JPH09172633A - Editing device and decoding device of picture compressing code string - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient picture processing effect and to obtain the editing device and the decoding device of a picture compressing code string without usage limitation by providing a compressing code string replacing device, etc. SOLUTION: The decoding device 1 decodes the compressing code string of moving image which is inputted from outside, adopts it as a reproduction picture and outputs it to a picture processing designating means 2. The picture processing designating means 2 displays the reproduction pictures, designates the optional picture required to be executed a picture processing such as a mosaic processing and a scramble processing, etc., from them by GOP unit and picture unit, etc., and also designates which encoding parameter is rewritten. An encoding parameter retrieving device 3 detects address information in the compressing code string of the designated encoding parameter and a time information detecting device 4 and a space information detecting device 5 detect designated information and transmit them to the compressing code string reproacing device 6. The compressing code string replacing device 6 specifies the encoding parameter to be rewriting object in the compressing code sting based on respective kinds of information from the respective devices and rewrites(replace) it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to MPEG1 and M
An image compression code string editing apparatus for performing image processing such as mosaic processing and scramble processing on image data compressed and coded according to the PEG2 system, and decoding for decoding the image compression code string obtained by this editing apparatus. Regarding the device.

[0002]

2. Description of the Related Art In recent years, with the development of moving picture compression coding technology based on the MPEG1 and MPEG2 systems, there is an increasing demand for image concealment such as mosaic processing or scramble processing for this moving picture compression code sequence.

Conventionally, as a method of performing such image processing of a compression code string of a moving image, a first method of changing a value of a quantization table at the time of compression encoding of a moving image (Japanese Patent Laid-Open No. 6-
22212), and a second method of rewriting the quantization parameter when decoding the compressed code string (Japanese Patent Laid-Open No. 107455/1995)
No.), and a third method of rewriting the DCT type (frame DCT, field DCT) for each macroblock (JP-A-7-111647, etc.). Each of the above methods does not require any modification to the original image itself, and thus has the advantage of excellent efficiency.

However, in the method of changing the value of the quantization table at the time of encoding or decoding like the first and second methods, it is difficult to predict what kind of reproduced image is actually obtained. Therefore, depending on the original image, the desired concealment effect may not be sufficiently obtained. Therefore, in the first method of performing special effect processing simultaneously with encoding, the encoded data is input to the decoding device to check the reproduced image, and the value of the quantization table is changed again and re-encoded if necessary. Need to be converted.

On the other hand, in the third method of rewriting the DCT type for each macroblock, a stable scrambling effect can be obtained.

By the way, in MPEG, images are handled in units of pictures, and in MPEG2, frames and fields can be assigned to the pictures. In the case of a frame-structured picture, the DCT is a macroblock unit and a frame DCT mode and a field D.
It can be switched by switching to the CT mode. That is, in the third method, the mosaic effect is realized by rewriting the coding parameter to the field DCT mode in the frame DCT mode and to the frame DCT mode in the field DCT mode.

However, when the picture has a field structure, the type of DCT is only the field DCT mode. Therefore, the third method cannot perform image processing on a picture having a field structure.
There is a problem that applications are limited.

[0008]

Conventionally, when image processing such as mosaic processing or scramble processing is performed on a compressed code string of a moving image, the value of a quantization table is changed at the time of encoding or decoding, Although a method of rewriting the DCT type for each macroblock has been adopted, a method of changing the value of the quantization table at the time of encoding or decoding does not guarantee a sufficient image processing effect and D for each macroblock is not guaranteed.
The method of rewriting the CT type has a problem that the application is limited to a picture or frame structure.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an image compression code sequence editing apparatus and a decoding apparatus which can obtain a sufficient image processing effect and have no application restrictions.

[0010]

In order to achieve the above-mentioned object, an image compression code string editing apparatus of the present invention is arranged such that an arbitrary image in an image compressed and coded in accordance with the MPEG system is macroblock unit. The image designating means to be designated and the QSC (Quantizer Scale Co) in the coding parameters included in the compression code string of the macroblock designated by the image designating means.
de) is replaced with a predetermined value and a coding parameter replacing means is provided.

The QSC is a value indicating the quantization step size when quantizing the DCT coefficient, and is defined for each macroblock into which the picture is subdivided. By replacing this QSC with a predetermined value, a mosaic-like special effect can be applied to the designated macroblock of the compression code string. Further, since the degree of blurring of the mosaic tone can be varied depending on the value of QSC, setting the value after replacement of QSC to a small value guarantees a sufficient image concealment effect.

Further, the image compression code sequence editing apparatus of the present invention is designated by the image designation means for designating an arbitrary image in the image compression-coded according to the MPEG system in GOP units, and by the image designation means. PCT (Picture Coding Type) in the encoding parameters included in the compressed code sequence of the GOP
And a coding parameter replacing means for replacing the PCT indicating the I picture with a predetermined value.

