510 converts the residual block using the selected conversion size (S314).

The quantization unit 512 quantizes the transform coefficient using the corresponding quantization offset value and scaling matrix based on the selected transform block size (S316). Similarly, the inverse quantization unit 514 inversely quantizes the quantization coefficient using the corresponding quantization offset value and scaling matrix based on the selected transform block size (S318).

The inverse transform unit 516 transforms coefficients using the selected transform block size to obtain a residual (S320). Finally, the addition unit 522 reconstructs the image sample by adding the reconstructed residual to the prediction sample (S322).

As described above, the image encoding device and the image decoding device according to Embodiment 1 use a parameter set determined for each block. The image encoding apparatus may select an appropriate block size according to the characteristics of the image and apply an optimum parameter set according to the selected block size. Thereby, deterioration of image quality is suppressed and encoding efficiency is improved.

(Embodiment 2)
FIG. 10 is a conceptual diagram showing the relationship between the quantization scaling matrix and the inverse quantization value. As shown in this figure, the quantization scaling matrix is usually set small for low frequencies and large for high frequencies. This kind of setting usually improves the image quality subjectively.

The rate of increase of the quantization scaling matrix can be defined as the slope of the quantization scaling matrix. That is, the slope of the quantization scaling matrix indicates the rate of change in the quantization scaling value with respect to the change in frequency in the quantization scaling matrix. The quantization scaling matrix can directly control the quantization step size as shown in this figure.

FIG. 11 is a conceptual diagram showing the relationship between the quantization offset matrix and the inverse quantization value. As shown in this figure, the quantization offset matrix is usually set large for low frequencies and small for high frequencies. This kind of setting usually improves the image quality subjectively.

Quantization offset matrix decrease rate (increase rate in the negative direction) can be defined as the slope of the quantization offset matrix. That is, the slope of the quantization offset matrix indicates the rate of change in the quantization offset value with respect to the change in frequency in the quantization offset matrix. The quantization offset matrix can directly control the quantization offset adjustment as shown in this figure. This figure shows an example in which the quantization step size is the same for all frequency components.

FIG. 12A is a configuration diagram illustrating an image encoding device according to Embodiment 2. 12A includes a quantization parameter determination unit 2201, a matrix determination unit 2202, a matrix correction unit 2203, a conversion unit 2204, and a quantization unit 2205. The image encoding device 2200 illustrated in FIG.

FIG. 12B is a flowchart showing processing of the image encoding device 2200 shown in FIG. 12A. First, the quantization parameter determination unit 2201 determines a quantization parameter corresponding to a block (S2201). Next, the matrix determination unit 2202 determines a quantization scaling matrix corresponding to the block (S2202). Next, the matrix correction unit 2203 corrects the inclination of the quantization scaling matrix by correcting the quantization scaling matrix depending on the quantization parameter (S2203).

Here, when the quantization parameter is the second quantization parameter larger than the first quantization parameter, the matrix correction unit 2203 has a steeper slope than when the quantization parameter is the first quantization parameter. In addition, the quantization scaling matrix may be modified.

Next, the conversion unit 2204 converts a plurality of pixel values included in the block into a plurality of frequency coefficients (S2204). Finally, the quantization unit 2205 quantizes the plurality of frequency coefficients using the modified quantization scaling matrix and the determined quantization parameter (S2205).

Thereby, the image encoding device 2200 can encode the image. Also, the image encoding device 2200 can flexibly modify the quantization scaling matrix according to the quantization parameter. Therefore, the image encoding apparatus 2200 can determine the quantization scale step by the modified quantization scaling matrix more flexibly than determining the quantization scale step by multiplying the quantization parameter and the quantization scaling matrix. Can do.

For example, when the quantization parameter is large, the image encoding device 2200 may correct the inclination of the quantization scaling matrix by correcting the high-frequency scaling value in the quantization scaling matrix to a large value. Thereby, the image coding apparatus 2200 can improve coding efficiency.

Conversely, when the quantization parameter is small, the image encoding device 2200 may correct the inclination of the quantization scaling matrix by correcting the low-frequency scaling value in the quantization scaling matrix to a small value. Thereby, the image coding apparatus 2200 can improve the image quality.

In the above, an example of the quantization scaling matrix is shown, but the same applies to the quantization offset matrix. That is, first, the quantization parameter determination unit 2201 determines a quantization parameter corresponding to a block (S2201). Next, the matrix determination unit 2202 determines a quantization offset matrix corresponding to the block (S2202). Next, the matrix correction unit 2203 corrects the inclination of the quantization offset matrix by correcting the quantization offset matrix depending on the quantization parameter (S2203).

Here, when the quantization parameter is the second quantization parameter larger than the first quantization parameter, the matrix correction unit 2203 has a steeper slope than when the quantization parameter is the first quantization parameter. In addition, the quantization offset matrix may be modified.

Next, the conversion unit 2204 converts a plurality of pixel values included in the block into a plurality of frequency coefficients (S2204). Finally, the quantization unit 2205 quantizes the plurality of frequency coefficients using the modified quantization offset matrix and the determined quantization parameter (S2205).

Thereby, the image encoding device 2200 can encode the image. Further, the image encoding device 2200 can flexibly modify the quantization offset matrix according to the quantization parameter. Therefore, the image coding apparatus 2200 can determine the adjustment amount with the modified quantization offset matrix more flexibly than the adjustment amount is determined by multiplying the quantization parameter and the quantization offset matrix.

For example, when the quantization parameter is large, the image encoding device 2200 may correct the gradient of the quantization offset matrix by correcting the high-frequency offset value in the quantization offset matrix to a small value. Thereby, the image coding apparatus 2200 can improve coding efficiency.

Conversely, when the quantization parameter is small, the image encoding device 2200 may correct the slope of the quantization offset matrix by correcting the low-frequency offset value in the quantization offset matrix to a large value. Thereby, the image coding apparatus 2200 can improve the image quality.

Note that the quantization parameter determined by the quantization parameter determination unit 2201 may be a predetermined quantization parameter. Similarly, the quantization matrix determined by the matrix determination unit 2202 may be a predetermined quantization matrix. In this case, the matrix correction unit 2203 corrects a predetermined inclination of the quantization matrix.

In addition, even when the inclination of the quantization matrix determined by the matrix determination unit 2202 is flat, the matrix correction unit 2203 can set the inclination of the quantization matrix depending on the quantization parameter.

FIG. 13A is a configuration diagram illustrating an image decoding apparatus according to Embodiment 2. 13A includes a quantization parameter determination unit 2301, a matrix determination unit 2302, a matrix modification unit 2303, an inverse quantization unit 2304, and an inverse transform unit 2305.

FIG. 13B is a flowchart showing processing of the image decoding device 2300 shown in FIG. 13A. First, the quantization parameter determination unit 2301 determines a quantization parameter corresponding to a block (S2301). Next, the matrix determination unit 2302 determines a quantization scaling matrix corresponding to the block (S2302). Next, the matrix correction unit 2303 corrects the inclination of the quantization scaling matrix by correcting the quantization scaling matrix depending on the quantization parameter (S2303).

Here, when the quantization parameter is the second quantization parameter larger than the first quantization parameter, the matrix correction unit 2303 has a steeper slope than when the quantization parameter is the first quantization parameter. In addition, the quantization scaling matrix may be modified.

Next, the inverse quantization unit 2304 inversely quantizes a plurality of frequency coefficients using the modified quantization scaling matrix and the determined quantization parameter (S2304). Finally, the inverse transform unit 2305 transforms a plurality of frequency coefficients included in the block into a plurality of pixel values (S2305).

Thereby, the image decoding device 2300 can decode the image. Further, the image decoding device 2300 can flexibly modify the quantization scaling matrix according to the quantization parameter. Therefore, the image decoding apparatus 2300 can determine the quantization scale step more flexibly by using the modified quantization scaling matrix, rather than multiplying the quantization parameter and the quantization scaling matrix to determine the quantization scale step. it can.

