JP2004343279A - Image processing apparatus and method, information processing apparatus, recording medium, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent image quality deterioration in the case that a quantized value cannot be reused. <P>SOLUTION: A flowchart for explaining a quantization matrix determination processing 1 includes: a step S1 of discriminating whether or not past encoding information is reused for encoding; a step S2 of reading an intra quantization matrix used for ordinary encoding from a memory when the past encoding information is not reused for the encoding; a step S3 of discriminating whether or not the quantized value is reusable when the past encoding information is reused for the encoding; a step S4 of supplying the intra quantization matrix in the past encoding to a quantization section when the quantized value is reusable; and a step S5 of reading the intra quantization matrix comprising a sufficiently smaller (e.g., 32 or below) high frequency component such as a value twice the DC component from the memory when the quantized value is not reusable. The image processing apparatus or the like is applicable to SDTI-ASI converters or Long GOP encoders. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing device and an image processing method, an information processing device, a recording medium, and a program, and more particularly to re-encoding corresponding data using information on encoding performed in the past. The present invention relates to an image processing device and an image processing method, an information processing device, a recording medium, and a program that are suitable for use when possible.
[0002]
[Prior art]
For example, in a system for transmitting a moving image signal to a remote place such as a video conference system and a video telephone system, in order to efficiently use a transmission path, line correlation or inter-frame correlation of a video signal is used. The image signal is compression-encoded.
[0003]
When an image signal is compression-encoded, encoding is performed so that a generated bit stream has a predetermined bit rate. However, in actual operation, it may be necessary to convert the bit rate of the bit stream depending on the transmission path.
[0004]
Further, for example, when a transmitted image signal is edited in a broadcasting station, the editing is performed in units of seconds, so that the image information of a frame is preferably independent of the image information of another frame. Therefore, a long GOP having a large number of frames constituting a GOP (Group of Pictures), which is a set of frames having correlated information, so that image quality does not deteriorate even when transferred at a low bit rate (for example, 3 to 9 Mbps). And a Short GOP, which is transferred at a high bit rate (18 to 50 Mbps) and has a small number of frames constituting the GOP, needs to be mutually converted.
[0005]
For example, a system capable of editing a frame after encoding uncompressed data into MPEG Long GOP stream data will be described with reference to FIG.
[0006]
The SDI (Serial Digital Interface) -ASI (Asynchronous Serial Interface) converter 1 encodes the supplied SDI input image into an MPEG Long GOP (ASI stream), and encodes the encoded MPEG Long GOP. Output stream data. The SDI is an uncompressed digital video and audio transmission system based on the point-to-point transmission, and is defined in ANSI (American National Standards Institute) / SMPTE (Society of Motion picture rule in the 9th edition). ing.
[0007]
The ASI-SDTI CP (Serial Data Transport Content Contents Package) converter 2 temporarily decodes the supplied MPEG Long GOP stream data in the decoding unit 21, and then in the encoding unit 22, all the intra frames (All Intra ), And outputs the coded stream data (SDTI CP stream) of all the intra frames to the frame editing device 3 of the SDTI CP interface. SDTI CP is a global standard for a transmission method for transmitting (synchronous transfer) MPEG data in real time, which has been standardized as SMPTE 326M by the promotion of the Pro-MPEG Forum.
[0008]
The stream data edited by the frame editing device 3 is supplied to the SDTI CP-ASI conversion device 4. The SDTI CP-ASI conversion device 4 once decodes the supplied stream data of all the intra frames in the decoding unit 31, and then encodes the encoded data into the Long GOP of MPEG in the encoding unit 32, and performs the encoding. It outputs stream data (ASI stream) of MPEG Long GOP.
[0009]
A system that can encode an input image at a high bit rate into an MPEG Long GOP, decode it, and re-encode it into a low bit rate MPEG Long GOP will be described with reference to FIG.
[0010]
After the supplied SDI input image is once decoded by the decoding unit 61, the Long GOP encoding device 51 encodes the encoded SDI input image into a high bit rate MPEG Long GOP and encodes the encoded SDI image. It outputs MPEG Long GOP stream (ASI stream) data. The Long GOP encoding device 52 once decodes the supplied high bit rate MPEG Long GOP by the decoding unit 71, and then encodes the low bit rate MPEG Long GOP by the encoding unit 72. And outputs encoded low bit rate MPEG Long GOP stream (ASI stream) data.
[0011]
As described above, when the encoding and decoding of the image information are repeated, if the encoding parameter used for each encoding changes, the image information deteriorates. In order to prevent the deterioration of the image information, there is a technique capable of suppressing the deterioration of the image due to the re-encoding by using the encoding history information inserted in the user data area of the picture layer of the bit stream ( For example, see Patent Document 1).
[0012]
[Patent Document 1]
JP 2000-059788 A
[0013]
For example, a case where encoding history information is used in a system capable of performing frame editing after encoding uncompressed data into MPEG Long GOP stream data will be described with reference to FIG. The parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0014]
That is, the ASI-SDTI CP converter 101 receives the supply of the MPEG Long GOP (ASI stream) generated by being encoded by the SDI-ASI converter 1 similar to FIG.
[0015]
Since the Long GOP of MPEG is composed of three types of pictures (I picture, P picture, and B picture) having different encoding characteristics, the video data obtained by decoding the picture and the I picture depend on the frame. Some have the features of pictures, P pictures, and B pictures. Therefore, when re-encoding this video data using the Long GOP of MPEG, if video data having the characteristics of I picture, P picture, or B picture is encoded with different picture types, Image degradation may occur. For example, before decoding, if video data that was a B-picture, which tends to have more distortion than an I-picture and a P-picture, is encoded as an I-picture, surrounding pictures are predicted using the I-picture with a large distortion as a reference picture. Since the image is coded, the image quality deteriorates.
[0016]
In order not to cause the image quality deterioration due to such re-encoding, the ASI-SDTICP conversion apparatus 101 once decodes the supplied MPEG Long GOP stream data in the decoding When encoding to be an intra frame, the encoding performed in the past, that is, the parameters such as the picture type and quantization value of the encoding by the SDI-ASI conversion device 1 are all performed in the SDTI-CP stream of the intra frame. The information is added to the above as history information (History data) of SMPTE 328M and supplied to the frame editing device 3.
[0017]
The stream data edited by the frame editing device 3 is supplied to the SDTI CP-ASI conversion device 102. In the SDTI CP-ASI conversion apparatus 102, the decoding unit 121 decodes the supplied stream data of all intra frames with history information. The encoding unit 122 re-encodes it into a Long GOP using necessary parameters such as a picture type and a quantization value included in the decoded history information, and outputs the Long GOP.
[0018]
Further, as described with reference to FIG. 2, in a system capable of encoding an input image at a high bit rate into an MPEG Long GOP, decoding the image, and re-encoding the input image into a low bit rate MPEG Long GOP, A case where image degradation for re-encoding is prevented from occurring will be described with reference to FIG. Parts corresponding to those in FIG. 2 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0019]
That is, the Long GOP encoding device 131, which receives the supply of the MPEG Long GOP stream (ASI stream) data encoded by the Long GOP encoding device 51, decodes the high bit rate MPEG Long GOP by the decoding unit 141. Then, necessary encoding parameters are acquired, and the decoded video data and the acquired encoding parameters are supplied to the encoding unit 142. The encoding unit 142 encodes the video data into a low bit rate MPEG Long GOP using the supplied encoding parameters, and encodes the encoded low bit rate MPEG Long GOP stream ( (ASI stream) data.
[0020]
[Problems to be solved by the invention]
As described above, coding is performed by reusing past coding information (picture type, motion vector, quantization value, etc. of coding performed in the past) using history information or coding parameters. By doing so, it is possible to prevent image quality deterioration. However, when the bit rate is reduced by re-encoding as in the system described with reference to FIG. 4, if the quantized value is used as it is, the bit rate cannot be reduced. Can not do it. In addition, in the system described with reference to FIG. 3, for example, depending on the state of the VBV buffer at the time of encoding a stream including an edit point, it may not be possible to perform encoding by reusing the quantization value.
[0021]
As described above, when the past information is reused and encoded using the history information or the encoding parameter, the quantization value of the history information or the information included in the encoding parameter is used. If cannot be reused, the quantization value is determined by rate control such as TM5 used in normal encoding. That is, the quantized value used for encoding differs from the quantized value of past encoding.
[0022]
Furthermore, when an encoding device or transcoder in which encoding has been performed in the past is different from an encoding device or transcoder that performs re-encoding and the rate control method or the like differs depending on the device, the past encoding and the next encoding are performed next. In the coding to be performed, the quantization values are likely to be different.
[0023]
If the quantized value used in the re-encoding is different from the quantized value in the past encoding, the difference may cause image quality degradation. For example, when there is a difference between the quantization value in the past encoding and the quantization value which is about twice as large, the image quality is remarkably degraded, and the quantization value in the past encoding is reduced by 2 times. When the difference of the quantization value is twice or more, the image quality is further remarkably deteriorated.
[0024]
The following can be considered as the cause, for example.
[0025]
When video data to be encoded contains many high-frequency components such as noise and fine texture, DCT coefficients which do not become 0 even after quantization are widely distributed to higher orders. For example, consider a case where a result of quantizing a certain higher-order coefficient in an intra macroblock is 1. In re-encoding, if this part is quantized with a double quantization value, the result will be 0.5 and will be 1 again due to rounding. Furthermore, since it is inversely quantized at the time of decoding and multiplied by twice the quantized value, the coefficient value is twice the coefficient value at the time of past encoding. Therefore, when inverse DCT is performed, high frequency components such as noise and fine texture of video data are emphasized as compared with input video data at the time of past encoding.
[0026]
Further, when the same part is quantized using a quantization value that is more than twice in the re-encoding, the coefficient is rounded to 0, and the resolution is reduced. In such a case, in an encoding apparatus that performs the quantization calculation by truncation, the quantization value used in the re-encoding becomes slightly larger than the past quantization value, and the quantization result becomes 0. Therefore, all data that is 1 in the past becomes 0, the resolution is reduced, and the image is degraded.
