JP2000197062A - Image coder with encryption function and image decoder with encryption decoding function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image coder that allows a viewer to view a dynamic picture having low image quality, even in if using an image decoder having no capability of decoding encrypted data is used. SOLUTION: A mode discrimination means 102 discriminates whether in-frame coding or inter-frame coding is applied to an input signals that is block-coded. A variable length coder 112 encodes the input signal. When the discrimination result by the mode discrimination means 102 indicates in-frame coding, the coded information is outputted as is, and when the discrimination result by the mode discrimination means 102 indicates inter-frame coding, an encryption device 114 encrypts the coded information and provides an output of the result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to an image encoding device that encrypts a part of code information and an image decoding device that receives and decodes the encrypted code information.

[0002]

2. Description of the Related Art Conventionally, there have been two types of techniques relating to video encryption. A first object is a technique for easily realizing an encryption method having high stability and confidentiality.
A second object is to make it possible to reproduce a low-quality moving image even in an image decoding device having no decryption function.

As a technique developed to achieve the second object, there is a technique disclosed in Japanese Patent Application Laid-Open No. 6-54325. FIG. 5 is a diagram showing a configuration of the above-mentioned conventional technology. This prior art includes image switches 2 and 9, a transformer 3, a quantizer 4, an inverse quantizer 6, an inverse transformer 7, a frame memory 8 with a motion compensation function, a subtractor 12, and an adder 13.
Uses the correlation in the time axis direction together with motion compensation for a moving image, and encodes the moving image using orthogonal transform. Of the output of the quantizer 4, the high-frequency component of the operation result obtained by the orthogonal transform is input to the encryptor 5 and encrypted. On the other hand, the low frequency component and the side information are multiplexed and output together with the encrypted high frequency component without performing encryption.

[0004] Although the quality of the image is degraded by this,
It is possible to reproduce a moving image even in a decryption device without a decryption function.

[0005]

However, in the above prior art, a decoding loop is provided on the image decoding device side.
I needed to hold it. Further, in the image encoding device, since an image frame reproduced from only low-frequency components is used for encoding a next frame, there is a problem that encoding efficiency is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a video decoding apparatus which has a simple configuration, does not reduce the coding efficiency, and has the ability to decode encrypted information. It is an object of the present invention to provide an image encoding device that enables a user to view a program, but also to view a low-quality moving image even in an image decoding device that does not have the ability to decrypt encryption.

Another object of the present invention is to provide an image decoding apparatus for efficiently decoding image data encoded by the image decoding apparatus of the present invention.

[0008]

According to the present invention, there is provided an image coding apparatus having an encryption function for encrypting a part of code information when coding a moving image signal. Encoding means for judging whether the input signal blocked is to be intra-frame encoded or inter-frame encoded, and encoding the input signal based on the judgment result; and If the result of the determination is intra-frame encoding, the code information output from the encoding means is output as it is, and if the result of the determination by the encoding means is inter-frame encoding, Encryption means for encrypting the output code information and outputting the encrypted code information.

According to another aspect of the present invention, there is provided an image encoding apparatus having an encryption function for encrypting a part of code information when encoding a moving image signal. Encoding means for judging whether to block the input signal to be subjected to intra-frame encoding or inter-frame encoding, and encoding the quantized signal by orthogonally transforming the input signal based on the determination result. When the result of the determination by the encoding means is intra-frame encoding, the code information output from the encoding means is output as it is, and when the result of the determination by the encoding means is inter-frame encoding, Is characterized by having encryption means for encrypting and outputting the code information output from the coding means.

[0010] If the image encoding apparatus further includes a multiplexing means for multiplexing the judgment result of the encoding means and the code information output from the selecting means, the decryption which can decrypt the encryption can be performed. In the device, decoding can be performed efficiently.
An image encoding apparatus according to the present invention that achieves the above object is an image encoding apparatus with an encryption function that encrypts a part of code information when encoding a moving image signal, wherein In addition to detecting and encoding a motion vector for each signal, determining whether the input signal is to be intra-frame encoded or inter-frame encoded, and encoding the input signal based on the determination result. Means, encryption means for encrypting the code information of the motion vector output from the encoding means, code information output from the encoding means, and the encrypted motion vector output from the encryption means. And multiplexing means for multiplexing the code information.