In addition, the image decoding device 2300 modifies the quantization scaling matrix so as to be the same as the quantization scaling matrix modified by the image encoding device 2200, thereby converting the image encoded by the image encoding device 2200. It can be decoded properly.

In the above, an example of the quantization scaling matrix is shown, but the same applies to the quantization offset matrix. That is, first, the quantization parameter determination unit 2301 determines a quantization parameter corresponding to a block (S2301). Next, the matrix determination unit 2302 determines a quantization offset matrix corresponding to the block (S2302). Next, the matrix correction unit 2303 corrects the inclination of the quantization offset matrix by correcting the quantization offset matrix (S2303).

Here, when the quantization parameter is the second quantization parameter larger than the first quantization parameter, the matrix correction unit 2303 has a steeper slope than when the quantization parameter is the first quantization parameter. In addition, the quantization offset matrix may be modified.

Next, the inverse quantization unit 2304 inversely quantizes a plurality of frequency coefficients using the modified quantization offset matrix and the determined quantization parameter (S2304). Finally, the inverse transform unit 2305 transforms a plurality of frequency coefficients included in the block into a plurality of pixel values (S2305).

Thereby, the image decoding device 2300 can decode the image. Further, the image decoding apparatus 2300 can flexibly modify the quantization offset matrix according to the quantization parameter. Therefore, the image decoding apparatus 2300 can determine the adjustment amount flexibly with the modified quantization offset matrix more flexibly than determining the adjustment amount by multiplying the quantization parameter and the quantization offset matrix.

Further, the image decoding apparatus 2300 corrects the image encoded by the image encoding apparatus 2200 by correcting the quantization offset matrix so as to be the same as the quantization offset matrix corrected by the image encoding apparatus 2200. It can be decoded properly. Also, the same quantization offset matrix may not be used for quantization and inverse quantization. Therefore, the image decoding device 2300 may flexibly modify the quantization offset matrix regardless of the processing in the image coding device 2200.

Note that the quantization parameter determined by the quantization parameter determination unit 2301 may be a predetermined quantization parameter. Similarly, the quantization matrix determined by the matrix determination unit 2302 may be a predetermined quantization matrix. In this case, the matrix correction unit 2303 corrects a predetermined inclination of the quantization matrix.

In addition, even when the inclination of the quantization matrix determined by the matrix determination unit 2302 is flat, the matrix correction unit 2303 can set the inclination of the quantization matrix depending on the quantization parameter.

FIG. 14 is a configuration diagram illustrating a more specific example of the image encoding device according to the second embodiment. 14 includes a quantization matrix correction unit 1200, a subtraction unit 1202, a conversion unit 1204, a quantization unit 1206, an inverse quantization unit 1208, an inverse conversion unit 1212, a memory unit 1214, and an addition unit. 1216 and a sample prediction unit 1210.

The subtraction unit 1202, the conversion unit 1204, the quantization unit 1206, the inverse quantization unit 1208, the inverse conversion unit 1212, the memory unit 1214, the addition unit 1216, and the sample prediction unit 1210 form part of the image encoding device 1250. .

The quantization matrix correction unit 1200 reads the quantization scaling matrix D1201, the quantization offset matrix D1203, or both the quantization scaling matrix D1201 and the quantization offset matrix D1203. Further, the quantization matrix correction unit 1200 reads the quantization parameter D1205 and outputs the corrected quantization matrix D1217 to both the quantization unit 1206 and the inverse quantization unit 1208.

The subtraction unit 1202 acquires a non-compressed image sample D1207 and a prediction sample D1213 of a picture, and outputs a residual block D1209. Then, the transform unit 1204 transforms the residual block D1209 and outputs the coefficient block D1211 to the quantization unit 1206. The quantization unit 1206 reads the coefficient block D1211, the quantization parameter D1205, and the corrected quantization matrix D1217, and outputs a coded sample D1215 of the picture.

The inverse quantization unit 1208 reads the encoded sample D1215, performs an inverse quantization process using the quantization parameter D1205 and the corrected quantization matrix D1217, and outputs the inverse quantization coefficient D1219 to the inverse transform unit 1212. . The inverse transform unit then outputs a reconstructed residual block D1221. Thereafter, the adder 1216 reads the reconstructed residual block D1221 and the prediction sample D1213, and outputs a reconstructed sample D1225 of the picture.

The reconstructed sample D1225 is then stored in the memory unit 1214. The sample prediction unit reads the reconstructed sample D1223 from the memory unit 1214, and outputs the prediction sample D1213.

FIG. 15 is a flowchart showing a first example of processing executed by the image encoding device 1250 shown in FIG. First, a quantization parameter determination unit (not shown in FIG. 14) determines a quantization parameter for a transform coefficient block (S800). The quantization step size for each coefficient is controlled by both the quantization parameter and the quantization scaling matrix. The quantization parameter controls the quantization step size for all the coefficients of the block.

Next, the matrix determination unit (not shown in FIG. 14) determines a quantization scaling matrix for the block (S802). Then, the quantization matrix correcting unit 1200 corrects the inclination of the quantization scaling matrix according to the quantization parameter of the block (S804). For example, if the value of the quantization parameter is large, the gradient of the quantization scaling matrix becomes steep, and the gradient becomes gentle as the quantization parameter becomes small.

Then, the quantization unit 1206 performs a quantization process using the corrected scaling matrix and the quantization parameter (S806). The inverse quantization unit 1208 executes the inverse quantization process using the corrected quantization scaling matrix and the quantization parameter (S808).

FIG. 16 is a flowchart showing a second example of processing executed by the image encoding device 1250 shown in FIG. First, a quantization parameter determination unit (not shown in FIG. 14) determines a quantization parameter for a transform coefficient block (S900). The quantization parameter controls the quantization step size for all coefficients of the block, and the quantization offset matrix controls the inverse quantization adjustment.

Next, the matrix determination unit (not shown in FIG. 14) determines a quantization offset matrix for the block (S902). Then, the quantization matrix correction unit 1200 corrects the inclination of the quantization offset matrix according to the quantization parameter of the block (S904). For example, if the value of the quantization parameter is large, the inclination of the quantization offset matrix becomes steep, and the inclination becomes gentle as the quantization parameter becomes small.

Then, the quantization unit 1206 performs a quantization process using the corrected offset matrix and the quantization parameter (S906). The inverse quantization unit 1208 executes the inverse quantization process using the corrected quantization offset matrix and the quantization parameter (S908).

FIG. 17 is a configuration diagram showing a more specific example of the image decoding apparatus according to the second embodiment. The image decoding apparatus 1350 illustrated in FIG. 17 includes a quantization matrix correction unit 1300, an inverse quantization unit 1302, an inverse transform unit 1304, a sample reconstruction unit 1306, a sample prediction unit 1308, and a memory unit 1310.

The inverse quantization unit 1302, the inverse transform unit 1304, the sample reconstruction unit 1306, the memory unit 1310, and the sample prediction unit 1308 form part of the image decoding device 1350.

The quantization matrix correction unit 1300 reads the quantization scaling matrix D1301, the quantization offset matrix D1303, or both the quantization scaling matrix D1301 and the quantization offset matrix D1303. Also, the quantization matrix correction unit 1300 reads the quantization parameter D1305 and outputs the corrected quantization matrix D1319 to the inverse quantization unit 1302.

The inverse quantization unit 1302 reads the coded block D1307 of the picture, performs an inverse quantization process using the quantization parameter D1305 and the modified quantization matrix D1319, and sends the inverse quantization coefficient D1309 to the inverse transform unit 1304. Output. The inverse transform unit 1304 then outputs the decoded residual block D1311 to the sample reconstruction unit 1306. The sample reconstruction unit 1306 acquires the decoded residual block D1311 and the prediction sample D1313, and outputs the reconstruction sample D1315.

The reconstructed sample D1315 is then stored in the memory unit 1310. The sample prediction unit 1308 reads the reconstructed sample D1317 from the memory unit 1310, and outputs the prediction sample D1313.