[0027]
In particular, when a portion that was an I-picture in the past encoding is re-encoded as an I-picture again, image quality degradation such as enhancement of high-frequency components and reduced resolution is likely to occur. Therefore, in the re-encoded video data, the high frequency component is emphasized only in the I picture portion or the resolution is reduced. Therefore, only the portion corresponding to the I picture in the reproduced video data is emphasized. As a result, flicker occurs.
[0028]
When the bit rate is reduced, the above-described image quality degradation is likely to occur because the quantization value is likely to increase. Even if the bit rate remains the same, if the input video data at the time of re-encoding is different from the input video data at the time of past encoding, the bit rate of the I picture, P picture, and B picture A difference occurs in the allocation of generation amount. Even in such a case, since the quantization value may be different from that at the time of the past encoding, image quality degradation may occur depending on the magnitude of the difference from the past quantization value. I will.
[0029]
The present invention has been made in view of such a situation, and in the case of encoding by reusing parameters in past encoding, when quantization values cannot be reused, image quality degradation occurs. It is to be able to prevent that.
[0030]
[Means for Solving the Problems]
A first image processing apparatus according to the present invention includes: an obtaining unit that obtains information related to encoding performed on image data in the past; an orthogonal transform unit that performs orthogonal transform on image data; Storage means for storing a first quantization matrix composed of the following values: determination means for determining a quantization value and a quantization matrix used for quantization; and a quantization value and a quantization value determined by the determination means. Using a quantization matrix, performing quantization, and determining the information obtained by the obtaining unit when the quantization value included in the information obtained by the obtaining unit is reusable. Is determined to be used for quantization, and if the quantization value included in the information is not reusable, the first quantization matrix stored in the storage unit is determined. And determining the use Coca.
[0031]
The first quantization matrix may be configured such that the high-frequency component has a value equal to or less than twice the DC component.
[0032]
In the first quantization matrix, the high-frequency component may be configured with a value of 32 or less.
[0033]
An encoding unit for encoding the quantized coefficient data quantized by the quantization unit may be further provided.
[0034]
The first quantization matrix stored in the storage unit may include a quantization matrix used for quantizing an intra macroblock.
[0035]
The first quantization matrix stored in the storage means includes a third quantization matrix used for quantization of intra macroblocks and a fourth quantization matrix used for quantization of non-intra macroblocks. be able to.
[0036]
The storage means may further store a third quantization matrix used when the information obtained by the obtaining means is not reused in the quantization, and the determining means may store the third quantization matrix obtained by the obtaining means. It is possible to further determine whether or not the obtained information is reused, when the information is reused and the quantization value included in the information obtained by the obtaining unit is reusable , The determining means can determine to use the second quantization matrix included in the information acquired by the acquiring means for quantization, and the information is reused and included in the information. If the quantized value is not reusable, the determining means may be caused to determine that the first quantization matrix stored in the storage means is used for quantization, and the information is re-used. If not use, the determining means, the third quantization matrix stored in the storage means may be adapted to determine that used in quantization.
[0037]
The AC components of the first quantization matrix stored by the storage unit can all have the same value.
[0038]
A first image processing method according to the present invention includes: a determination step of determining whether a quantization value included in information regarding encoding performed in the past on image data is used for quantization; When it is determined that the quantization value is not used for the quantization by the processing of the above, the first quantization matrix in which the high frequency component is configured with a value of less than 255 is used as the quantization matrix used for the quantization. When it is determined that the quantization value is used for the quantization by the processing of the first selection step of selecting and the determination step, the second quantization matrix included in the information is used as the quantization matrix used for the quantization. And a second selecting step of selecting.
[0039]
The program recorded on the first recording medium of the present invention determines whether or not a quantization value included in information on encoding performed in the past on image data is used for quantization. When it is determined that the quantization value is not used for the quantization by the processing of the step and the determination step, the first quantization matrix including the high-frequency component having a value less than 255 is converted to the quantization. When it is determined that the quantization value is used for quantization by the processing of the first selection step of selecting a quantization matrix to be used and the determination step, the second quantization matrix included in the information is used for quantization. And a second selection step of selecting a quantization matrix to be used.
[0040]
A first program according to the present invention includes a determining step of determining whether a quantization value included in information on encoding performed in the past on image data is used for quantization, and a processing of the determining step. , When the quantization value is determined not to be used for quantization, the first quantization matrix in which the high-frequency component is configured with a value less than 255 is selected as the quantization matrix used for quantization. When it is determined that the quantization value is used for the quantization by the processing of the first selection step and the determination step, the second quantization matrix included in the information is selected as the quantization matrix used for the quantization. And a second selecting step.
[0041]
According to the first image processing apparatus, the image processing method, and the program of the present invention, information relating to encoding performed on image data in the past is acquired, and a quantization value included in the information is determined by the quantization. If the quantization value included in the information is determined not to be used for the quantization, it is determined whether the high-frequency component is less than 255. If it is determined that the matrix is used for quantization and the quantization value included in the information is used for quantization, the second quantization matrix included in the information is used for quantization.
[0042]
A second image processing apparatus according to the present invention includes: an obtaining unit that obtains information regarding encoding performed in the past on image data; an orthogonal transform unit that performs orthogonal transform on the image data; Storage means for storing a first quantization matrix used when acquired information is not reused, and a second quantization matrix in which each component has a value equal to or smaller than the first quantization matrix; Determining means for determining a quantization value and a quantization matrix used for, and a quantization means for performing quantization using the quantization value and the quantization matrix determined by the determination means, When the information is reused and the quantization value included in the information acquired by the acquisition unit is reusable, the third quantization included in the information acquired by the acquisition unit If it is determined that the tricks are to be used for quantization and the information is reused and the quantization value included in the information is not reusable, the second quantization matrix stored in the storage means is quantized. If the information is not reused, it is determined that the first quantization matrix stored in the storage unit is used for quantization.
[0043]
A second image processing method according to the present invention includes a first determining step of determining whether to reuse information on encoding performed in the past on image data, and a process of the first determining step. If it is determined that the past coding information is not reused, a first selection step of selecting a predetermined first quantization matrix as a quantization matrix used for quantization, and a first determination step When it is determined by the processing that information on past encoding is to be reused, a second determination step of determining whether or not a quantization value included in the information is used for quantization; When it is determined by the processing of the determination step that the quantization value is not used for the quantization, the second quantization matrix having each component having a value equal to or less than the first quantization matrix is used for the quantization used for the quantization. Matrix and When it is determined that the quantized value is used for quantization by the processing of the second selection step of selecting by using and the second determination step, the third quantization matrix included in the information is used for quantization. And a third selecting step of selecting as a quantization matrix.
[0044]
The program recorded on the second recording medium according to the present invention includes a first determining step of determining whether or not information relating to encoding performed in the past on image data is to be reused; When it is determined by the processing of the determining step that the information of the past encoding is not reused, a first selecting step of selecting a predetermined first quantization matrix as a quantization matrix used for quantization; When it is determined by the processing of the first determining step that information on past encoding is reused, a second determining step of determining whether a quantization value included in the information is used for quantization. And when the second determination step determines that the quantized value is not used for quantization, the second quantized matrix having each component having a value equal to or less than the first quantized matrix is quantized. For conversion When it is determined that the quantization value is used for the quantization by the processing of the second selection step of selecting the quantization matrix to be used as the quantization matrix and the second determination step, the third quantization matrix included in the information is determined by: And a third selection step of selecting a quantization matrix used for quantization.
[0045]
According to a second program of the present invention, a first determining step of determining whether or not information relating to encoding performed in the past on image data in the past is to be reused, and a process of the first determining step include: Is determined not to be reused, the first selection step of selecting a predetermined first quantization matrix as a quantization matrix used for quantization and the processing of the first determination step A second determining step of determining whether or not the quantization value included in the information is used for quantization when it is determined that information on past encoding is reused; and a second determining step. When it is determined that the quantization value is not used for the quantization by the processing of the above, the second quantization matrix in which each component has a value equal to or less than the first quantization matrix is set as the quantization matrix used for the quantization. When it is determined that the quantization value is used for the quantization by the processing of the second selection step of selecting and the second determination step, the third quantization matrix included in the information is used for the quantization used for the quantization. And a third selecting step of selecting as a conversion matrix.
[0046]
According to the second image processing apparatus, the image processing method, and the program of the present invention, information on encoding performed on image data in the past is obtained, and whether or not the image data is reused is determined. Is determined not to be reused, a predetermined first quantization matrix is selected as a quantization matrix used for quantization, and it is determined that information related to past encoding is reused. In this case, it is determined whether or not the quantization value included in the information is used for quantization. If it is determined that the quantization value is not used for quantization, each component is equal to or smaller than the first quantization matrix. Is selected as the quantization matrix used for quantization, and when it is determined that the quantization value is used for quantization, the third quantization matrix included in the information is It is selected as the quantization matrix used in quantization.
[0047]
A first information processing apparatus according to the present invention includes decoding means for completely or incompletely decoding supplied image data, and baseband image data completely decoded by the decoding means, or unreadable by decoding means. Encoding means for completely encoding the image data that has been completely decoded and generated up to the intermediate stage, up to the intermediate stage or completely, Acquisition means for acquiring information on the performed encoding, orthogonal transformation means for orthogonally transforming the image data, and storage means for storing a first quantization matrix in which the high-frequency component is constituted by a value less than 255 Deciding means for deciding a quantization value and a quantization matrix used for quantization, and quantization for performing quantization using the quantization value and the quantization matrix decided by the deciding means. And determining the second quantization matrix included in the information obtained by the obtaining unit when the quantization value included in the information obtained by the obtaining unit is reusable. If it is determined that the quantization value included in the information is not reusable, it is determined that the first quantization matrix stored in the storage unit is used for quantization.