The PCT is an encoding parameter of the picture layer in the data structure of the MPEG2 system, and for each picture, its type is an I picture, a P picture, or a B picture forming a GOP (Group of Pictures). This is the code shown. By rewriting the PCT indicating the Ι picture in this PCT to a predetermined value indicating the P picture or Β picture, all the picture images in the GOP become undecodable, and scrambling processing can be performed efficiently in GOP units. It will be possible.

Further, the image compression code sequence editing apparatus of the present invention comprises an image designation means for designating, in picture units, an arbitrary image in the images compression-coded according to the MPEG system.
And a coding parameter replacing unit that replaces AS (Alternate Scan) in the coding parameters included in the compression code string of the picture specified by the specifying unit with another value.

AS is a coding parameter of the picture layer in the data structure of the MPEG2 system, and is a flag that defines for each picture whether the DCT coefficient scanning method is zigzag scanning or alternate scanning. Therefore, by rewriting this AS, effective scrambling processing can be performed in picture units.

Further, the image compression code string editing apparatus of the present invention is further provided with means for adding the identification information of the replaced coding parameter to the image compression code string including the replaced coding parameter.

An image compression code sequence decoding apparatus according to a sixth aspect of the present invention decodes an image compression code sequence including the identification information of the replacement encoding parameter, and identifies from the input image compression code sequence. The information is separated, and the replacement coding parameter in the image compression code string is determined based on this identification information and restored to the value before replacement.

Further, the image compression code sequence editing apparatus of the present invention encodes the replaced encoding parameter address information and the restoration information for restoring the encoding parameter to the value before the substitution. It further comprises means for adding to the image compression code sequence including the parameters.

According to a seventh aspect of the present invention, a decoding apparatus for an image compression code string is for decoding an image compression code string including the address information and the restoration information of the above replacement coding parameter, and the input image compression code is used. The address information and the restoration information are separated from the code string, the replacement coding parameter in the image compression code string is determined based on the address information, and the replacement coding parameter is restored to the value before replacement using the restoration information.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the arrangement of a moving picture compression code string editing apparatus according to this embodiment. As shown in the figure, this compression code string editing apparatus includes a decoding apparatus 1, an image processing designation means (user interface) 2, an encoding parameter retrieval apparatus 3, a temporal information detection apparatus 4, a spatial information detection apparatus 5, and compression. It is composed of a code string replacing device 6.

The decoding device 1 decodes a compression code string of a moving image input from the outside to obtain a reproduced image, and outputs it to the image processing designating means 2. The image processing designating means 2 displays the reproduced image input from the decoding device 1, and GO among the arbitrary images to be subjected to image processing such as mosaic processing and scramble processing is GO.
It is specified in units of P, in units of pictures, or in units of macroblocks in a picture, and the QSC (Quantizer) in the encoding parameters included in the compression code string of these target images
Scale Code), PCT (Picture Coding Type), AS
Specify which of (Alternate Scan) to rewrite according to the request from the operator. The macroblock in the picture is designated by, for example, enclosing an area to be subjected to image processing in the reproduced image with a mouse or the like.

The coding parameter search device 3 detects the address information in the compression code string of the coding parameter designated by the image processing designating means 2 to detect the compression code string replacing device 6.
Send to The time information detection device 4 detects the TC (Time Code) of the image (GOP) designated by the image processing designation means 2 as the image processing time information, and the compression code string replacement device 6
Send to When the image is designated in macroblock units within a picture, the spatial information detection device 5 detects the spatial information of the macroblock and sends it to the compression code string replacement device 6.

When an image is designated in GOP units or picture units (in the case of scramble processing, etc.), the compression code string replacing device 6 receives information (encoding) from the coding parameter searching device 3 and the time information detecting device 4. Based on the address information of the parameter and the image processing time information), the coding parameter to be rewritten in the compression code string is specified and rewritten (replaced). In addition, the compression code string replacement device 6 uses the coding parameter search device 3, the temporal information detection device 4, and the spatial information detection device 5 when an image is designated in units of macroblocks in a picture (for mosaic processing, for example). On the basis of each information (encoding parameter address information, image processing time information, image processing space information), the coding parameter to be rewritten in the compression code string is specified and rewritten (replaced).

The operator selects Q in the image processing designation means 2.
It is possible to select which of the coding parameters of SC, PCT and AS should be rewritten.

QSC (Quantizer Scale Code) is DC
It is a value indicating the quantization step size when quantizing the T coefficient. This QSC is an encoding parameter of the macroblock layer in the data structure of the MPEG2 system, and is defined for each macroblock obtained by subdividing the picture. By rewriting this QSC, a mosaic-like special effect can be applied to the designated macroblock of the compression code string.