FIG. 18 is a flowchart showing a first example of processing executed by the image decoding apparatus shown in FIG. The quantization parameter determination unit (not shown in FIG. 17) determines the quantization parameter for the transform coefficient block (S1000). This parameter is usually parsed from the picture header or block header. The quantization step size for each coefficient is controlled by both the quantization parameter and the quantization scaling matrix. The quantization parameter controls the quantization step size for all the coefficients of the block.

Next, the matrix determination unit (not shown in FIG. 17) determines a quantization scaling matrix for the block (S1002). Then, the quantization matrix correction unit 1300 corrects the inclination of the quantization scaling matrix according to the quantization parameter of the block (S1004). For example, if the value of the quantization parameter is large, the gradient of the quantization scaling matrix becomes steep, and the gradient becomes gentle as the quantization parameter becomes small.

Then, the inverse quantization unit 1302 executes an inverse quantization process using the modified quantization scaling matrix and the quantization parameter (S1006).

FIG. 19 is a flowchart showing a second example of processing executed by the image decoding apparatus shown in FIG. The quantization parameter determination unit (not shown in FIG. 17) determines the quantization parameter for the transform coefficient block (S1100). This parameter is usually parsed from the picture header or block header. The quantization parameter controls the quantization step size for all coefficients of the block, and the quantization offset matrix controls the inverse quantization adjustment.

Next, the matrix determination unit (not shown in FIG. 17) determines a quantization offset matrix for the block (S1102). Then, the quantization matrix correction unit 1300 corrects the inclination of the quantization offset matrix according to the quantization parameter of the block (S1104). For example, if the value of the quantization parameter is large, the inclination of the quantization offset matrix becomes steep, and the inclination becomes gentle as the quantization parameter becomes small.

Then, the inverse quantization unit 1302 executes an inverse quantization process using the corrected quantization offset matrix and the quantization parameter (S1106).

As described above, the image encoding device and the image decoding device according to Embodiment 2 use a parameter set determined for each block. Then, the image encoding device and the image decoding device flexibly modify the quantization scaling matrix or the quantization offset matrix according to the quantization parameter. Thereby, deterioration of image quality is suppressed and encoding efficiency is improved.

(Embodiment 3)
FIG. 20A is a configuration diagram illustrating an image encoding device according to Embodiment 3. 20A includes a first writing unit 2401, a selection unit 2402, a second writing unit 2403, a conversion unit 2404, and a quantization unit 2405.

FIG. 20B is a flowchart showing processing of the image encoding device 2400 shown in FIG. 20A. First, the first writing unit 2401 writes the first quantization offset matrix in the header (S2401). Next, the selection unit 2402 selects a quantization offset matrix from the first quantization offset matrix and a predetermined second quantization offset matrix different from the first quantization offset matrix (S2402).

Next, when the second quantization offset matrix is selected, the second writing unit 2403 writes a flag indicating a predetermined value in the block header (S2403). Next, the conversion unit 2404 converts a plurality of pixel values included in the block into a plurality of frequency coefficients (S2404). Finally, the quantization unit 2405 quantizes the plurality of frequency coefficients using the selected quantization offset matrix (S2405).

Thereby, the image encoding device 2400 can encode the image. Also, the image encoding device 2400 can switch between a customized first quantization offset matrix and a predetermined second quantization offset matrix. The image encoding device 2400 can notify the decoding side of the selected quantization offset matrix while suppressing an increase in the amount of data generated by encoding.

FIG. 21A is a block diagram showing an image decoding apparatus according to Embodiment 3. An image decoding apparatus 2500 shown in FIG. 21A includes a first analysis unit 2501, a second analysis unit 2502, a selection unit 2503, an inverse quantization unit 2504, and an inverse transform unit 2505.

FIG. 21B is a flowchart showing processing of the image decoding device 2500 shown in FIG. 21A.

First, the first analysis unit 2501 acquires the first quantization offset matrix by analyzing the header (S2501). Next, the second analysis unit 2502 obtains a flag by analyzing the block header (S2502).

Here, when the acquired flag indicates a predetermined value, the selection unit 2503 selects a predetermined second quantization offset matrix different from the first quantization offset matrix. On the other hand, when the acquired flag does not indicate a predetermined value, the selection unit 2503 selects the first quantization offset matrix (S2503).

Next, the inverse quantization unit 2504 inversely quantizes the plurality of frequency coefficients using the selected first quantization offset matrix or the selected second quantization offset matrix (S2504). Finally, the inverse conversion unit 2505 converts a plurality of frequency coefficients included in the block into a plurality of pixel values (S2505).

Thereby, the image decoding device 2500 can decode the image. In addition, the image decoding device 2500 can switch between the customized first quantization offset matrix and a predetermined second quantization offset matrix. Then, the image decoding apparatus 2500 can select an appropriate quantization offset matrix based on the flag set on the encoding side.

FIG. 22 is a diagram showing the position of the matrix selection flag stored in the coding block according to the third embodiment. The matrix selection flag D1602 shown in FIG. 16 is stored in the header of the coding block of the picture D1600. The customized quantization offset matrix may be stored in the picture header or in the sequence header of the bitstream.

FIG. 23 is a configuration diagram illustrating a specific example of the image encoding device according to the third embodiment. The image encoding device 1450 illustrated in FIG. 23 includes a quantization offset matrix selection unit 1400, a first writing unit 1418, a second writing unit 1420, a subtraction unit 1402, a conversion unit 1404, a quantization unit 1406, an inverse quantum A conversion unit 1408, an inverse conversion unit 1412, a memory unit 1414, an addition unit 1416, and a sample prediction unit 1410.

The subtraction unit 1402, the conversion unit 1404, the quantization unit 1406, the inverse quantization unit 1408, the inverse conversion unit 1412, the memory unit 1414, the addition unit 1416, and the sample prediction unit 1410 form part of the image encoding device 1450.

The quantization offset matrix selection unit 1400 reads a customizable quantization offset matrix D1403 and a predetermined quantization offset matrix D1401. Then, the quantization offset matrix selection unit 1400 selects the quantization offset matrix, and outputs the selected quantization offset matrix D1417 to the quantization unit 1406 and the inverse quantization unit 1408.

The first writing unit 1418 reads the customizable quantization offset matrix D1403, and writes the customizable quantization offset matrix D1427 in the picture header or sequence header. The second writing unit 1420 reads the matrix selection flag D1405 from the quantization offset matrix selection unit 1400, and writes the matrix selection flag D1429 in the encoded block header.

The subtraction unit 1402 acquires a non-compressed image sample D1407 and a prediction sample D1413 of the picture, and outputs a residual block D1409. Subsequently, the transform unit 1404 transforms the residual block D1409 and outputs the coefficient block D1411 to the quantization unit 1406. The quantization unit 1406 reads the coefficient block D1411, and the selected quantization offset matrix D1417, and outputs a coded sample D1415 of the picture.

The inverse quantization unit 1408 reads the encoded sample D1415 and executes an inverse quantization process using the selected quantization offset matrix D1417. Then, the inverse quantization unit 1408 outputs the inverse quantization coefficient D1419 to the inverse transform unit 1412. The inverse transform unit 1412 then outputs a reconstructed residual block D1421. Thereafter, the adding unit 1416 reads the reconstructed residual block D1421 and the prediction sample D1413, and outputs a reconstructed sample D1425 of the picture.

The reconstructed sample D1425 is then stored in the memory unit 1414. The sample prediction unit 1410 reads the reconstructed sample D1423 from the memory unit 1414, and outputs the prediction sample D1413.

FIG. 24 is a flowchart showing processing of the image encoding device 1450 shown in FIG. First, the first writing unit 1418 encodes a customizable quantization offset matrix and writes the encoded quantization offset matrix in the header (S1800).

Next, the quantization offset matrix selection unit 1400 determines whether or not to use a predetermined quantization offset matrix (S1802). If the quantization offset matrix selection unit 1400 determines to use a predetermined quantization offset matrix (Yes in S1802), the quantization offset matrix selection unit 1400 selects a predetermined quantization matrix (S1804). In this case, the second writing unit 1420 writes a flag indicating a predetermined value in the header of the encoded block (S1807).