[0048]
In the first information processing apparatus of the present invention, the supplied image data is completely or incompletely decoded, and the completely decoded baseband image data or the image data encoded to an intermediate stage is , Up to an intermediate stage, or complete encoding, in the encoding, information about the encoding performed in the past on the image data is obtained, the image data is orthogonally transformed, and the high frequency component is less than 255 A first quantization matrix composed of values is stored, a quantization value and a quantization matrix used for quantization are determined, and the determined quantization value and quantization matrix are used to perform quantization. Executed, and in the determination of the quantization value and the quantization matrix, if the quantization value included in the obtained information is reusable, the second value included in the obtained information is used. Coca matrix to be determined to be used in quantization, the quantization value contained in the information may not be reusable, the first quantization matrix stored be used in quantization is determined.
[0049]
The second information processing apparatus of the present invention decodes the supplied image data completely or incompletely, and decodes the image data completely or incompletely decoded by the decoding means. Encoding means for encoding in a method corresponding to the state of decoding by the means, wherein the encoding means acquires information on encoding performed in the past on the image data, and orthogonalizes the image data. Orthogonal transformation means for transforming, a first quantization matrix used when information acquired by the acquisition means is not reused in quantization, and a second quantization matrix in which each component has a value equal to or less than the first quantization matrix. Storage means for storing the second quantization matrix, determination means for determining a quantization value and a quantization matrix used for quantization, and quantization value and quantization determined by the determination means. Using the tricks, comprising quantization means for performing quantization, the determination means, if the information is reused, and if the quantization value included in the information acquired by the acquisition means can be reused, It decides to use the third quantization matrix included in the information obtained by the obtaining means for quantization, and stores the information if the information is reused and the quantization value included in the information is not reusable. A decision is made to use the second quantization matrix stored in the means for quantization and, if the information is not reused, a decision is made to use the first quantization matrix stored in the storage means for quantization. It is characterized by doing.
[0050]
In the second information processing apparatus of the present invention, the supplied image data is completely or incompletely decoded, and the image data is encoded by a method corresponding to the decoding state. Information relating to encoding performed in the past is obtained, image data is orthogonally transformed, and in quantization, a first quantization matrix used when the obtained information is not reused, and each component is a first quantization matrix. Is stored, a quantization value and a quantization matrix used for quantization are determined, and using the determined quantization value and the quantization matrix, If the quantization is performed, the information is reused, and the quantization value included in the information acquired by the acquisition unit is reusable, the third information included in the acquired information is used. If it is determined that the quantization matrix is to be used for quantization, the information is reused, and the quantization value included in the information is not reusable, the stored second quantization matrix is used for quantization. If it is decided to use it and the information is not reused, it is decided to use the stored first quantization matrix for quantization.
[0051]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. In order to clarify the correspondence between each means of the invention described in the claims and the following embodiments, parentheses after each means or step are described. The following describes the features of the present invention by adding corresponding embodiments (however, examples). However, of course, this description does not mean that the invention is limited to the description of each means or step.
[0052]
The image processing apparatus according to claim 1 (for example, the encoding unit 161 in FIG. 5, the encoding unit 211 in FIG. 9, or the encoding apparatus 252 in FIG. 15) performed image data in the past. An acquisition unit (for example, the history extraction unit 171 in FIG. 6 or the parameter input unit 221 in FIG. 10) for acquiring information (for example, history information or a parameter) related to encoding, and an orthogonal transform for orthogonally transforming image data Means (for example, the DCT unit 175 in FIG. 6 or FIG. 10) and a first quantization matrix (for example, the quantization matrix in FIG. 8 or FIG. 13) in which the high-frequency component is constituted by a value less than 255 Storage means for storing (for example, the memory 185 in FIG. 6 or FIG. 10) and determination means for determining the quantization value and the quantization matrix used for quantization (for example, FIG. 6 or FIG. 0 (a rate setting unit 177) and a quantization unit (for example, the quantization unit 176 in FIG. 6 or FIG. 10) that performs quantization using the quantization value and the quantization matrix determined by the determination unit. And the determining unit uses the second quantization matrix included in the information obtained by the obtaining unit for quantization when the quantization value included in the information obtained by the obtaining unit is reusable. If the quantization value included in the information is not reusable, it is determined that the first quantization matrix stored in the storage unit is used for quantization.
[0053]
The image processing apparatus according to claim 4, further comprising an encoding unit (for example, the VLC unit 178 in FIG. 6 or FIG. 10) for encoding the quantized coefficient data quantized by the quantization unit. Features.
[0054]
The image processing apparatus according to claim 7, wherein the storage unit is configured to store the third quantization matrix (for example, the quantization matrix of FIG. 7 or FIG. 12) used when the information acquired by the acquisition unit is not reused in the quantization. (Determination matrix), and the determining unit further determines whether the information acquired by the acquiring unit is reused, and the information is reused and included in the information acquired by the acquiring unit. When the quantized value is reusable, the deciding unit decides to use the second quantization matrix included in the information acquired by the acquiring unit for quantization, and the information is reused, and Is not reusable, the decision means decides to use the first quantization matrix stored in the storage means for quantization, and if the information is not reused, the decision means , The third quantization matrix stored in the storage means and determines that used in quantization.
[0055]
An image processing method according to claim 9, a program recorded on a recording medium according to claim 10, and a program according to claim 11, which are information relating to encoding performed on image data in the past. A determination step of determining whether or not a quantization value included in (for example, history information or a parameter) is used for quantization (for example, the processing in step S3 in FIG. 11 or the processing in step S23 in FIG. 14) Processing) and the determination step, when it is determined that the quantization value is not used for quantization, the first quantization matrix (for example, FIG. 8 or the quantization matrix of FIG. 13) as a quantization matrix used for quantization (for example, the processing of step S5 of FIG. 11 or FIG. 1). In the case where it is determined that the quantization value is used for quantization by the processing of step S25) and the determination step, the second quantization matrix included in the information is selected as the quantization matrix used for quantization. (For example, the process of step S4 in FIG. 11 or the process of step S24 in FIG. 14).
[0056]
The image processing device according to claim 12 (for example, the encoding unit 161 in FIG. 5, the encoding unit 211 in FIG. 9, the encoding device 252 in FIG. 15, or the transcoder 261 in FIG. 15) An acquisition unit (for example, the history extraction unit 171 in FIG. 6 or the parameter input unit 221 in FIG. 10) for acquiring information (for example, history information or a parameter) regarding encoding performed in the past on the data; An orthogonal transform unit for orthogonally transforming image data (for example, DCT unit 175 in FIG. 6 or 10), and a first quantization matrix used when information acquired by the acquisition unit is not reused in quantization. (For example, the quantization matrix of FIG. 7 or FIG. 12), and a second quantization matrix in which each component has a value equal to or less than the first quantization matrix. (For example, the memory 185 of FIG. 6 or FIG. 10), and a determination unit (for example, a memory 185 of FIG. 6 or FIG. 10) for determining a quantization value and a quantization matrix used for quantization. For example, a quantization unit (for example, FIG. 6 or FIG. 10) that performs quantization using the quantization value and the quantization matrix determined by the determination unit by the rate setting unit 177 of FIG. 6 or FIG. And a deciding unit 176), and when the information is reused and the quantized value included in the information acquired by the acquiring unit is reusable, the information acquired by the acquiring unit is Is determined to be used for quantization, and if the information is reused and the quantization value included in the information is not reusable, the third quantization matrix is stored in the storage unit. Determining that the second quantization matrix is used for quantization, and determining that the first quantization matrix stored in the storage unit is used for quantization when the information is not reused. I do.
[0057]
An image processing method according to claim 13, a program recorded on a recording medium according to claim 14, and a program according to claim 15, which are information relating to encoding performed on image data in the past. (For example, the process of step S1 in FIG. 11 or the process of step S21 in FIG. 14) for determining whether or not to reuse (for example, history information or a parameter); When it is determined that the information of the past encoding is not reused by the processing of the determining step of, the predetermined first quantization matrix (for example, the quantization matrix of FIG. 7 or 12) is used for quantization. A first selection step of selecting a quantization matrix (for example, the processing of step S2 in FIG. 11 or the processing of step S22 in FIG. 14) and a first determination step When it is determined that the information on the past encoding is reused by the processing of the step (a), a second determination step (for example, to determine whether or not the quantized value included in the information is used for the quantization (for example, If it is determined that the quantization value is not used for quantization by the processing of step S3 of FIG. 11 or the processing of step S23 of FIG. The second selection step of selecting a second quantization matrix having a value equal to or less than the quantization matrix (for example, the quantization matrix of FIG. 8 or 13) as a quantization matrix used for quantization (for example, FIG. 11). If the quantization value is determined to be used for quantization by the processing in step S5 of the above or the processing in step S25 in FIG. 14) and the processing in the second determination step, the third information included in the information is determined. The quantization matrix, characterized in that it comprises a third selection step of selecting a quantization matrix used for quantization (for example, step S4 in FIG. 11, or the process of step S24 in FIG. 14).
[0058]
The information processing device according to claim 16 (for example, the encoding unit 161 in FIG. 5, the encoding unit 211 in FIG. 9, the encoding device 252 in FIG. 15, or the transcoder 261 in FIG. 15) supplies Decoding means (for example, the decoding unit 121 in FIG. 5, the decoding unit 141 in FIG. 9, or the decoding device 251 in FIG. 15) for completely or incompletely decoding the decoded image data; Encoding means (for example, the encoding unit 161 in FIG. 5, the encoding unit 211 in FIG. 9, or the encoding unit 211 in FIG. Encoding device 252), and the encoding unit acquires information (for example, history information or a parameter) related to encoding performed on image data in the past. The history extracting unit 171 in FIG. 6 or the parameter input unit 221 in FIG. 10), orthogonal transform means for orthogonally transforming image data (for example, the DCT unit 175 in FIG. 6 or FIG. 10), and the high-frequency component is 255 A storage unit (for example, the memory 185 of FIG. 6 or 10) for storing a first quantization matrix (for example, the quantization matrix of FIG. 8 or 13) having a value less than Quantization is performed using a determination unit (for example, the rate setting unit 177 in FIG. 6 or FIG. 10) that determines a quantization value and a quantization matrix to be obtained, and the quantization value and the quantization matrix determined by the determination unit. (For example, the quantization unit 176 of FIG. 6 or FIG. 10), and the determination unit reuses the quantization value included in the information acquired by the acquisition unit. If the quantization value included in the information is not reusable, the second quantization matrix included in the information acquired by the acquisition unit is determined to be used for quantization. Determining that the first quantization matrix is used for quantization.