PCT (Picture Coding Type) is MPE
It is an encoding parameter of the picture layer in the data structure of the G2 system, and its type is GOP (Group
of Pictures) is a code indicating whether it is a Ι picture, a P picture, or a Β picture. In the present embodiment, when an image is designated by the image processing designation means 2 in GOP units, the compression code string replacement device 6 rewrites the PCT indicating the I picture in the GOP with a value indicating the P picture or the B picture. Usually, one GOP has one or more I pictures, a P picture is an encoded difference from an I picture, and a B picture is an encoded difference from an I picture or a P picture. The decoding device identifies each picture type by the PCT of the picture layer in the compression code string, first decodes the I picture, and then decodes the P or B picture. Therefore, I
If the picture does not exist, all the picture images in the GOP cannot be decoded.
If is replaced with a value indicating a P picture or a B picture, scrambling can be performed in GOP units.

AS (Alternate Scan) is an encoding parameter of the picture layer in the data structure of the MPEG2 system, and a flag that defines for each picture whether the scanning method of the DCT coefficient is zigzag scanning or alternate scanning. Is. Therefore, by rewriting this AS, scrambling can be performed in picture units.

FIG. 2 shows the configuration of the compression code string replacing device 6. In the figure, reference numeral 11 is an address counter that obtains the address of the compression code string currently being input by incrementing it by 1 each time one byte of the compression code string is input. 1
Reference numeral 2 is an encoding parameter retrieval device 3 and time information detection device 4.
And an address detection device that determines the address of the coding parameter to be rewritten based on each information from the spatial information detection device 5. The comparator 13 compares the value of the address output from the address counter 11 with the value of the address determined by the address detection device 12. When the address values match, the comparator 13 sends a control signal to the selector 14. Upon receiving the control signal from the comparator 13, the selector 14 outputs the addition value determined for each encoding parameter of QSC, PCT, AS to the adder 15, and otherwise outputs “0” to the adder 15. To do. Here, the added value is set to a value that brings about a desired image processing effect with respect to the coding parameter for rewriting. The adder 15 adds the selector 1 to the corresponding coding parameter in the input compression code string.
The output addition value of 4 is added and output as a compressed code string subjected to image processing. As described above, a compression code string that has been subjected to mosaic processing or scramble processing can be obtained.

In order to obtain a normal reproduced image from which the image processing has been solved from the above compression code string of the moving image, a code string for restoring the rewritten coding parameter (hereinafter referred to as an encryption key). ) Must be added to the compressed code string after image processing.

FIG. 3 is a diagram showing the configuration of the compression code string replacing device 6 having such an encryption key adding function. As shown in the figure, the compression code sequence replacing device 6 is configured by adding an encryption key generating device 16 and a code sequence synthesizing device 17 to the configuration of the compression code sequence replacing device shown in FIG. Encryption key generation device 16
Generates a code string including the address information of the rewritten code parameter output from the address detecting device 12 and the added value input to the selector 14 as an encryption key and sends it to the code string synthesizing device 17. The code string synthesizing unit 17 synthesizes this encryption key with the image-processed compression code string output from the adder 15, and outputs the compression code string with the encryption key.

FIG. 4 is a diagram showing the structure of a decoding device for decoding a compression code string with an encryption key. In the figure, an encryption key separating device 21 inputs a compression code string with an encryption key, separates it into an encryption key and other compression code strings, and outputs the encryption key to an address / addition value separating device 22, The compressed code string is output to the address counter 23 and the subtractor 24, respectively. The address / addition value separation device 22 separates the input encryption key into address information of the code parameter and the addition value, outputs the address information to the comparator 25, and outputs the addition value to the selector 26. The comparator 25 compares the address information of the code parameter with the current address value of the compressed code string output from the address counter 23, and when they match, outputs a control signal to the selector 26. The selector 26 receives the control signal from the comparator 25 and receives the address / addition value separation device 22.
The addition value from is selected and sent to the subtractor 24, and otherwise, "0" is output to the subtractor 24. The subtractor 24 subtracts the output addition value of the selector 26 from the corresponding encoding parameter in the compression code string input from the encryption key separating device 21,
The coding parameter is returned to the original state before the rewriting and sent to the decoding device 27. As a result, a reproduced image whose image processing has been canceled can be obtained.

Thus, according to the moving picture compression code string editing apparatus of the present embodiment, QSC, PCT, and A in the compression code string are used.
By rewriting any of the coding parameters of S, it is possible to perform reliable mosaic processing and scramble processing on the moving image compression code sequence without any restrictions such as the frame / field structure of the picture.

Further, in this embodiment, since the degree of blurring of the mosaic tone can be changed by the value of QSC,
By setting a small value after QSC replacement, a sufficient image concealing effect is guaranteed.