If the multiplexing means is configured to multiplex the judgment result of the encoding means together with the code information, a decoding apparatus capable of decrypting a cipher may include:
Decoding can be performed efficiently. The image encoding apparatus of the present invention that achieves the above object is an image decoding apparatus with a decryption function of receiving an image signal in which an inter-frame encoded block is encrypted, decrypting and decrypting the code. Separating means for separating identification information and code information for identifying whether a signal received from an input image signal is an intra-frame encoded signal or an inter-frame encoded signal; and When indicating that it is encoded, decrypting means for decrypting the code applied to the code information and restoring the original code information, and decoding means for decoding the restored code information It is characterized by having.

It is more preferable to have a means for orthogonally transforming the decoded signal after inversely quantizing it. The image encoding apparatus of the present invention that achieves the above object is an image decoding apparatus with a decryption function that receives an image signal in which a motion vector is encrypted, and decrypts and decrypts the encrypted image signal. Separation means for separating code information and an encrypted motion vector from a signal received from the signal, and decryption means for decrypting the encryption applied to the encrypted motion vector and restoring the original motion vector; , Decoding means for decoding the restored motion vector and the code information.

[0013]

Embodiments of the present invention will be described.
First, a first embodiment of an image encoding device with an encryption function according to the present invention will be described. FIG. 1 is a configuration diagram of the first embodiment.

In FIG. 1, reference numeral 101 denotes a differentiator. The differentiator 101 calculates a difference between a block-divided input signal and a block in a previous image frame by motion compensation. 1
02 is a mode determination means. This mode determination means 10
Reference numeral 2 has a function of receiving the input block signal and the output of the differentiator 101 as inputs, and determining whether the input block signal is to be intra-frame encoded or inter-frame encoded. That is, the mode determination means 102 predicts which of the input block and the motion-compensated inter-frame signal will have a smaller number of generated codes for each of the blocked input images, and performs intra-frame coding or frame coding. Select inter-coding. In addition, there is a case where an input image is forcibly encoded in a frame for reasons such as suppressing accumulation of prediction errors or enabling random access of a moving image. Performs intra-frame encoding. Then, the result of the determination is determined by a switch 103, a switch 104, and a switch
5 is output.

Reference numerals 103 and 104 are switches. These switches 103 and 104 are interlocked, and when both of them are connected to the contact a, the correlation in the time axis direction is not used.
It functions as an intra-frame encoding mode for performing intra-frame encoding of the encoding target frame. On the other hand, when connected to the contact b, it functions as an inter-frame encoding mode for encoding the difference from the previous frame. Note that the above-described switching of the contacts is performed based on the determination result of the mode determination unit 102.

Reference numeral 106 denotes a DCT calculator, which is a switch 1
03 is orthogonally transformed by DCT. Reference numeral 107 denotes a quantizer 107, which quantizes the result of the orthogonal transformation.
108 is an inverse quantizer, and 109 is an inverse DCT calculator.
The inverse quantizer 108 and the inverse DCT operator 109 perform inverse quantization and inverse DCT operation on the output of the quantizer 107, respectively. The output is used to generate a local decoded signal through an adder 110 and stored in a frame memory 111.

Reference numeral 105 denotes a motion compensation processing unit. The motion compensation processing unit 105 refers to image data within the motion compensation range among the input block image and the contents of the frame memory 111, and detects an optimal motion vector in the input block. The previous frame data compensated by the detected motion vector is output to the differentiator 101. 11
Reference numeral 2 denotes a variable length encoder, which encodes the output of the quantizer 107 into a variable length code.

Reference numeral 113 denotes a variable length encoder, which encodes a motion vector into a variable length code. Reference numeral 114 denotes an encryptor. The encryptor 114 encrypts the output of the variable length encoder 112. 115 is a switch. In the switch 115, the output of the variable length encoder 112 is input to a contact a, and the output of the encryptor 114 is input to a contact b.
The switching of the contacts is performed based on the result of the determination by the mode determining means 102. That is, if the result of the determination is the intra-frame encoding mode, the output is switched to the contact point a to select the output of the variable-length encoder 112 that is not encrypted, and if the result of the determination is the inter-frame encoding mode, Switching to the contact point b, the output of the variable length encoder 112 encrypted by the encryptor 114 is selected.

Reference numeral 116 denotes a multiplexer. This multiplexer 1
Reference numeral 16 multiplexes and outputs the determination results of the switch 113, the variable length encoder 115, and the mode determination means 102. In the first embodiment, looking at the configuration in FIG. 1, it is a general motion-compensated interframe encoder except for the encryptor 114 and the switch 115. That is, when the result of the determination by the mode determining means 102 is the inter-frame encoding mode, only the image data inter-frame encoded by the encryptor 114 is encrypted.