[0059]
The information processing device according to claim 17 (for example, the SDIT CP-ASI conversion device 151 in FIG. 5 or the Long GOP encoding device 201 in FIG. 9) decodes the supplied image data completely or incompletely. The decoding unit (for example, the decoding unit 121 in FIG. 5, the decoding unit 141 in FIG. 9, or the decoding device 251 in FIG. 15) and the image data completely or incompletely decoded by the decoding unit Encoding means (for example, the encoding unit 161 in FIG. 5, the encoding unit 211 in FIG. 9, or the encoding device 252 in FIG. 15) for encoding by a method corresponding to the state of decoding; Means for acquiring information (for example, history information or parameters) relating to encoding performed on image data in the past (for example, the history extracting unit 17 in FIG. 6) Or the parameter input unit 221 in FIG. 10), orthogonal transform means for orthogonally transforming the image data (for example, the DCT unit 175 in FIG. 6 or FIG. 10), and the information acquired by the acquisition means in the quantization is reproduced. A first quantization matrix used when not used (eg, the quantization matrix of FIG. 7 or FIG. 12) and a second quantization matrix (eg, each component having a value equal to or less than the first quantization matrix). , The quantization matrix of FIG. 8 or FIG. 13 (for example, the memory 185 of FIG. 6 or FIG. 10), and the determination unit for determining the quantization value and the quantization matrix used for quantization (for example, Using the rate setting unit 177) of FIG. 6 or FIG. 10 and the quantization value and the quantization matrix determined by the determination unit, the quantization for performing the quantization is performed. Means (for example, the quantizing unit 176 of FIG. 6 or FIG. 10), wherein the determining means enables the information to be reused and the quantized value included in the information acquired by the acquiring means to be reusable. If it is determined that the third quantization matrix included in the information acquired by the acquisition unit is used for quantization, the information is reused, and the quantization value included in the information is not reusable. If not, it is decided to use the second quantization matrix stored in the storage means for quantization, and if the information is not reused, the first quantization matrix stored in the storage means is used for quantization. Determining to use.
[0060]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0061]
FIG. 5 is a block diagram showing a configuration of a system to which the present invention is applied, which can perform frame editing after encoding uncompressed data into MPEG Long GOP stream data.
[0062]
Parts corresponding to those in the conventional case described with reference to FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In other words, in a system to which the present invention is applied and in which frames can be edited after encoding uncompressed data into MPEG Long GOP stream data, the SDTI CP-ASI converter 102 is replaced with the SDTI CP The configuration is basically the same as the conventional case described with reference to FIG. 3 except that the -ASI conversion device 151 is provided. The SDTI CP-ASI conversion device 151 replaces the encoding unit 122. , An encoding unit 161 capable of selecting an optimal quantization matrix and executing a quantization process based on whether a quantized value can be reused is provided. The configuration is basically the same as that of the conversion device 102.
[0063]
The ASI-SDTI CP converter 101 receives supply of MPEG Long GOP (ASI stream) encoded and generated by the SDI-ASI converter 1.
[0064]
An MPEG Long GOP is composed of pictures of three types of pictures (I picture, P picture, and B picture). The ASI-SDTI CP converter 101 decodes the supplied MPEG Long GOP stream data once in the decoding unit 111, and then in the encoding unit 112, encodes all the data into intra frames. In the processing, when these stream data are re-encoded by Long GOP, it is assumed that video data having the feature of I picture, P picture, or B picture is encoded by another picture type. In order to prevent this, the parameters such as the picture type and the quantization value of the coding performed in the past, that is, the coding by the SDI-ASI conversion device 1 are all set as the SMPTE328M history information (History data), and the SDTI- of the intra frame is all used. Add on CP stream and Supplied to the arm editing apparatus 3.
[0065]
The stream data with the history information edited by the frame editing device 3 is supplied to the SDTI CP-ASI conversion device 151. In the SDTI CP-ASI conversion device 151, the decoding unit 121 decodes the supplied stream data of all intra frames with history information. The encoding unit 161 re-encodes it into a Long GOP using parameters such as a picture type and a quantization value included in the decoded history information as necessary, and outputs the Long GOP.
[0066]
FIG. 6 is a block diagram illustrating a configuration of the encoding unit 161.
[0067]
The history extracting unit 171 extracts the history information from the SDIT CP stream with the history information of SMPTE 328M decoded by the decoding unit 121 and supplies the history information to the rate setting unit 177, and also converts the video stream to the video rearranging unit 172. Supply. The history information includes, for example, information on encoding performed in the past, such as a picture type, a quantization value, a motion vector, or a quantization matrix.
[0068]
The video rearranging unit 172 rearranges each frame image of the sequentially input image data as necessary, and converts each frame image of the image data to a luminance signal of 16 pixels × 16 lines and a luminance signal. It generates macroblock data divided into macroblocks composed of color difference signals to be supplied to the calculation unit 173 and the motion vector detection unit 174.
[0069]
The motion vector detection unit 174 receives the input of the macroblock data, calculates a motion vector of each macroblock based on the macroblock data and the reference image data stored in the frame memory 183, and calculates the motion vector as motion vector data. , To the motion compensator 182.
[0070]
The calculation unit 173 performs motion compensation on the macroblock data supplied from the video rearrangement unit 172 based on the image type of each macroblock. Specifically, the operation unit 173 performs motion compensation on the I picture in the intra mode, performs motion compensation on the P picture in the forward prediction mode, and performs bidirectional motion on the B picture. Motion compensation is performed in the prediction mode.
[0071]
Here, the intra mode is a method in which a frame image to be encoded is directly used as transmission data, and the forward prediction mode is a method in which a prediction residual between the frame image to be encoded and a past reference image is transmitted data. The bidirectional prediction mode is a method in which a prediction residual between a frame image to be encoded and past and future reference images is used as transmission data.
[0072]
First, when the macroblock data is an I picture, the macroblock data is processed in the intra mode. That is, the arithmetic unit 173 sends the macroblock of the input macroblock data as it is to the DCT (Discrete Cosine Transform: discrete cosine transform) unit 175 as arithmetic data. The DCT unit 175 converts the input operation data into DCT coefficients by performing a DCT transform process, which is an orthogonal transform, and sends the result to the quantization unit 176 as DCT coefficient data.
[0073]
The quantization unit 176 performs quantization processing on the input DCT coefficient data based on the quantization value Q and the quantization matrix supplied from the rate setting unit 177, and obtains a VLC (Variable Length) as a quantization DCT coefficient. Code; variable length coding) section 178 and an inverse quantization section 179. The quantization unit 176 calculates the quantized DCT coefficient Sq using the following equation (1).
[0074]
Sq = ((32 × S) / q) / (2 × Q) (1)
[0075]
However, in equation (1), the DCT coefficient component value before quantization is S, the component value of the quantization matrix is q, and the result of the multiplication is rounded off.
[0076]
The quantized DCT coefficient data sent to the inverse quantization unit 179 undergoes an inverse quantization process using the same quantization step size as the quantization unit 176, and is sent to the inverse DCT unit 180 as DCT coefficient data. The inverse quantization unit 179 calculates the inverse quantized DCT coefficient Siq using the following equation (2).
[0077]
Siq = (2 × Sq × q × Q) / 32 (2)
[0078]
The inverse DCT unit 180 performs an inverse DCT process on the supplied DCT coefficient data, and the generated operation data is sent to the operation unit 181 and stored in the frame memory 183 as reference image data.
[0079]
When the macroblock data is a P-picture, the arithmetic unit 173 performs a motion compensation process in the forward prediction mode on the macroblock data. To perform motion compensation processing.
[0080]
The motion compensation unit 182 performs motion compensation on the reference image data stored in the frame memory 183 according to the motion vector data, and calculates forward predicted image data or bidirectional predicted image data. The calculation unit 173 performs a subtraction process on the macroblock data using the forward prediction image data or the bidirectional prediction image data supplied from the motion compensation unit 182.
[0081]
That is, in the forward prediction mode, the motion compensation unit 182 reads the reference image data by shifting the read address of the frame memory 183 in accordance with the motion vector data, and uses the read image data as the forward prediction image data. It is supplied to the arithmetic unit 181. The operation unit 173 subtracts the forward prediction image data from the supplied macroblock data to obtain difference data as a prediction residual. Then, the arithmetic unit 173 sends the difference data to the DCT unit 175.
[0082]
The calculation unit 181 is supplied with forward prediction image data from the motion compensation unit 182, and the calculation unit 181 adds the forward prediction image data to the calculation data supplied from the inverse DCT unit to perform reference. The image data is locally reproduced and output to the frame memory 183 for storage.
[0083]
Further, in the bidirectional prediction mode, the motion compensation unit 182 reads the reference image data by shifting the read address of the frame memory 183 according to the motion vector data, and uses this as the bidirectional prediction image data. It is supplied to the arithmetic unit 181. The operation unit 173 subtracts the bidirectional predicted image data from the supplied macroblock data to obtain difference data as a prediction residual. Then, the arithmetic unit 173 sends the difference data to the DCT unit 175.
[0084]
The operation unit 181 is supplied with bidirectional predicted image data from the motion compensation unit 182, and the operation unit 181 adds the bidirectional predicted image data to the operation data supplied from the inverse DCT unit to obtain a reference. The image data is locally reproduced and output to the frame memory 183 for storage.
[0085]
Thus, the image data input to the encoding unit 161 undergoes motion compensation prediction processing, DCT processing, and quantization processing, and is supplied to the VLC unit 178 as quantized DCT coefficient data. VLC section 178 performs variable-length encoding processing on the quantized DCT coefficient data based on a predetermined conversion table, and sends the resulting variable-length encoded data to buffer 184. The buffer 184 buffers the supplied variable-length coded data and then outputs the data.
[0086]
The rate setting unit 177 constantly monitors the accumulation state of the variable-length encoded data stored in the buffer 184, and based on the occupancy information indicating the accumulation state or the history information supplied from the history extraction unit 171. The quantization step size is determined.