Further, according to the method of replacing QSC and PCT of this embodiment, the value added to QSC and PCT is required as an encryption key at the time of image processing in order to restore QSC and PCT to the original values. As compared with the conventional method in which the DCT type is rewritten between the frame DCT mode and the field DCT mode, that is, only the value of the flag is inverted, the risk of illegally canceling the image processing can be greatly reduced. .

Furthermore, according to the present embodiment, scrambling can be easily performed in GOP units simply by replacing the PCT indicating the I picture with the value indicating the P picture or the B picture.

Further, according to this embodiment, QSC, P
By selecting an encoding parameter to be rewritten in CT or AS, image processing can be performed in various units of GOP units, picture units, or macroblock units in a picture, and a device with excellent editing efficiency can be provided. Can be realized.

[0038]

As described above, according to the image compression code sequence editing apparatus of the present invention, by replacing QSC with a predetermined value, a special effect of a mosaic tone is obtained for a designated macro block of the compression code sequence. QSC
Since the degree of blurring of the mosaic tone can be changed by the value of, a sufficient image concealment effect is guaranteed by setting the value after QSC replacement to be small.

Further, according to the image compression code string editing apparatus of the present invention, the PCT indicating the I picture in the PCT is set to P
By rewriting to a predetermined value indicating a picture or a B picture, all the picture images in the GOP cannot be decoded, and scramble processing can be efficiently performed in GOP units.

Further, according to the image compression code string editing apparatus of the present invention, effective scrambling processing can be performed in picture units by rewriting AS.

Therefore, according to the present invention, a sufficient image processing effect can be obtained, and an editing device and a decoding device for an image compression code sequence without application restrictions can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a moving image compression code string editing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a compression code string replacement device in FIG.

FIG. 3 is a block diagram showing a configuration of a compression code string replacement device having an encryption key addition function according to the present invention.

FIG. 4 is a block diagram showing a configuration of a decoding device for decoding a compression code string with an encryption key according to the present invention.

[Explanation of symbols]

 1 ... Decoding device 2 ... Image processing designation means 3 ... Encoding parameter retrieval device 4 ... Temporal information detection device 5 ... Spatial information detection device 6 ... Compressed code sequence replacement device 11 ... ... Address counter 12 ... Address detection device 13 ... Comparator 14 ... Selector 15 ... Adder 16 ... Cryptographic key generation device 17 ... Code string synthesis device 21 ... Cryptographic key separation device 22 ... Address and addition Value separation device 23 ... Address counter 24 ... Subtractor 25 ... Comparator 26 ... Selector 27 ... Decoding device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiko Yamauchi 3-3-9 Shimbashi, Minato-ku, Tokyo Inside Toshiba Abu E Co., Ltd.

Claims (7)

[Claims] 1. An image specifying unit for specifying an arbitrary image in an image compressed and coded according to the MPEG system in macroblock units, and a compression code string of the macroblock specified by the image specifying unit. QSC (Quan in encoding parameter
An image compression code string editing apparatus, comprising: an encoding parameter replacing unit that replaces tizer Scale Code) with a predetermined value. 2. An image designation unit for designating, in GOP units, an arbitrary image in an image compression-encoded according to the MPEG system, and an encoding included in a compression code string of the GOP designated by the image designation unit. PCT (Picture Codi in the parameters
ng Type), a coding parameter substituting means for substituting a PCT indicating an I picture with a predetermined value. 3. An image designating unit for designating, in picture units, an arbitrary image in an image compressed and coded according to the MPEG system, and a coding parameter included in a compression code string of a picture designated by the designating unit. Inside AS (Alternate Scan)
And an encoding parameter substituting means for substituting the value with another value. 4. The image compression code string editing apparatus according to claim 1, wherein the identification information of the replaced coding parameter is added to the image compression code string including the replaced coding parameter. An image compression code string editing apparatus, further comprising means. 5. The image compression code string editing device according to claim 4, wherein the identification information of the replaced encoding parameter is the address information of the replaced encoding parameter, and the value before replacing the encoding parameter. An image compression code string editing apparatus, comprising: restoration information for restoring the image compression code sequence. 6. A decoding device for decoding an image compression code string including identification information of the replacement coding parameter obtained by the image compression code string editing device according to claim 4, wherein the image compression code string includes the identification information. Separating means for separating, and based on the identification information separated by the separating means, a coding parameter restoring means for judging the replacement coding parameter in the image compression code string and restoring the value before replacement An apparatus for decoding an image compression code sequence, comprising: 7. The image compression code sequence decoding apparatus according to claim 6, wherein the replacement coding parameter identification information is the replacement coding parameter address information, and the coding parameter is a value before replacement. A decoding device for an image compression coded stream, which includes restoration information for restoration.