If the quantization offset matrix selection unit 1400 determines not to use a predetermined quantization offset matrix (No in S1802), the quantization offset matrix selection unit 1400 selects the quantization offset matrix that has been encoded and written in the header (S1806). . The quantization offset matrix may be written in either the sequence header or the picture header. Then, the quantization unit 1406 performs a quantization process using the selected quantization offset matrix (S1808). Finally, the inverse quantization unit 1408 executes the inverse quantization process using the selected quantization offset matrix (S1810).

FIG. 25 is a configuration diagram illustrating a specific example of the image decoding apparatus according to the third embodiment. The image decoding apparatus 1550 shown in FIG. 25 includes a first analysis unit 1512, a second analysis unit 1514, a quantization offset matrix selection unit 1500, an inverse quantization unit 1502, an inverse transform unit 1504, a sample reconstruction unit 1506, a sample A prediction unit 1508, a first memory unit 1510, and a second memory unit 1516 are provided.

The inverse quantization unit 1502, the inverse transform unit 1504, the sample reconstruction unit 1506, the first memory unit 1510, and the sample prediction unit 1508 form a part of the image decoding device 1550.

The first analysis unit 1512 reads a picture header or a sequence header, and outputs a quantization offset matrix D1503 to the quantization offset matrix selection unit 1500. The second analysis unit 1514 reads the encoded block header and outputs a matrix selection flag D1505 to the quantization offset matrix selection unit 1500.

The quantization offset matrix selection unit 1500 reads the matrix selection flag D1505, and selects a predetermined quantization offset matrix D1501 or the analyzed quantization offset matrix D1503 from the second memory unit 1516. Then, the quantization offset matrix selection unit 1500 outputs the selected quantization offset matrix D1519 to the inverse quantization unit 1502.

The inverse quantization unit 1502 acquires the picture coding block D1507, performs inverse quantization processing using the selected quantization offset matrix D1519, and outputs the inverse quantization coefficient D1509 to the inverse transform unit 1504. . Thereafter, the inverse transform unit 1504 outputs the residual block D1511 to the sample reconstruction unit 1506. The sample reconstruction unit 1506 acquires the residual block D1511 and the prediction sample D1513, and outputs the reconstruction sample D1515.

The reconstructed sample D1515 is then stored in the first memory unit 1510. The sample prediction unit 1508 acquires the reconstructed sample D1517 from the first memory unit 1510, and outputs the prediction sample D1513.

FIG. 26 is a flowchart showing processing of the image decoding apparatus 1550 shown in FIG. First, the first analysis unit 1512 analyzes the header of the encoded block and acquires a flag (S1700). Next, the quantization offset matrix selection unit 1500 determines whether or not the flag indicates a predetermined value (S1702). When the flag indicates a predetermined value (Yes in S1702), the quantization offset matrix selection unit 1500 selects a predetermined quantization offset matrix (S1704).

When the flag does not indicate a predetermined value (No in S1702), the quantization offset matrix selection unit 1500 selects a decoded quantization offset matrix (S1706). The decoded quantization offset matrix is obtained by decoding the quantization offset matrix that has been encoded and written in the header. The quantization offset matrix written in the header may be written in either the sequence header or the picture header.

Finally, the inverse quantization unit 1502 executes an inverse quantization process using the selected quantization offset matrix (S1708).

As described above, the image encoding device and the image decoding device according to Embodiment 3 use a parameter set determined for each block. Then, the image encoding device and the image decoding device can switch between a predetermined quantization offset matrix and a customized quantization offset matrix. Thereby, deterioration of image quality is suppressed and encoding efficiency is improved.

As described above, as shown in a plurality of embodiments, the image encoding device and the image decoding device according to the present invention encode an image using a parameter set determined for each block. Thereby, deterioration of image quality is suppressed and encoding efficiency is improved.

Although the image encoding device and the image decoding device according to the present invention have been described based on the embodiments, the present invention is not limited to these embodiments. Unless it deviates from the meaning of the present invention, various forms conceived by those skilled in the art are applied to the embodiment, and other forms constructed by combining components and steps in different embodiments are also included in the present invention. It is included in the range.

The configurations and processes shown in the plurality of embodiments are examples, and the configurations or processes may be rearranged. For example, the order of the processes may be changed, or another component may execute a process executed by a specific component.

Further, the present invention can be realized not only as an image encoding device and an image decoding device, but also as a method using a processing means constituting the image encoding device or the image decoding device as a step. And this invention is realizable as a program which makes a computer perform these steps. Furthermore, the present invention can be realized as a computer-readable recording medium such as a CD-ROM storing the program.

(Embodiment 4)
By recording a program for realizing the configuration of the image encoding method or the image decoding method described in the above embodiment on a storage medium, the processing described in the above embodiment can be easily performed in an independent computer system. It becomes possible. The storage medium may be any medium that can record a program, such as a magnetic disk, an optical disk, a magneto-optical disk, an IC card, and a semiconductor memory.

Further, application examples of the image encoding method and the image decoding method shown in the above embodiment and a system using the same will be described here.

FIG. 27 is a diagram showing an overall configuration of a content supply system ex100 that realizes a content distribution service. The communication service providing area is divided into desired sizes, and base stations ex106 to ex110, which are fixed radio stations, are installed in each cell.

The content supply system ex100 includes a computer ex111, a PDA (Personal Digital Assistant) ex112, a camera ex113, a mobile phone ex114, a game machine via the Internet ex101, the Internet service provider ex102, the telephone network ex104, and the base stations ex106 to ex110. Each device such as ex115 is connected.

However, the content supply system ex100 is not limited to the configuration shown in FIG. 27, and may be connected by combining any of the elements. Further, each device may be directly connected to the telephone network ex104 without going through the base stations ex106 to ex110 which are fixed wireless stations. In addition, the devices may be directly connected to each other via short-range wireless or the like.

The camera ex113 is a device that can shoot moving images such as a digital video camera, and the camera ex116 is a device that can shoot still images and movies such as a digital camera. In addition, the mobile phone ex114 is a GSM (Global System for Mobile Communications) method, a CDMA (Code Division Multiple Access) method, a W-CDMA (Wideband-Code Division Multiple Access L (Semiconductor Access) method, a W-CDMA (Wideband-Code Division Multiple Access L method, or a high access rate). A High Speed Packet Access) mobile phone or a PHS (Personal Handyphone System) may be used.

In the content supply system ex100, the camera ex113 and the like are connected to the streaming server ex103 through the base station ex109 and the telephone network ex104, thereby enabling live distribution and the like. In the live distribution, the content (for example, music live video) captured by the user using the camera ex113 is encoded as described in the above embodiment and transmitted to the streaming server ex103. On the other hand, the streaming server ex103 streams the content data transmitted to the requested client. Examples of the client include a computer ex111, a PDA ex112, a camera ex113, a mobile phone ex114, a game machine ex115, and the like that can decode the encoded data. Each device that has received the distributed data decodes and reproduces the received data.

Note that the encoded processing of the captured data may be performed by the camera ex113, the streaming server ex103 that performs the data transmission processing, or may be performed in a shared manner. Similarly, the decryption processing of the distributed data may be performed by the client, the streaming server ex103, or may be performed in a shared manner. In addition to the camera ex113, still images and / or moving image data captured by the camera ex116 may be transmitted to the streaming server ex103 via the computer ex111. The encoding process in this case may be performed by any of the camera ex116, the computer ex111, and the streaming server ex103, or may be performed in a shared manner.

In addition, these encoding processing and decoding processing are generally performed in a computer ex111 and an LSI (Large Scale Integration) ex500 included in each device. The LSI ex500 may be configured as a single chip or a plurality of chips. Note that image encoding and image decoding software is incorporated into some recording medium (CD-ROM, flexible disk, hard disk, etc.) that can be read by the computer ex111 and the like, and the encoding processing and decoding processing are performed using the software. May be. Furthermore, when the mobile phone ex114 is equipped with a camera, moving image data acquired by the camera may be transmitted. The moving image data at this time is data encoded by the LSI ex500 included in the mobile phone ex114.