[0087]
At this time, the rate setting unit 177 determines whether the quantization matrix included in the history information supplied from the history extraction unit 171 or the plurality of quantization matrices stored in the memory 185 has a coding An item that meets the conditions is selected.
[0088]
In the memory 185, in addition to the intra quantization matrix and the non-intra (inter) quantization matrix (FIG. 12) which are defaulted in MPEG2 shown in FIG. Intra-quantization matrices used when the quantization value of the information cannot be reused are stored.
[0089]
As described above, when re-encoding using past encoding information, for example, the bit rate may be reduced by re-encoding, or depending on the state of the VBV buffer at the time of encoding a stream including edit points. In some cases, it is not possible to reuse a quantization value in past encoding. In order to prevent image quality degradation caused by the inability to reuse quantization values in the past encoding, an intra quantization matrix capable of protecting the frequency component by reducing the value of the AC component is used for re-encoding. What is necessary is just to use it.
[0090]
FIG. 7 shows an intra quantization matrix set as a default in MPEG2. The intra quantization matrix of FIG. 7 is set so that the higher the AC component in the high frequency band, the larger the value. This utilizes the characteristic that human vision is insensitive to deterioration of the high-frequency component image, and divides the high-frequency component by a larger value without deteriorating the appearance of the image. This is because it is possible to greatly reduce the amount. As the DCT coefficient before quantization, the DC component tends to be a large value and the AC component tends to be a small value. Therefore, as shown in FIG. In many cases, the coefficients after quantization have almost zero high-frequency components. Note that, in MPEG2, the maximum value that can be taken by each component of the quantization matrix is 255.
[0091]
However, when the video data includes many high-frequency components such as noise and fine textures, the coefficients remain in the high-frequency components of the DCT coefficients before quantization, and the value of the coefficient is often 1. When such video data is decoded and re-encoded, it is possible to use the same quantization matrix as in the past encoding, and if the quantized value is the same as in the past encoding, The converted coefficient also becomes 1, and can be decoded again to the original value. However, as described above, when the quantized value becomes, for example, about twice as large as the past encoding, the value after decoding after re-encoding greatly differs from the value before decoding before. May occur.
[0092]
In this way, the value of many components fluctuates, so that the image quality is significantly degraded. Further, if the re-encoding is repeated for such video data, the same fluctuation of the decoded value is repeated, so that each time the re-encoding is performed, the image quality further deteriorates. I will.
[0093]
Therefore, even in the high-frequency AC component, a large value is not set, and the re-encoding is performed by using a quantization matrix in which the high-frequency component is equal to or substantially equal to the low-frequency component. At the time of quantization, the value immediately before division by the quantization value can be set to a somewhat large value, so that it is possible to prevent the above-mentioned influence of the fluctuation of the decoding value due to the fluctuation of the quantization value. For example, as shown in FIG. 8, using a quantization matrix in which all the components other than the DC component defined as “8” in the MPEG2 standard are set to 16 which is twice the value of the DC component. Thus, it is possible to prevent the influence of the fluctuation of the decoded value due to the fluctuation of the quantization value described above.
[0094]
When the intra quantization matrix that is the default in MPEG2 shown in FIG. 7 is used, the DCT coefficient component value before quantization is 9 in the past encoding, and the quantization matrix value of the corresponding component is 9 Is q = 34 and the quantized value is Q = 4, the quantization result is Sq = ((32 × 9) / 34) / (2 × 4) = 1 from the above equation (1). When inverse quantization is performed, Seq = (2 × 1 × 34 × 4) / 32 = 9 from the above equation (2).
[0095]
At this time, if the quantization value Q is doubled from Q = 4 to Q = 8 at the time of re-encoding, the quantization result is similarly calculated from Expression (1) as Sq = ((32 × 9 ) / 34) / (2 × 8) = 1, and when inversely quantized, from equation (2), Siq = (2 × 1 × 34 × 8) / 32 = 17, and the DCT coefficient component value before quantization 9 is a greatly different value.
[0096]
On the other hand, for example, when the quantization matrix of FIG. 8 is used for re-encoding, since the quantization matrix value of the corresponding component is q = 16, the quantization value Q is changed from Q = 4 to 2 Even if Q = 8 times, the quantization result at the time of re-encoding is Sq = ((32 × 9) / 16) / (2 × 8) = 1 from Expression (1), and the inverse quantum From the equation (2), Siq = (2 × 1 × 16 × 8) / 32 = 8. That is, when the quantization matrix shown in FIG. 8 is used for re-encoding, a DCT coefficient component value before quantization of 9 can be obtained, which is an inverse quantization result that does not change much. It turns out that it is hard to be influenced by the fluctuation of the decoded value due to the fluctuation.
[0097]
Therefore, when the quantized value cannot be reused, a large value is not set even in the high-frequency AC component as shown in FIG. 8 (the value of the high-frequency AC component is twice the value of the DC component). By using an intra quantization matrix that is limited to the following and has a value equal to or substantially equal to the value of the low-frequency AC component), image quality degradation after re-encoding can be suppressed.
[0098]
Here, a large value is not set for the high-frequency AC component, and the intra-quantization matrix of FIG. 8 is configured such that the high-frequency component has the same or substantially the same value as the low-frequency component. Although described as an example of the quantization matrix, the intra quantization matrix used in the present invention is not limited to the intra quantization matrix of FIG. 8, but has an AC component like the intra quantization matrix of FIG. Even if the values are not all the same, for example, a sufficiently small value may be used so that the high-frequency component is twice or less the DC component.
[0099]
The rate setting unit 177 performs encoding using history information based on a signal indicating a user operation input supplied from an operation input unit (not shown) or whether history information is supplied from the history extraction unit 171. Determine whether it is possible to do so. As described above, the history information supplied from the history extraction unit 171 includes, for example, a picture type, a quantization value, a motion vector, or a quantization matrix.
[0100]
If the rate setting unit 177 determines that encoding cannot be performed using the history information, the rate setting unit 177 reads the intra quantization matrix used in normal encoding described with reference to FIG. This is supplied to the quantization unit 176. A method of determining the quantization value Q when it is determined that encoding cannot be performed using the history information will be described later.
[0101]
If the rate setting unit 177 determines that encoding can be performed using the history information, whether the quantization value can be reused based on the history information supplied from the history extraction unit 171 Determine whether or not.
[0102]
Here, whether or not the quantized value can be reused may be determined by, for example, whether or not the quantized value can be reused by a user, or whether the quantized value can be reused. The information indicating whether or not the quantization value can be reused may be described therein, or the previously encoded image frame indicated in the history information and the Whether the image frame at the time of encoding matches the position and size, whether the bit rate in the previous encoding indicated in the history information is smaller than the bit rate of the current encoding, Alternatively, it may be determined according to a predetermined condition such as whether or not the chroma format in the previous encoding is larger than the current chroma format.
[0103]
Then, when it is determined that the quantization value can be reused, the rate setting unit 177 supplies the quantization matrix included in the history information to the quantization unit 176. On the other hand, if it is determined that it is not possible to reuse the quantization value, the rate setting unit 177 reads the quantization matrix described with reference to FIG. , To the quantization unit 176.
[0104]
Further, when the history information is not used, or when the quantized value included in the history information cannot be reused, the rate setting unit 177 determines the generated code amount of the macroblock actually generated from the target generated code amount. When the number of generated codes is large, the quantization step size is increased to reduce the generated code amount, and when the actual generated code amount is smaller than the target generated code amount, the quantization step size is reduced to increase the generated code amount. It has been made.
[0105]
That is, the rate setting unit 177 obtains the buffer occupancy of the virtual buffer by assuming the transition of the accumulation state of the variable-length coded data stored in the VBV buffer provided on the decoder side, and obtains the quantization value Q Is calculated and supplied to the quantization unit 176 together with the quantization matrix described with reference to FIG.
[0106]
The buffer occupancy d (j) of the virtual buffer in the j-th macroblock is expressed by the following equation (3). The buffer occupancy d (j + 1) of the virtual buffer in the j + 1-th macroblock is The buffer occupancy d (j + 1) of the virtual buffer in the (j + 1) th macroblock is expressed by the following expression (5) by expressing expression (4) and subtracting expression (4) from expression (3). You.
[0107]
d (j) = d (0) + B (j−1) − {T × (j−1) / MBcnt} (3)
[0108]
Here, d (0) is the initial buffer capacity, B (j) is the number of bits generated in the j-th macroblock, MBcnt is the number of macroblocks in the picture, and T is the target generation in picture units. The code amount.
[0109]
d (j + 1) = d (0) + B (j) − (T × j) / MBcnt (4)
[0110]
d (j + 1) = d (j) + {B (j) -B (j-1)}-T / MBcnt (5)
[0111]
When the macroblock in the picture is divided into, for example, an intra slice portion and an inter slice portion, the rate setting section 177 assigns the target to the macro block in the intra slice portion and each macro block in the inter slice portion. The generated code amounts Tpi and Tpp can be individually set.
[0112]
Therefore, the rate setting unit 177 substitutes the buffer occupation amount d (j + 1) and the constant r shown in the equation (6) into the equation (7) to obtain the quantization index data Q of the macroblock (j + 1). (J + 1) is calculated and supplied to the quantization unit 176.
[0113]
r = (2 × br) / pr (6)
Q (j + 1) = d (j + 1) × (31 / r) (7)
Here, br is a bit rate, and pr is a picture rate.
[0114]
The quantization unit 176 determines the quantization step size in the next macroblock based on the quantization value Q supplied from the rate setting unit 177, and quantizes the DCT coefficient data according to the quantization step size.
[0115]
Accordingly, the quantization unit 176 can quantize the DCT coefficient data by the quantization step size that is calculated based on the actual generated code amount and is optimal for the target generated code amount of the next picture.
[0116]
Thus, the quantization unit 176 can quantize the buffer 184 according to the data occupancy of the buffer 184 so that the buffer 184 does not overflow or underflow, and quantize the decoder-side VBV buffer so that it does not overflow or underflow. Quantized DCT coefficient data can be generated.