Next, the operation of the first embodiment will be described. The switch 115 controls the contacts according to a mode designating signal output from the mode determiner 102, that is, a mode signal designating intra-frame coding or inter-frame coding. When the intra-frame encoding is performed, the output of the variable length encoder 112 is output to the multiplexer 116 as it is.

In this case, the image can be normally decoded even by an image decoding apparatus having no decryption function. On the other hand, when the inter-frame encoding is specified, the switch 115 outputs the result of encrypting the output of the variable length encoder 112, that is, the output of the encryptor 114, to the multiplexer 116. As a result, an image decoder having no decryption function cannot normally decode the corresponding input image block.

Although it depends on the implementation of the image decoder, a block that receives a variable-length code that cannot be decoded is generally determined to be an error and is replaced by a block at the same position in the previous image frame. A block corresponding to the block of the reproduced moving image is not normally displayed until the next block is intra-coded. As described above, in encoding moving image data, all screens are intra-frame encoded at least at a predetermined cycle. Therefore, even in an image decoding apparatus having no decryption function, low quality It is possible to watch a moving image program.

Next, an embodiment of an image decoding apparatus for normally decoding image information encoded by the image encoding apparatus according to the first embodiment will be described. FIG. 2 is a block diagram of an image decoding apparatus for normally decoding image information encoded by the image encoding apparatus of FIG. FIG.
Reference numeral 201 denotes a separation unit. The separation unit 201 separates a mode designation signal, an image code, and a motion vector from the received bit string.

204 is a variable length decoder, 205 is an inverse quantizer, 206 is an inverse DCT operator, 207 is an adder, 20
Reference numeral 8 denotes a switch, and 211 denotes a variable-length decoder, which has the same function as the corresponding part of the image encoder shown in FIG. Reference numeral 209 denotes a motion vector processing unit. The motion vector processing unit 209 receives a motion vector from the separation unit 201, reads a block indicated by the motion vector from the previous frame stored in the frame memory 210, and outputs the block to the adder 207. With the switch 208,
In the case of intra-frame encoding, the previous frame data is not output to the adder 207. The played video frame is
It is output and stored in the frame memory 210.

The above configuration is that of a general image decoder. However, the image decoder of FIG. 2 further includes a decryptor 202 and a switch 203. The decryptor 202 has a function of restoring the information encrypted by the encryptor 114 of the image encoder of FIG. 1 to original data. The switch 203 is contact-controlled by a mode designation signal output from the separation unit 201, and switches between execution of decryption and stop. That is, when the mode designation signal is the intra-frame coding mode, the output is switched to the contact a to select the output of the unencrypted separating unit 201, and when the mode designation signal is the inter-frame coding mode, the contact b, and selects the data decrypted by the decryption device 202.

In the operation of the image encoder of FIG. 1, the image decoding apparatus performs inter-frame coding in response to the fact that encryption is performed only on blocks to be inter-coded. Only the code data portion of the block is decrypted. A second embodiment of the image encoding device according to the present invention will be described. FIG. 3 is a configuration diagram showing the configuration of the third embodiment.

In FIG. 3, 301 is a differentiator, 302 is mode determining means, 303 and 304 are switches, 305 is a motion compensation processing unit, 306 is a DCT calculator, 307 is a quantizer, 308 is an inverse quantizer, 309 is an inverse DCT calculator, 3
10 is an adder, 311 is a frame memory, 312 and 3
13 is a variable length encoder. These components are the same as the components of the image encoding device shown in FIG. 1 described above, and thus detailed description will be omitted.

The difference between the second embodiment and the first embodiment is that the motion vector is encrypted. As a result, the encryptor 314 is changed to the variable-length encoder 313.
, And the output of the variable-length encoder 313 is encrypted by the encryptor 314. Therefore, a switch corresponding to the switch 103 in FIG. 1 is not required in the present embodiment.

Next, the operation of the second embodiment will be described. The contacts of the switches 303 and 304 are controlled by a mode designating signal output by the mode determining unit 302, that is, a mode signal designating intra-frame coding or inter-frame coding. When the intra-frame encoding is performed, the output of the variable length encoder 312 is output to the multiplexer 315 as it is.