Further, the streaming server ex103 may be a plurality of servers or a plurality of computers, and may process, record, and distribute data in a distributed manner.

As described above, in the content supply system ex100, the encoded data can be received and reproduced by the client. As described above, in the content supply system ex100, the information transmitted by the user can be received, decrypted and reproduced in real time by the client, and even a user who does not have special rights or facilities can realize personal broadcasting.

The image encoding method or the image decoding method shown in the above embodiment may be used for encoding and decoding of each device constituting the content supply system.

As an example, a mobile phone ex114 will be described.

FIG. 28 is a diagram illustrating the mobile phone ex114 using the image encoding method and the image decoding method described in the above embodiment. The cellular phone ex114 includes an antenna ex601 for transmitting and receiving radio waves to and from the base station ex110, a video from a CCD camera, a camera unit ex603 capable of taking a still image, a video shot by the camera unit ex603, and an antenna ex601. A display unit ex602 such as a liquid crystal display that displays data obtained by decoding received video and the like, a main body unit composed of a group of operation keys ex604, an audio output unit ex608 such as a speaker for outputting audio, and a voice input Audio input unit ex605 such as a microphone, recorded moving image or still image data, received mail data, moving image data or still image data, etc., for storing encoded data or decoded data Recording media ex607 can be attached to media ex607 and mobile phone ex114 And a slot unit ex606 for. The recording medium ex607 stores a flash memory element, which is a kind of EEPROM, which is a nonvolatile memory that can be electrically rewritten and erased, in a plastic case such as an SD card.

Further, the cellular phone ex114 will be described with reference to FIG. The mobile phone ex114 has a power supply circuit ex710, an operation input control unit ex704, an image encoding unit, and a main control unit ex711 configured to control the respective units of the main body unit including the display unit ex602 and the operation key ex604. Unit ex712, camera interface unit ex703, LCD (Liquid Crystal Display) control unit ex702, image decoding unit ex709, demultiplexing unit ex708, recording / reproducing unit ex707, modulation / demodulation circuit unit ex706, and audio processing unit ex705 are connected to each other via a synchronization bus ex713. It is connected.

When the end of call and the power key are turned on by a user operation, the power supply circuit ex710 activates the camera-equipped digital mobile phone ex114 by supplying power to each unit from the battery pack. .

The cellular phone ex114 converts the audio signal collected by the audio input unit ex605 in the audio call mode into digital audio data by the audio processing unit ex705 based on the control of the main control unit ex711 including a CPU, a ROM, a RAM, and the like. The modulation / demodulation circuit unit ex706 performs spread spectrum processing, the transmission / reception circuit unit ex701 performs digital analog conversion processing and frequency conversion processing, and then transmits the result via the antenna ex601. Further, the cellular phone ex114 amplifies the received data received by the antenna ex601 in the voice call mode, performs frequency conversion processing and analog-digital conversion processing, performs spectrum despreading processing by the modulation / demodulation circuit unit ex706, and performs analog speech by the voice processing unit ex705. After the data is converted, it is output via the audio output unit ex608.

Further, when an e-mail is transmitted in the data communication mode, text data of the e-mail input by operating the operation key ex604 on the main body is sent to the main control unit ex711 via the operation input control unit ex704. The main control unit ex711 performs spread spectrum processing on the text data in the modulation / demodulation circuit unit ex706, performs digital analog conversion processing and frequency conversion processing in the transmission / reception circuit unit ex701, and then transmits the text data to the base station ex110 via the antenna ex601.

When transmitting image data in the data communication mode, the image data captured by the camera unit ex603 is supplied to the image encoding unit ex712 via the camera interface unit ex703. When image data is not transmitted, the image data captured by the camera unit ex603 can be directly displayed on the display unit ex602 via the camera interface unit ex703 and the LCD control unit ex702.

The image encoding unit ex712 is configured to include the image encoding device described in the present invention, and an encoding method using the image data supplied from the camera unit ex603 in the image encoding device described in the above embodiment. Is converted into encoded image data by compression encoding and sent to the demultiplexing unit ex708. At the same time, the mobile phone ex114 sends the sound collected by the sound input unit ex605 during imaging by the camera unit ex603 to the demultiplexing unit ex708 via the sound processing unit ex705 as digital sound data.

The demultiplexing unit ex708 multiplexes the encoded image data supplied from the image encoding unit ex712 and the audio data supplied from the audio processing unit ex705 by a predetermined method, and the resulting multiplexed data is a modulation / demodulation circuit unit Spread spectrum processing is performed in ex706, digital analog conversion processing and frequency conversion processing are performed in the transmission / reception circuit unit ex701, and then transmission is performed via the antenna ex601.

When data of a moving image file linked to a home page or the like is received in the data communication mode, the received data received from the base station ex110 via the antenna ex601 is subjected to spectrum despreading processing by the modulation / demodulation circuit unit ex706, and the resulting multiplexing is obtained. Data is sent to the demultiplexing unit ex708.

In addition, in order to decode multiplexed data received via the antenna ex601, the demultiplexing unit ex708 separates the multiplexed data into a bit stream of image data and a bit stream of audio data, and a synchronization bus The encoded image data is supplied to the image decoding unit ex709 via ex713 and the audio data is supplied to the audio processing unit ex705.

Next, the image decoding unit ex709 is configured to include the image decoding device described in the present application, and is reproduced by decoding the bit stream of the image data with a decoding method corresponding to the encoding method described in the above embodiment. Moving image data is generated and supplied to the display unit ex602 via the LCD control unit ex702, thereby displaying, for example, moving image data included in a moving image file linked to a home page. At the same time, the audio processing unit ex705 converts the audio data into analog audio data, and then supplies the analog audio data to the audio output unit ex608. Thus, for example, the audio data included in the moving image file linked to the home page is reproduced. The

Note that the present invention is not limited to the above-described system, and recently, digital broadcasting using satellites and terrestrial waves has become a hot topic. As shown in FIG. A decoding device can be incorporated. Specifically, in the broadcasting station ex201, audio data, video data, or a bit stream in which those data are multiplexed is transmitted to a communication or broadcasting satellite ex202 via radio waves. In response, the broadcasting satellite ex202 transmits a radio wave for broadcasting, and a home antenna ex204 having a satellite broadcasting receiving facility receives the radio wave, and the television (receiver) ex300 or the set top box (STB) ex217 or the like. The device decodes the bitstream and reproduces it. The reader / recorder ex218 that reads and decodes a bitstream in which image data and audio data recorded on recording media ex215 and ex216 such as CD and DVD as recording media are multiplexed is also shown in the above embodiment. It is possible to implement an image decoding device. In this case, the reproduced video signal is displayed on the monitor ex219. Further, a configuration in which an image decoding device is mounted in a set-top box ex217 connected to a cable ex203 for cable television or an antenna ex204 for satellite / terrestrial broadcasting, and this is reproduced on the monitor ex219 of the television is also conceivable. At this time, the image decoding apparatus may be incorporated in the television instead of the set top box. In addition, a car ex210 having an antenna ex205 can receive a signal from a satellite ex202 or a base station and reproduce a moving image on a display device such as a car navigation ex211 included in the car ex210.

Also, audio data, video data recorded on a recording medium ex215 such as DVD or BD, or an encoded bit stream in which those data are multiplexed are read and decoded, or audio data, video data or these are recorded on the recording medium ex215. The image decoding apparatus or the image encoding apparatus described in the above embodiment can also be mounted on the reader / recorder ex218 that encodes the data and records the multiplexed data as multiplexed data. In this case, the reproduced video signal is displayed on the monitor ex219. In addition, the recording medium ex215 on which the encoded bit stream is recorded allows other devices and systems to reproduce the video signal. For example, the other reproduction device ex212 can reproduce the video signal on the monitor ex213 using the recording medium ex214 on which the encoded bitstream is copied.