[0117]
In the above description, the case where the encoding process is performed in units of pictures has been described. However, even when the encoding process is performed not in units of pictures but in units of slices or macroblocks, basically, Similarly, an encoding process is performed.
[0118]
In addition, when the input image is encoded at a high bit rate into an MPEG Long GOP described with reference to FIG. 4 and then decoded and re-encoded to a low bit rate Long GOP, an image for re-encoding may be used. The present invention can be similarly applied to a system in which deterioration does not occur. FIG. 9 illustrates a case where an input image is encoded into an MPEG Long GOP at a high bit rate and decoded and re-encoded to a low bit rate Long GOP to which the present invention is applied. FIG. 1 is a block diagram showing a configuration of a system in which image degradation for re-encoding does not occur. Parts corresponding to those in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0119]
That is, the system in FIG. 9 includes a Long GOP encoding device 201 instead of the Long GOP encoding device 131, and the Long GOP encoding device 201 replaces the encoding unit 142 with a quantization using an optimal quantization matrix. The configuration is basically the same as that of the Long GOP encoding device 131 except that an encoding unit 211 capable of performing encoding is provided.
[0120]
When the Long GOP encoding device 201 supplied with the MPEG Long GOP stream (ASI stream) data encoded by the Long GOP encoding device 51 decodes the high bit rate MPEG Long GOP by the decoding unit 141, Then, necessary encoding parameters are acquired, and the decoded video data and the acquired encoding parameters are supplied to the encoding unit 211. The encoding unit 211 encodes the video data using the supplied encoding parameters as necessary, so as to be a Long GOP of low bit rate MPEG, and encodes the encoded low bit rate MPEG. Outputs Long GOP stream (ASI stream) data.
[0121]
FIG. 10 is a block diagram illustrating a configuration of the encoding unit 211. Note that, in FIG. 10, the portions corresponding to the encoding unit 161 in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.
[0122]
That is, the encoding unit 211 includes a parameter input unit 221 that omits the history extraction unit 171 and obtains the parameters supplied from the decoding unit 141 and supplies the parameters to the rate setting unit 177. Has basically the same configuration as the encoding unit 161.
[0123]
The rate setting unit 177 constantly monitors the accumulation state of the variable-length encoded data stored in the buffer 184, and based on the occupancy information indicating the accumulation state or the parameter information supplied from the parameter input unit 221. The quantization step size is determined.
[0124]
The rate setting unit 177 performs encoding using parameter information based on a signal indicating a user operation input supplied from an operation input unit (not shown) or whether parameter information is supplied from the parameter input unit 221. It is determined whether or not to perform. The parameter information supplied from the parameter input unit 221 includes, for example, a picture type, a quantization value, a motion vector, or a quantization matrix, like the above-described history information.
[0125]
If the rate setting unit 177 determines that the encoding cannot be performed using the parameter information, the rate setting unit 177 reads out the quantization matrix described with reference to FIG. To the conversion unit 176.
[0126]
If the rate setting unit 177 determines that encoding can be performed using the parameter information, it is possible to reuse the quantization value based on the parameter information supplied from the parameter input unit 221. Determine whether or not.
[0127]
Here, whether or not the quantized value can be reused may be determined by, for example, whether or not the quantized value can be reused by a user, In the information, whether or not the quantization value can be reused may be described, or the previously encoded image frame indicated in the parameter information may be described. Whether the image frame at the time of encoding matches the position and size, whether the bit rate in the previous encoding indicated in the parameter information is smaller than the bit rate of the current encoding, Alternatively, it is determined by a predetermined condition such as whether or not the chroma format in the previous encoding is larger than the current chroma format.
[0128]
Then, when it is determined that the quantization value can be reused based on the parameter information, the rate setting unit 177 supplies the intra quantization matrix included in the parameter information to the quantization unit 176. On the other hand, if it is determined that the quantization value cannot be reused, the rate setting unit 177 reads the intra quantization matrix described with reference to FIG. Then, the signal is supplied to the quantization unit 176.
[0129]
The quantization unit 176 quantizes the DCT coefficient supplied from the DCT unit 175 based on the quantization value and the quantization matrix supplied from the rate setting unit 177.
[0130]
Next, with reference to the flowchart of FIG. 11, the quantization matrix determination processing 1 executed in the encoding unit 161 of FIG. 6 or the encoding unit 211 of FIG. 10 will be described.
[0131]
In step S 1, the rate setting unit 177 is based on a signal indicating a user operation input supplied from an operation input unit (not shown), or history information from the history information extraction unit 171, or a parameter from the parameter input unit 221. It is determined whether or not encoding is performed by reusing the past encoding information described in the history information or the parameter based on whether or not the encoding is supplied.
[0132]
If it is determined in step S1 that the information of the past encoding is not reused to perform the encoding, in step S2, the rate setting unit 177 uses the normal encoding, which will be described with reference to FIG. The obtained intra quantization matrix is read from the memory 185 and supplied to the quantization unit 176, and the processing is terminated.
[0133]
If it is determined in step S1 that the encoding is performed by reusing the information of the past encoding, in step S3, the rate setting unit 177 sets, for example, in advance that the quantization value cannot be reused. Whether the quantization value can be reused in the history information or the parameter information, and whether the previous coding indicated in the history information or the parameter information is executed. Whether or not the image frame at the time of re-encoding matches the position and size of the image frame, and the bit rate in the previous encoding indicated in the history information and the parameter information is the current encoding. Satisfies certain conditions, such as whether the bit rate is lower than the current bit rate, or whether the chroma format in the previous encoding is higher than the current chroma format. Based on whether or not the quantization value determines whether reusable.
[0134]
If it is determined in step S3 that the quantized value is reusable, in step S4, the rate setting unit 177 supplies the history information supplied from the history information extraction unit 171 or the history information supplied from the parameter input unit 221. The intra quantization matrix in the past encoding, which is included in the parameters, is supplied to the quantization unit 176, and the process ends.
[0135]
If it is determined in step S3 that the quantization value is not reusable, in step S5, the rate setting unit 177 converts the intra quantization matrix stored in the memory 185 and described with reference to FIG. The data is supplied to the quantization unit 176, and the processing ends.
[0136]
By such processing, when the quantization value used for encoding is different from the quantization value of the past encoding, when the bit rate becomes small or when the input video data at the time of re-encoding is Even when the input video data is different from the input video data, it is possible to prevent flicker caused by emphasizing high frequency components or reducing the resolution of an image, particularly in an I picture.
[0137]
Further, in the processing described above, if the quantization value is not reusable among the information on the past encoding, a large value is not used for the AC component (particularly, the high-frequency portion of the AC component). Although the intra quantization matrix is selected and described as being used for quantization, the quantization value can be reused not only for the intra matrix but also for the non-intra (inter) quantization matrix by the same processing. The best one may be selected based on whether or not there is.
[0138]
That is, in addition to the non-intra quantization matrix shown as a default in the MPEG2 TM5 shown in FIG. 12 in the encoding unit 161 of FIG. 6 or the memory 185 of the encoding unit 211 of FIG. The non-intra quantization matrix that does not use a large value in the high-frequency AC component is further stored, and the rate control unit 177 determines whether the quantization value can be reused based on whether the quantization value is reusable. The best one can be selected.
[0139]
FIG. 12 shows a non-intra quantization matrix set as a default in TM5 of MPEG2. The non-intra quantization matrix in FIG. 12 also uses the characteristic that human vision is insensitive to deterioration of the high-frequency component image, so that the high-frequency component is divided by a larger value. The AC component in the range is set to have a larger value.
[0140]
Even in the non-intra quantization matrix, a large value is not used even in the high-frequency AC component, and by using a quantization matrix in which the high-frequency component is equal to or substantially equal to the low-frequency component, At the time of re-encoding, the value immediately before the division by the quantization value increases, so that it is possible to prevent the influence of the fluctuation of the decoding value due to the fluctuation of the quantization value. For example, as shown in FIG. 13, by using a quantization matrix in which all the components are 16, it is possible to prevent the influence of the above-described fluctuation of the quantization value from the fluctuation of the decoded value.
[0141]
Here, FIG. 13 shows an example of a non-intra quantization matrix in which a large value is not used for the high-frequency AC component and the high-frequency component has the same or substantially the same value as the low-frequency component. Has been described using a quantization matrix in which all components are the same, but the non-intra quantization matrix used in the present invention is not limited to the non-intra quantization matrix of FIG. Even if not all the components or all the AC components have the same value as in the case of an intra quantization matrix, the high-frequency component has a sufficiently small value that is, for example, twice or less the DC component, It suffices that a value having a smaller high-frequency component (for example, 32 or less) than the non-intra quantization matrix described using No. 12 is used.
[0142]
Next, referring to the flowchart of FIG. 14, based on whether or not the quantized value, which is executed in the encoding unit 161 of FIG. 6 or the encoding unit 211 of FIG. 10, is reusable. The following describes a quantization matrix determination process 2 for selecting an intra quantization matrix and a non-intra quantization matrix.
[0143]
In step S <b> 21, the rate setting unit 177 is based on a signal indicating a user's operation input, which is supplied from an operation input unit (not shown), or history information from the history information extraction unit 171, or a parameter from the parameter input unit 221. It is determined whether or not encoding is performed by reusing the past encoding information described in the history information or the parameter based on whether or not the encoding is supplied.
[0144]
In step S21, when it is determined that the encoding is not performed by reusing the information of the past encoding, in step S22, the rate setting unit 177 is used in normal encoding, which will be described with reference to FIG. The obtained intra quantization matrix and the non-intra quantization matrix described with reference to FIG. 12 are read from the memory 185 and supplied to the quantization unit 176, and the process is terminated.
[0145]
If it is determined in step S21 that the encoding is performed by reusing the information of the past encoding, in step S23, the rate setting unit 177 sets, for example, in advance that the quantization value cannot be reused. Whether the quantization value can be reused in the history information or the parameter information, and whether the previous coding indicated in the history information or the parameter information is executed. Whether or not the image frame at the time of re-encoding matches the position and size of the image frame, and the bit rate in the previous encoding indicated in the history information and the parameter information is the current encoding. Predetermined conditions, such as whether the bit rate is lower than the bit rate of the previous or whether the chroma format in the previous encoding is higher than the current chroma format Based on whether or not satisfied, the quantization value determines whether reusable.
[0146]
If it is determined in step S23 that the quantized value is reusable, in step S24, the rate setting unit 177 supplies the history information supplied from the history information extracting unit 171 or the history information supplied from the parameter input unit 221. The intra-quantization matrix and the non-intra-quantization matrix in the past encoding, which are included in the parameters, are supplied to the quantization unit 176, and the process ends.
[0147]
If it is determined in step S23 that the quantization value is not reusable, in step S25, the rate setting unit 177 stores the intra quantization matrix stored in the memory 185 and described with reference to FIG. The non-intra quantization matrix described with reference to FIG. 13 is supplied to the quantization unit 176, and the process ends.
[0148]
By such processing, when the quantization value used for encoding is different from the quantization value of the past encoding, when the bit rate becomes small or when the input video data at the time of re-encoding is Even when the input video data is different from the input video data, it is possible to prevent the flicker caused by the reduction of the resolution of the image of the I picture, and to prevent the deterioration of the image even in the non-intra part. can do.
[0149]
Although the above description has been made on the assumption that a quantization matrix (standard default) used as a standard in an encoding device is used as a quantization matrix used when information on past encoding is not reused. Regardless of the value of the quantization matrix (for example, quantization matrix A) used when information on past encoding is not reused (for example, the highest possible high-frequency component in the MPEG standard). ), The present invention reuses information on past encoding but does not reuse quantization values of past encoding. For example, the quantization matrix B) has a smaller high-frequency component than the quantization matrix A (at least, Can achieve the effect that if a quantization matrix) composed of a value less than 255, to prevent image deterioration.
[0150]
That is, when the quantization value used for encoding is different from the quantization value of the past encoding, the quantization matrix B is used for the quantization, and the bit number is compared with the case where the quantization matrix A is used. Even when the rate becomes small or when the input video data at the time of re-encoding is different from the input video data at the time of past encoding, the flicker generated due to a decrease in the resolution of an I-picture image, etc. Can be prevented, and image degradation can be prevented.
[0151]
In the present invention, for example, only a P picture is used without using a B picture which causes a reordering delay and an I picture having a large generated code amount. The present invention is applicable to a case where low-delay encoding is performed so that encoding can be performed without reordering by dividing a slice into inter-slices including all remaining slices.
[0152]
In addition, the present invention employs all frame images as P pictures as low-delay coding. For example, within the picture frame size of 45 horizontal macroblocks and 24 vertical macroblocks, two macroblocks from the top of the frame image and 45 macroblocks Even when the area for a block is set as one intra-slice part and all the others are set as an inter-slice part, other various types such as setting the intra-slice part to an area for one vertical macroblock and 45 horizontal macroblocks are used. The present invention is also applicable to a case of forming a region having a size of
[0153]
Furthermore, in the above-described embodiment, a case has been described in which the present invention is applied to the encoding unit 161 or the encoding unit 211 that performs compression encoding by the MPEG method. However, the present invention is not limited to this. Alternatively, the present invention may be applied to an encoding device using various other image compression methods.
[0154]
Note that, in the above-described embodiment, the description has been made assuming that each of the conversion devices for converting stream data and the Long GOP encoding device has a decoding unit and an encoding unit, respectively. The present invention is applicable even when the units are configured as independent devices as a decoding device and an encoding device, respectively.
[0155]
That is, in the above-described embodiment, the description has been given assuming that each of the conversion devices and the Long GOP encoding device converts the stream data. However, for example, as shown in FIG. The decoding device 251 for converting to a signal and the coding device 252 for coding a baseband signal and converting it to stream data may be configured as independent devices. Further, even when the decoding device 251 does not completely decode the supplied stream data and the corresponding encoding device 252 partially encodes the corresponding portion of the incompletely decoded data, the present invention is also applicable. The invention is applicable.
[0156]
For example, if the decoding device 251 performs only decoding and inverse quantization on a VLC code and does not perform inverse DCT transform, the encoding device 252 performs quantization and variable length encoding processing. No processing is performed. The present invention can be applied to the determination of whether or not to reuse the quantization value in the quantization of the encoding device 252 that performs such partial encoding (encoding from an intermediate stage). Needless to say.
[0157]
Further, when the encoding device 252 encodes the baseband signal completely decoded by the decoding device 251 to an intermediate stage (for example, performs DCT transform and quantization but does not perform variable length encoding processing), Since the decoding device 251 has not completely decoded (for example, only performs decoding and inverse quantization on the VLC code and has not performed the inverse DCT transform), the decoding device 251 performs coding on data that has been encoded to an intermediate stage. The present invention can also be applied to a case where the encoding device 252 further encodes to an intermediate stage (for example, performs quantization but does not perform variable length encoding).
[0158]
Further, the present invention is also applicable to a transcoder 261 including an encoding device 251 for performing such partial decoding and an encoding device 252 for performing partial encoding. Such a transcoder 261 is used, for example, when an editing device 262 that performs editing such as splicing is used.
[0159]
The series of processes described above can be executed by hardware, but can also be executed by software. In this case, for example, the SDTI CP-ASI converter 151 and the Long GOP encoder 201 are configured by a personal computer 301 as shown in FIG.
[0160]
In FIG. 16, a CPU (Central Processing Unit) 311 performs various processes according to a program stored in a ROM (Read Only Memory) 312 or a program loaded from a storage unit 318 into a RAM (Random Access Memory) 313. Execute. The RAM 313 also appropriately stores data necessary for the CPU 311 to execute various processes.
[0161]
The CPU 311, the ROM 312, and the RAM 313 are mutually connected via a bus 314. The input / output interface 315 is also connected to the bus 314.
[0162]
The input / output interface 315 includes an input unit 316 including a keyboard and a mouse, an output unit 317 including a display and a speaker, a storage unit 318 including a hard disk, and a communication unit 319 including a modem and a terminal adapter. It is connected. The communication unit 319 performs communication processing via a network including the Internet.
[0163]
A drive 320 is connected to the input / output interface 315 as needed, and a magnetic disk 331, an optical disk 332, a magneto-optical disk 333, a semiconductor memory 334, or the like is appropriately mounted, and a computer program read out from these is loaded. Are installed in the storage unit 318 as necessary.
[0164]
When a series of processing is executed by software, a program constituting the software executes various functions by installing a computer built in dedicated hardware or installing various programs. For example, it is installed from a network or a recording medium into a general-purpose personal computer or the like.
[0165]
As shown in FIG. 16, this recording medium is distributed separately from the apparatus main body to supply the program to the user, and stores the program on a magnetic disk 331 (including a floppy disk) and an optical disk 332 ( A package medium including a CD-ROM (compact disk-only memory), a DVD (including a digital versatile disk), a magneto-optical disk 333 (including an MD (mini-disk) (trademark)), or a semiconductor memory 334 is used. In addition to the configuration, the storage unit 318 includes a ROM 312 in which a program is stored, a hard disk included in the storage unit 318, and the like, which are supplied to a user in a state of being incorporated in the apparatus main body in advance.
[0166]
In this specification, the steps of describing a program stored in a recording medium may be performed in chronological order according to the order in which they are included, or may be performed in parallel or individually even if not necessarily performed in chronological order. This includes the processing to be executed.
[0167]
In the present specification, the system represents the entire device including a plurality of devices.
[0168]
【The invention's effect】
As described above, according to the present invention, image data can be encoded. In particular, when the quantization value used in the past encoding cannot be reused, the quantization can be performed using the quantization matrix in which the high frequency component is configured with a value of less than 255, It is possible to prevent the image quality from deteriorating.
[0169]
According to another embodiment of the present invention, image data can be encoded, and information used in past encoding is reused. However, when quantization values cannot be reused, past encoding is performed. Quantization can be performed using a quantization matrix composed of smaller values than the quantization matrix used when the information used in cannot be reused, so that image quality degradation is prevented. Can be.
[0170]
According to another aspect of the present invention, image data can be converted, and in a coding process in a conversion process, when a quantization value used in a past coding cannot be reused, a high-frequency component is reduced. Since the quantization can be performed using a quantization matrix having a value of less than 255 or less, it is possible to prevent the image quality from deteriorating.
[0171]
Further, according to another aspect of the present invention, image data can be converted, and information used in past coding is reused in coding processing in conversion processing, but quantization values cannot be reused. In this case, quantization can be performed using a quantization matrix composed of smaller values than a quantization matrix used when information used in past encoding cannot be reused. Deterioration can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a conventional system in which re-encoding is performed when performing frame editing.
FIG. 2 is a diagram for describing a conventional system capable of changing the bit rate of a Long GOP of MPEG and performing re-encoding.
FIG. 3 is a diagram for describing a case where encoding history information is used in a conventional system in which re-encoding is performed when performing frame editing.
FIG. 4 is a diagram for describing a case where encoding history information is used in a conventional system capable of changing the bit rate of a Long GOP of MPEG and performing re-encoding.
FIG. 5 is a block diagram illustrating a configuration of a system to which re-encoding is performed when performing frame editing, to which the present invention is applied.
FIG. 6 is a block diagram illustrating a configuration of an encoding unit in FIG. 5;
FIG. 7 is a diagram for describing an intra quantization matrix set as a default in MPEG2.
FIG. 8 is a diagram for describing an intra quantization matrix used in the present invention.
FIG. 9 is a block diagram showing the configuration of a system to which the present invention is applied and which can re-encode by changing the bit rate of an MPEG Long GOP.
FIG. 10 is a block diagram illustrating a configuration of an encoding unit in FIG. 9;
FIG. 11 is a flowchart illustrating a quantization matrix determination process 1;
FIG. 12 is a diagram for describing a non-intra quantization matrix that is set as a default in MPEG2.
FIG. 13 is a diagram illustrating a non-intra quantization matrix used in the present invention.
FIG. 14 is a flowchart illustrating a quantization matrix determination process 2;
FIG. 15 is a diagram for explaining a configuration of a different device to which the present invention can be applied.
FIG. 16 is a block diagram illustrating a configuration of a personal computer.