Also, an image decoding device may be mounted in the set-top box ex217 connected to the cable ex203 for cable television or the antenna ex204 for satellite / terrestrial broadcasting and displayed on the monitor ex219 of the television. At this time, the image decoding apparatus may be incorporated in the television instead of the set top box.

FIG. 31 is a diagram illustrating a television (receiver) ex300 that uses the image decoding method and the image encoding method described in the above embodiment. The television ex300 obtains or outputs a bit stream of video information via the antenna ex204 or the cable ex203 that receives the broadcast, and a tuner ex301 that outputs or outputs the encoded data that is received or demodulated. Modulation / demodulation unit ex302 that modulates data for transmission to the outside, and multiplexing / separation unit ex303 that separates demodulated video data and audio data, or multiplexes encoded video data and audio data Is provided. In addition, the television ex300 decodes each of the audio data and the video data, or encodes the respective information, the audio signal processing unit ex304, the signal processing unit ex306 including the video signal processing unit ex305, and the decoded audio signal. And an output unit ex309 including a display unit ex308 such as a display for displaying the decoded video signal. Furthermore, the television ex300 includes an interface unit ex317 including an operation input unit ex312 that receives an input of a user operation. Furthermore, the television ex300 includes a control unit ex310 that controls each unit in an integrated manner, and a power supply circuit unit ex311 that supplies power to each unit. In addition to the operation input unit ex312, the interface unit ex317 includes a bridge ex313 connected to an external device such as a reader / recorder ex218, a slot unit ex314 for enabling recording media ex216 such as an SD card, and an external recording such as a hard disk A driver ex315 for connecting to a medium, a modem ex316 for connecting to a telephone network, and the like may be included. The recording medium ex216 is capable of electrically recording information by using a nonvolatile / volatile semiconductor memory element to be stored. Each part of the television ex300 is connected to each other via a synchronous bus.

First, a configuration in which the television ex300 decodes and reproduces data acquired from the outside by the antenna ex204 and the like will be described. The television ex300 receives a user operation from the remote controller ex220 or the like, and demultiplexes the video data and audio data demodulated by the modulation / demodulation unit ex302 by the multiplexing / separation unit ex303 based on the control of the control unit ex310 having a CPU or the like. . Furthermore, the television ex300 decodes the separated audio data by the audio signal processing unit ex304, and the separated video data is decoded by the video signal processing unit ex305 using the decoding method described in the above embodiment. The decoded audio signal and video signal are output to the outside from the output unit ex309. When outputting, these signals may be temporarily stored in the buffers ex318, ex319, etc. so that the audio signal and the video signal are reproduced in synchronization. Further, the television ex300 may read the encoded bitstream encoded from the recording media ex215 and ex216 such as a magnetic / optical disk and an SD card, not from a broadcast or the like. Next, a configuration will be described in which the television ex300 encodes an audio signal and a video signal and transmits them to the outside or writes them to a recording medium or the like. The television ex300 receives a user operation from the remote controller ex220 or the like, and encodes an audio signal with the audio signal processing unit ex304 based on the control of the control unit ex310, and the video signal with the video signal processing unit ex305 in the above embodiment. Encoding is performed using the described encoding method. The encoded audio signal and video signal are multiplexed by the multiplexing / demultiplexing unit ex303 and output to the outside. When multiplexing, these signals may be temporarily stored in the buffers ex320 and ex321 so that the audio signal and the video signal are synchronized. Note that a plurality of buffers ex318 to ex321 may be provided as shown in the figure, or a configuration in which one or more buffers are shared may be used. Further, in addition to the illustrated example, data may be stored in the buffer as a buffer material that prevents system overflow and underflow even between the modulation / demodulation unit ex302 and the multiplexing / demultiplexing unit ex303, for example.

In addition to acquiring audio data and video data from broadcast and recording media, the television ex300 has a configuration for receiving AV input of a microphone and a camera, and even if encoding processing is performed on the data acquired therefrom Good. Here, the television ex300 has been described as a configuration capable of the above-described encoding processing, multiplexing, and external output. However, all of these processing cannot be performed, and the above reception, decoding processing, and external The configuration may be such that only one of the outputs is possible.

When the encoded bitstream is read from or written to the recording medium by the reader / recorder ex218, the decoding process or the encoding process may be performed by either the television ex300 or the reader / recorder ex218. The television ex300 and the reader / recorder ex218 may be shared with each other.

As an example, FIG. 32 shows the configuration of the information reproducing / recording unit ex400 when data is read from or written to the optical disk. The information reproducing / recording unit ex400 includes elements ex401 to ex407 described below. The optical head ex401 irradiates a laser spot on the recording surface of the recording medium ex215 that is an optical disc to write information, and detects information reflected from the recording surface of the recording medium ex215 to read the information. The modulation recording unit ex402 electrically drives a semiconductor laser built in the optical head ex401 and modulates the laser beam according to the recording data. The reproduction demodulator ex403 amplifies a reproduction signal obtained by electrically detecting reflected light from the recording surface by a photodetector built in the optical head ex401, separates and demodulates a signal component recorded on the recording medium ex215, and is necessary. To play back information. The buffer ex404 temporarily holds information to be recorded on the recording medium ex215 and information reproduced from the recording medium ex215. The disk motor ex405 rotates the recording medium ex215. The servo control unit ex406 moves the optical head ex401 to a predetermined information track while controlling the rotational drive of the disk motor ex405, and performs a laser spot tracking process. The system control unit ex407 controls the entire information reproduction / recording unit ex400. In the reading and writing processes described above, the system control unit ex407 uses various types of information held in the buffer ex404, and generates and adds new information as necessary. This is realized by recording / reproducing information through the optical head ex401 while the unit ex403 and the servo control unit ex406 are operated cooperatively. The system control unit ex407 includes, for example, a microprocessor, and executes these processes by executing a read / write program.

In the above, the optical head ex401 has been described as irradiating a laser spot, but it may be configured to perform higher-density recording using near-field light.

FIG. 33 shows a schematic diagram of a recording medium ex215 that is an optical disk. Guide grooves (grooves) are formed in a spiral shape on the recording surface of the recording medium ex215, and address information indicating the absolute position on the disc is recorded in advance on the information track ex230 by changing the shape of the groove. This address information includes information for specifying the position of the recording block ex231 which is a unit for recording data, and the recording and reproducing apparatus specifies the recording block by reproducing the information track ex230 and reading the address information. be able to. Further, the recording medium ex215 includes a data recording area ex233, an inner peripheral area ex232, and an outer peripheral area ex234. The area used for recording user data is the data recording area ex233, and the inner circumference area ex232 and the outer circumference area ex234 arranged on the inner circumference or outer circumference of the data recording area ex233 are used for specific purposes other than recording user data. Used. The information reproducing / recording unit ex400 reads / writes encoded audio data, video data, or encoded data obtained by multiplexing these data, with respect to the data recording area ex233 of the recording medium ex215.

In the above description, an optical disk such as a single-layer DVD or BD has been described as an example. However, the present invention is not limited to these, and an optical disk having a multilayer structure and capable of recording other than the surface may be used. It also has a structure that performs multidimensional recording / reproduction, such as recording information using light of various different wavelengths at the same location on the disc, and recording different layers of information from various angles. It may be an optical disk.

Also, in the digital broadcasting system ex200, the car ex210 having the antenna ex205 can receive data from the satellite ex202 and the like, and the moving image can be reproduced on a display device such as the car navigation ex211 that the car ex210 has. For example, the configuration of the car navigation ex211 may include a configuration in which a GPS receiving unit is added in the configuration illustrated in FIG. 31, and the same may be applied to the computer ex111 and the mobile phone ex114. In addition to the transmission / reception terminal having both an encoder and a decoder, the mobile phone ex114 and the like can be used in three ways: a transmitting terminal having only an encoder and a receiving terminal having only a decoder. The implementation form of can be considered.

As described above, the image encoding method or the image decoding method described in the above embodiment can be used in any of the above-described devices and systems, and by doing so, the effects described in the above embodiment can be obtained. be able to.

Further, the present invention is not limited to the above-described embodiment, and various changes or modifications can be made without departing from the scope of the present invention.