[Explanation of symbols]
1 SDI-ASI conversion device, 3 frame editing device, 51 Long GOP coding device, 61 decoding unit, 62 coding unit, 101 ASI-SDTI conversion device, 111 decoding unit, 112 coding unit, 121 decoding unit, 141 decoding Unit, 151 SDTI CP-ASI conversion unit, 161 encoding unit, 171 history extraction unit, 172 image rearrangement unit, 173 operation unit, 174 motion vector detection unit, 175 DCT unit, 176 quantization unit, 177 rate setting unit, 178 VLC section, 179 inverse quantization section, 180 inverse DCT section, 181 operation section, 182 motion compensation section, 183 frame memory, 184 buffer, 185 memory, 201 Long GOP encoding apparatus, 211 encoding section, 221 parameter input section

Claims (17)

In an image processing device that encodes image data,
Acquisition means for acquiring information on encoding performed in the past on the image data,
Orthogonal transformation means for orthogonally transforming the image data,
Storage means for storing a first quantization matrix in which the high-frequency component is configured with a value less than 255;
Determining means for determining a quantization value and a quantization matrix used for quantization;
Using the quantization value and the quantization matrix determined by the determination means, quantization means for performing quantization,
With
The determining unit quantizes a second quantization matrix included in the information obtained by the obtaining unit, when the quantization value included in the information obtained by the obtaining unit is reusable. And when the quantized value included in the information is not reusable, determining to use the first quantization matrix stored in the storage means for quantization. Characteristic image processing device. The image processing apparatus according to claim 1, wherein the first quantization matrix has a high-frequency component having a value equal to or less than twice a DC component. The image processing device according to claim 1, wherein the first quantization matrix has a high-frequency component having a value of 32 or less. The image processing apparatus according to claim 1, further comprising an encoding unit that encodes the quantized coefficient data quantized by the quantization unit. The image processing apparatus according to claim 1, wherein the first quantization matrix stored in the storage unit includes a quantization matrix used for quantizing an intra macroblock. The first quantization matrix stored in the storage means includes a third quantization matrix used for quantizing intra macroblocks and a fourth quantization matrix used for quantizing non-intra macroblocks. The image processing apparatus according to claim 1, wherein: The storage unit further stores a third quantization matrix used when the information acquired by the acquisition unit is not reused in quantization,
The determining means further determines whether the information obtained by the obtaining means is reused,
When the information is reused and the quantized value included in the information acquired by the acquiring unit is reusable, the determining unit is included in the information acquired by the acquiring unit. Deciding to use said second quantization matrix for quantization,
When the information is reused and the quantized value included in the information is not reusable, the determining unit converts the first quantization matrix stored in the storage unit into a quantization. Decided to use
2. The image processing apparatus according to claim 1, wherein when the information is not reused, the determination unit determines to use the third quantization matrix stored in the storage unit for quantization. apparatus. 2. The image processing apparatus according to claim 1, wherein all AC components of the first quantization matrix stored by the storage unit have the same value. In an image processing method of an image processing device that encodes image data,
A determination step of determining whether or not a quantization value included in information on encoding performed in the past on the image data is used for quantization;
When it is determined that the quantization value is not used for quantization by the processing of the determination step, a first quantization matrix in which a high-frequency component is configured with a value less than 255 is used for quantization. A first selection step of selecting as a quantization matrix;
When it is determined by the processing of the determination step that the quantization value is used for quantization, a second selection of selecting a second quantization matrix included in the information as a quantization matrix used for quantization And an image processing method. A program for causing a computer to execute a process of encoding image data,
A determination step of determining whether or not a quantization value included in information on encoding performed in the past on the image data is used for quantization;
When it is determined that the quantization value is not used for quantization by the processing of the determination step, a first quantization matrix in which a high-frequency component is configured with a value less than 255 is used for quantization. A first selection step of selecting as a quantization matrix;
When it is determined by the processing of the determination step that the quantization value is used for quantization, a second selection of selecting a second quantization matrix included in the information as a quantization matrix used for quantization And a recording medium on which a computer-readable program is recorded. A program for causing a computer to execute a process of encoding image data,
A determination step of determining whether or not a quantization value included in information on encoding performed in the past on the image data is used for quantization;
When it is determined that the quantization value is not used for quantization by the processing of the determination step, a first quantization matrix in which a high-frequency component is configured with a value less than 255 is used for quantization. A first selection step of selecting as a quantization matrix;
When it is determined by the processing of the determining step that the quantized value is used for quantization, a second selection of selecting a second quantization matrix included in the information as a quantization matrix used for quantization And a step. In an image processing device that encodes image data,
Acquisition means for acquiring information on encoding performed in the past on the image data,
Orthogonal transformation means for orthogonally transforming the image data,
In quantization, a first quantization matrix used when the information acquired by the acquisition unit is not reused, and a second quantization in which each component has a value equal to or less than the first quantization matrix. Storage means for storing the matrix;
Determining means for determining a quantization value and a quantization matrix used for quantization;
Using the quantization value and the quantization matrix determined by the determination unit, and a quantization unit that performs quantization,
The determining means comprises:
When the information is reused and the quantization value included in the information acquired by the acquisition unit is reusable, a third quantization included in the information acquired by the acquisition unit Decides to use the matrix for quantization,
When the information is reused and the quantization value included in the information is not reusable, it is determined that the second quantization matrix stored in the storage unit is used for quantization. ,
If the information is not reused, the image processing apparatus determines to use the first quantization matrix stored in the storage unit for quantization. In an image processing method of an image processing device that encodes image data,
A first determining step of determining whether to reuse information on encoding performed in the past on the image data;
When it is determined by the processing of the first determination step that the information of the past encoding is not reused, a first quantization matrix for selecting a predetermined first quantization matrix as a quantization matrix used for quantization is used. A selection step;
When it is determined by the processing of the first determination step that the information on the past encoding is reused, it is determined whether a quantization value included in the information is used for quantization. 2 judgment steps;
When it is determined by the processing of the second determination step that the quantization value is not used for quantization, a second quantization matrix in which each component has a value equal to or less than the first quantization matrix is defined as: A second selection step of selecting as a quantization matrix used for quantization;
If it is determined by the processing of the second determination step that the quantization value is used for quantization, a third quantization matrix included in the information is selected as a quantization matrix used for quantization. 3. An image processing method, comprising: A program for causing a computer to execute a process of encoding image data,
A first determining step of determining whether to reuse information on encoding performed in the past on the image data;
When it is determined by the processing of the first determination step that the information of the past encoding is not reused, a first quantization matrix for selecting a predetermined first quantization matrix as a quantization matrix used for quantization is used. A selection step;
When it is determined by the processing of the first determination step that the information on the past encoding is reused, it is determined whether a quantization value included in the information is used for quantization. 2 judgment steps;
When it is determined by the processing of the second determination step that the quantization value is not used for quantization, a second quantization matrix in which each component has a value equal to or less than the first quantization matrix is defined as: A second selection step of selecting as a quantization matrix used for quantization;
If it is determined by the processing of the second determination step that the quantized value is used for quantization, a third quantization matrix included in the information is selected as a quantization matrix used for quantization. 3. A recording medium on which a computer-readable program is recorded. A program for causing a computer to execute a process of encoding image data,
A first determining step of determining whether to reuse information on encoding performed in the past on the image data;
When it is determined by the processing of the first determination step that the information of the past encoding is not reused, a first quantization matrix for selecting a predetermined first quantization matrix as a quantization matrix used for quantization is used. A selection step;
When it is determined by the processing of the first determination step that the information on the past encoding is reused, it is determined whether a quantization value included in the information is used for quantization. 2 judgment steps;
When it is determined by the processing of the second determination step that the quantization value is not used for quantization, a second quantization matrix in which each component has a value equal to or less than the first quantization matrix is defined as: A second selection step of selecting as a quantization matrix used for quantization;
If it is determined by the processing of the second determination step that the quantization value is used for quantization, a third quantization matrix included in the information is selected as a quantization matrix used for quantization. 3. A program comprising: (3) selecting steps. In an information processing apparatus for converting image data,
Decoding means for decoding the supplied image data completely or incompletely;
The image data of the baseband completely decoded by the decoding means, or generated incompletely decoded by the decoding means, the image data encoded to an intermediate stage, up to the intermediate stage, or, Encoding means for completely encoding,
The encoding means,
Acquisition means for acquiring information on encoding performed in the past on the image data,
Orthogonal transformation means for orthogonally transforming the image data,
Storage means for storing a first quantization matrix in which the high-frequency component is configured with a value less than 255;
Determining means for determining a quantization value and a quantization matrix used for quantization;
Using the quantization value and the quantization matrix determined by the determination means, quantization means for performing quantization,
With
The determining unit quantizes a second quantization matrix included in the information obtained by the obtaining unit when the quantized value included in the information obtained by the obtaining unit is reusable. And determining that the first quantization matrix stored in the storage unit is used for quantization when the quantization value included in the information is not reusable. Characteristic information processing device. In an information processing apparatus for converting image data,
Decoding means for decoding the supplied image data completely or incompletely;
Encoding means for encoding the image data completely or incompletely decoded by the decoding means by a method corresponding to a state of decoding by the decoding means,
The encoding means,
Acquisition means for acquiring information on encoding performed in the past on the image data,
Orthogonal transformation means for orthogonally transforming the image data,
In quantization, a first quantization matrix used when the information acquired by the acquisition unit is not reused, and a second quantization in which each component has a value equal to or less than the first quantization matrix. Storage means for storing the matrix;
A determination unit that determines a quantization value and a quantization matrix used for quantization, and a quantization unit that performs quantization using the quantization value and the quantization matrix determined by the determination unit,
The determining means comprises:
When the information is reused and the quantization value included in the information acquired by the acquisition unit is reusable, a third quantization included in the information acquired by the acquisition unit Decides to use the matrix for quantization,
When the information is reused and the quantization value included in the information is not reusable, it is determined that the second quantization matrix stored in the storage unit is used for quantization. ,
If the information is not reused, the information processing apparatus determines to use the first quantization matrix stored in the storage unit for quantization.

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