(Embodiment 5)
The image encoding method and apparatus and image decoding method and apparatus described in the above embodiments are typically realized by an LSI that is an integrated circuit. As an example, FIG. 34 shows a configuration of an LSI ex500 that is made into one chip. The LSI ex500 includes elements ex501 to ex509 described below, and each element is connected via a bus ex510. The power supply circuit unit ex505 starts up to an operable state by supplying power to each unit when the power supply is in an on state.

For example, when performing the encoding process, the LSI ex500 inputs an AV signal from the microphone ex117, the camera ex113, and the like by the AV I / Oex 509 based on the control of the control unit ex501 having the CPU ex502, the memory controller ex503, the stream controller ex504, and the like. Accept. The input AV signal is temporarily stored in an external memory ex511 such as SDRAM. Based on the control of the control unit ex501, the accumulated data is appropriately divided into a plurality of times according to the processing amount and the processing speed, and sent to the signal processing unit ex507. The signal processing unit ex507 performs encoding of an audio signal and / or encoding of a video signal. Here, the encoding process of the video signal is the encoding process described in the above embodiment. The signal processing unit ex507 further performs processing such as multiplexing the encoded audio data and the encoded video data according to circumstances, and outputs the result from the stream I / Oex 506 to the outside. The output bit stream is transmitted to the base station ex107 or written to the recording medium ex215. It should be noted that data should be temporarily stored in the buffer ex508 so that the data is synchronized when multiplexed.

Further, for example, when performing decoding processing, the LSI ex500 is obtained by reading from the encoded data obtained via the base station ex107 by the stream I / Oex 506 or the recording medium ex215 based on the control of the control unit ex501. The encoded data is temporarily stored in the memory ex511 or the like. Based on the control of the control unit ex501, the accumulated data is appropriately divided into a plurality of times according to the processing amount and the processing speed and sent to the signal processing unit ex507. The signal processing unit ex507 performs decoding of audio data and / or decoding of video data. Here, the decoding process of the video signal is the decoding process described in the above embodiment. Further, in some cases, each signal may be temporarily stored in the buffer ex508 or the like so that the decoded audio signal and the decoded video signal can be reproduced in synchronization. The decoded output signal is output from each output unit such as the mobile phone ex114, the game machine ex115, and the television ex300 through the memory ex511 or the like as appropriate.

In the above description, the memory ex511 has been described as an external configuration of the LSI ex500. However, a configuration included in the LSI ex500 may be used. The buffer ex508 is not limited to one, and a plurality of buffers may be provided. The LSI ex500 may be made into one chip or a plurality of chips.

In addition, although it was set as LSI here, it may be called IC, system LSI, super LSI, and ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology that replaces LSI emerges as a result of advances in semiconductor technology or other derived technology, it is naturally also possible to integrate functional blocks using this technology. Biotechnology can be applied.

The image encoding method, the image encoding device, the image decoding method, and the image decoding device according to the present invention have been described based on the embodiments. However, the present invention is not limited to these embodiments. Absent. Unless it deviates from the meaning of the present invention, various forms conceived by those skilled in the art are applied to the embodiment, and other forms constructed by combining components and steps in different embodiments are also included in the present invention. It is included in the range.

The image encoding method and the image decoding method according to the present invention can be used for, for example, a television, a digital video recorder, a car navigation, a mobile phone, a digital camera, a digital video camera, or the like.

400, 500 calculation unit 402, 502, 2101 writing unit 404 distortion calculation unit 406, 506 conversion block size selection unit 408, 508, 1202, 1402 subtraction unit 410, 510, 1204, 1404, 2103, 2204, 2404, 2601 conversion Unit 412, 512, 1206, 1406, 2104, 2205, 2405, 2602 quantization unit 414, 514, 1208, 1302, 1408, 1502, 2304, 2504, 2701 Inverse quantization unit 416, 516, 1212, 1304, 1412, 1504, 2305, 2505, 2702 Inverse transformation unit 418, 518, 1214, 1310, 1414 Memory unit 420, 520, 1210, 1308, 1410, 1508 Sample prediction unit 422, 522, 1216, 141 Adder 450, 550, 1250, 1450, 2100, 2200, 2400, 2600 Image encoding device 504 Edge detector 1200, 1300 Quantization matrix correction unit 1306, 1506 Sample reconstruction unit 1350, 1550, 2300, 2500, 2700 Image Decoding device 1400, 1500 Quantized offset matrix selection unit 1418, 2401 First writing unit 1420, 2403 Second writing unit 1510 First memory unit 1512, 2501 First analysis unit 1514, 2502 Second analysis unit 1516 Second memory Unit 2102 size determination unit 2201, 2301 quantization parameter determination unit 2202, 2302 matrix determination unit 2203, 2303 matrix correction unit 2402, 2503 selection unit D401, D403, D405 D407, D501, D503, D505, D507 Parameter set D408 Cost value D409, D509, D1207, D1407 Image sample D410, D510 Conversion block size D411, D511, D1209, D1311, D1409, D1511 Residual block D413, D513, D11 Coefficient block D415, D515, D1215, D1415 Coding sample D417, D517, D1219, D1309, D1419, D1509 Dequantized coefficient D419, D519, D1221, D1421 Reconstructed residual block D421, D425, D521, D525, D1223, D1225 D1315, D1317, D1423, D1425, D1515, D1517 Reconstructed sample D 423, D523, D1213, D1313, D1413, D1513 Prediction sample D508 Edge information D1201, D1301 Quantization scaling matrix D1203, D1303, D1401, D1403, D1417, D1427, D1501, D1503, D1519 Quantization offset matrix D1205, D1305 Quantization parameter D1217, D1319 Quantization matrix D1307, D1507 Encoding block D1405, D1429, D1505, D1602 Matrix selection flag D1600 Picture ex100 Content supply system ex101 Internet ex102 Internet service provider ex103 Streaming server ex104 Telephone network ex106, ex107 ex108, ex109, ex110 base station ex111 computer ex112 PDA
ex113, ex116 Camera ex114 Digital mobile phone with camera (cell phone)
ex115 Game console ex117 Microphone ex200 Digital broadcasting system ex201 Broadcast station ex202 Broadcast satellite (satellite)
ex203 Cable ex204, ex205, ex601 Antenna ex210 Car ex211 Car navigation (car navigation system)
ex212 Playback device ex213, ex219 Monitor ex214, ex215, ex216, ex607 Recording media ex217 Set-top box (STB)
ex218 reader / recorder ex220 remote controller ex230 information track ex231 recording block ex232 inner circumference area ex233 data recording area ex234 outer circumference area ex300 television ex301 tuner ex302 modulation / demodulation section ex303 multiplexing / separation section ex304 audio signal processing section ex305 video signal processing section ex306, ex507 Signal processing unit ex307 Speaker ex308, ex602 Display unit ex309 Output unit ex310, ex501 Control unit ex311, ex505, ex710 Power supply circuit unit ex312 Operation input unit ex313 Bridge ex314, ex606 Slot unit ex315 Driver ex316, Ex317 Interface unit 3 , Ex321, ex404, ex508 Buffer ex400 Information reproducing / recording unit ex401 optical head ex402 modulation recording unit ex403 reproducing demodulating portion ex405 Disk motor ex406 Servo control unit ex407 System control unit EX500 LSI
ex502 CPU
ex503 Memory controller ex504 Stream controller ex506 Stream I / O
ex509 AV I / O
ex510 bus ex511 memory ex603 camera unit ex604 operation key ex605 audio input unit ex608 audio output unit ex701 transmission / reception circuit unit ex702 LCD control unit ex703 camera interface unit (camera I / F unit)
ex704 operation input control unit ex705 audio processing unit ex706 modulation / demodulation circuit unit ex707 recording / playback unit ex708 demultiplexing unit ex709 image decoding unit ex711 main control unit ex712 image encoding unit ex713 synchronization bus

Claims

An image encoding method for encoding an image for each block,
A conversion step of converting a plurality of pixel values included in the block into a plurality of frequency coefficients;
A quantization step of quantizing the plurality of frequency coefficients using a parameter set including at least one of a quantization scaling matrix determined for each block and a quantization offset matrix determined for each block An image encoding method including:
The image encoding method further includes a plurality of quantization scaling matrices corresponding to a plurality of block sizes, and a writing step of writing a plurality of quantization offset values corresponding to the plurality of block sizes in a header,
In the writing step, a first quantization offset value corresponding to a first block size among the plurality of block sizes is written as one of the plurality of quantization offset values,
In the writing step, a first quantization scaling matrix corresponding to the first block size is written as one of the plurality of quantization scaling matrices,
In the writing step, a second quantization offset value corresponding to a second block size that is smaller than the first block size among the plurality of block sizes, and is larger than the first quantization offset value. Writing a second quantization offset value as one of the plurality of quantization offset values;
In the writing step, the second quantization scaling matrix corresponding to the second block size, the second quantization scaling matrix being smaller than the first quantization scaling matrix, the plurality of quantization scaling matrices As one of the writing,
In the conversion step, the plurality of pixel values included in the block formed with a block size of any of the plurality of block sizes are converted into the plurality of frequency coefficients,
In the quantization step, the quantization scaling matrix corresponding to the block size of the block among the plurality of quantization scaling matrices and the block size of the block among the plurality of quantization offset values are set. The image coding method according to claim 1, wherein the plurality of frequency coefficients are quantized using the parameter set including a corresponding quantization offset value.
The image encoding method further detects the distortion cost calculated by calculating a distortion cost indicating a magnitude of distortion caused by the quantization of the plurality of frequency coefficients, or an edge included in the image. Determining a block size of the block as a function of the detected edge;
The image encoding method according to claim 2, wherein in the converting step, the plurality of pixel values included in the block formed with the determined block size are converted into the plurality of frequency coefficients.
The image encoding method further includes:
A quantization parameter determining step for determining a quantization parameter corresponding to the block;
A matrix determining step for determining the quantization scaling matrix corresponding to the block;
A slope indicating a ratio of a change in a quantization scaling value to a change in a frequency in the determined quantization scaling matrix by modifying the determined quantization scaling matrix depending on the determined quantization parameter. A matrix correction step for correcting
The image code according to claim 1, wherein the quantization step quantizes the plurality of frequency coefficients using the modified quantization scaling matrix and the parameter set including the determined quantization parameter. Method.
In the matrix correction step, when the determined quantization parameter is a second quantization parameter larger than the first quantization parameter, the determined quantization parameter is more than the first quantization parameter. The image coding method according to claim 4, wherein the quantization scaling matrix is modified so that the inclination becomes steep.
The image encoding method further includes:
A quantization parameter determining step for determining a quantization parameter corresponding to the block;
A matrix determining step for determining the quantization offset matrix corresponding to the block;
The slope indicating the ratio of the change in the quantization offset value to the change in the frequency in the determined quantization offset matrix by modifying the determined quantization offset matrix depending on the determined quantization parameter. A matrix correction step for correcting
The image code according to claim 1, wherein in the quantization step, the plurality of frequency coefficients are quantized using the modified quantization offset matrix and the parameter set including the determined quantization parameter. Method.
In the matrix correction step, when the determined quantization parameter is a second quantization parameter larger than the first quantization parameter, the determined quantization parameter is more than the first quantization parameter. The image encoding method according to claim 6, wherein the quantization offset matrix is corrected so that the inclination becomes steep.
The image encoding method further includes:
A first writing step of writing a first quantized offset matrix into the header;
The quantization offset matrix used for quantization of the plurality of frequency coefficients is selected from the first quantization offset matrix and a predetermined second quantization offset matrix different from the first quantization offset matrix. A selection step to
A second writing step of writing a flag indicating a predetermined value in the block header when the second quantization offset matrix is selected;
The image coding method according to claim 1, wherein in the quantization step, the plurality of frequency coefficients are quantized using the parameter set including the selected quantization offset matrix.
An image decoding method for decoding an image block by block,
Using a parameter set including at least one of a quantization scaling matrix determined for each block and a quantization offset matrix determined for each block, a plurality of frequency coefficients included in the block are inversely quantized. An inverse quantization step to
An inverse transforming step of transforming the plurality of frequency coefficients that have been inversely quantized into a plurality of pixel values.
The image decoding method further includes:
A quantization parameter determining step for determining a quantization parameter corresponding to the block;
A matrix determining step for determining the quantization scaling matrix corresponding to the block;
A slope indicating a ratio of a change in a quantization scaling value to a change in a frequency in the determined quantization scaling matrix by modifying the determined quantization scaling matrix depending on the determined quantization parameter. A matrix correction step for correcting
10. The dequantization step includes dequantizing the plurality of frequency coefficients using the modified quantization scaling matrix and the parameter set including the determined quantization parameter. Image decoding method.
In the matrix correction step, when the determined quantization parameter is a second quantization parameter larger than the first quantization parameter, the determined quantization parameter is more than the first quantization parameter. The image decoding method according to claim 10, wherein the quantization scaling matrix is corrected so that the inclination becomes steep.
The image decoding method further includes:
A quantization parameter determining step for determining a quantization parameter corresponding to the block;
A matrix determining step for determining the quantization offset matrix corresponding to the block;
The slope indicating the ratio of the change in the quantization offset value to the change in the frequency in the determined quantization offset matrix by modifying the determined quantization offset matrix depending on the determined quantization parameter. A matrix correction step for correcting
10. The dequantizing step includes dequantizing the plurality of frequency coefficients using the modified quantization offset matrix and the parameter set including the determined quantization parameter. Image decoding method.
In the matrix correction step, when the determined quantization parameter is a second quantization parameter larger than the first quantization parameter, the determined quantization parameter is more than the first quantization parameter. The image decoding method according to claim 12, wherein the quantization offset matrix is corrected so that the inclination becomes steep.
The image decoding method further includes:
A first analysis step of obtaining a first quantization offset matrix from the header by analyzing the header;
A second analysis step of obtaining a flag from the block header by analyzing the block header;
When the acquired flag indicates a predetermined value, a predetermined second quantization offset matrix different from the first quantization offset matrix is determined for each block. Selecting the first quantization offset matrix as the quantization offset matrix determined for each block when the acquired flag does not indicate the predetermined value. ,
The image decoding method according to claim 9, wherein, in the inverse quantization step, the plurality of frequency coefficients are inversely quantized using the parameter set including the selected quantization offset matrix.
An image encoding device for encoding an image for each block,
A conversion unit that converts a plurality of pixel values included in the block into a plurality of frequency coefficients;
A quantization unit that quantizes the plurality of frequency coefficients using a parameter set including at least one of a quantization scaling matrix determined for each block and a quantization offset matrix determined for each block An image encoding device comprising:
An image decoding device for decoding an image for each block,
Using a parameter set including at least one of a quantization scaling matrix determined for each block and a quantization offset matrix determined for each block, a plurality of frequency coefficients included in the block are inversely quantized. An inverse quantization unit that
An image decoding apparatus comprising: an inverse transform unit configured to transform the plurality of frequency coefficients subjected to inverse quantization into a plurality of pixel values.
A program for causing a computer to execute the steps included in the image encoding method according to claim 1.
A program for causing a computer to execute the steps included in the image decoding method according to claim 9.
An integrated circuit that encodes an image block by block,
A conversion unit that converts a plurality of pixel values included in the block into a plurality of frequency coefficients;
A quantization unit that quantizes the plurality of frequency coefficients using a parameter set including at least one of a quantization scaling matrix determined for each block and a quantization offset matrix determined for each block And an integrated circuit.
An integrated circuit that decodes an image block by block,
Using a parameter set including at least one of a quantization scaling matrix determined for each block and a quantization offset matrix determined for each block, a plurality of frequency coefficients included in the block are inversely quantized. An inverse quantization unit that
An integrated circuit, comprising: an inverse conversion unit configured to convert the plurality of inversely quantized frequency coefficients into a plurality of pixel values.