In this case, the image can be normally decoded even by an image decoding apparatus having no decryption function. On the other hand, when the inter-frame coding is specified, the output of the encryptor 314 is output to the multiplexer 315. As a result, an image decoder having no decryption function cannot normally decode the corresponding input image block. Although it depends on the implementation of the image decoder, a block that receives a variable-length code that cannot be decoded is generally determined to be an error and is replaced with a block at the same position in the previous image frame. The block corresponding to the block of the reproduced moving image is the next block until this block is intra-coded.
It is not displayed properly. As described above, in encoding moving image data, all screens are intra-frame encoded at least at a predetermined cycle. Therefore, even in an image decoding apparatus having no decryption function, low quality It is possible to watch a moving image program.

Next, an image decoding apparatus corresponding to the image encoding apparatus according to the second embodiment will be described. FIG. 4 is a configuration diagram showing a configuration of the image decoding apparatus according to the present embodiment. In FIG. 4, reference numeral 401 denotes a separation unit. This separation unit 40
1 separates a mode designation signal, an image code, and a motion vector from the received bit string.

403 is a variable length decoder, 404 is an inverse quantizer, 405 is an inverse DCT operator, 406 is an adder, 40
Reference numeral 7 denotes a switch, and reference numeral 410 denotes a variable-length decoder, which has the same function as the corresponding part of the image encoder shown in FIG. The above configuration is that of a general image decoder. However, the image decryptor of FIG. 4 has a decryption device 402 in addition to these components. This decryptor 402
Receives the encrypted motion vector separated by the separation unit 401 and decrypts the encrypted motion vector.

Reference numeral 408 denotes a motion vector processing unit.
The motion vector processing unit 408 includes the variable length decoder 41
A motion vector is input from 0, a block indicated by the motion vector is read from the previous frame stored in the frame memory 409, and output to the adder 406. The switch 407 does not output the previous frame data to the adder 406 in the case of intra-frame encoding. The reproduced moving image frame is output and stored in the frame memory 409.

The image decoding apparatus decrypts only the motion vector in response to the fact that only the motion vector is encrypted in the operation of the image encoder of FIG.

[0035]

According to the image encoding apparatus of the present invention, even if the image decoding apparatus does not have a decryption function, it is possible to view a moving image program with low quality. This effect can be used for publications and advertisements. This is because no encryption is performed on intra-coded blocks,
The above effects can be obtained. In addition, since the intra-frame encoding always occurs within a certain period, the above-described effect can be obtained.

Further, according to the present invention, the present invention can be easily applied to a moving picture coding method which is currently widely used. This is because the present invention is applied to only a part of the video coding system, and does not affect the grammatical structure, the multiplexing system, the audio coding, and the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment according to an image encoding device of the present invention.

FIG. 2 is a configuration diagram of a first embodiment according to an image decoding device of the present invention.

FIG. 3 is a configuration diagram of a second embodiment according to the image encoding device of the present invention.

FIG. 4 is a configuration diagram of an image decoding apparatus according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional image decoding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Difference machine 102 Mode determination means 103, 104 Switch 105 Motion compensation processing part 106 DCT operator 107 Quantizer 108 Inverse quantizer 109 Inverse DCT operator 110 Adder 111 Frame memory 112 Variable length encoder 113 Variable length code 114 114 Encryptor 115 Switch 116 Multiplexer

Claims (8)

[Claims] An image coding apparatus with an encryption function for encrypting a part of code information when coding a moving image signal, comprising: Encoding means for judging whether to perform inter-frame encoding, and encoding the input signal based on the judgment result; and when the judgment result of the encoding means is intra-frame encoding, the encoding means Encrypting means for outputting the output code information as it is, and encrypting and outputting the code information output from the coding means when the result of the determination by the coding means is inter-frame coding; An image encoding device with an encryption function, characterized by the following. 2. An image coding apparatus with an encryption function for encrypting a part of code information when coding a moving image signal, wherein an intra-frame coding of a blocked input signal is performed. Encoding means for judging whether to perform inter-frame encoding, and encoding a signal obtained by orthogonally transforming and quantizing the input signal based on the judgment result; and a decision result of the encoding means being intra-frame encoding. If, the code information output from the encoding means is output as it is, and if the result of the determination by the encoding means is inter-frame encoding, the code information output from the encoding means is encrypted. An image encoding apparatus with an encryption function, comprising: an encryption unit that outputs an encrypted image. 3. The encryption device according to claim 1, further comprising a multiplexing unit that multiplexes a result of the determination by the encoding unit and code information output from the selection unit. Image encoding device with function. 4. An image coding apparatus with an encryption function for encrypting a part of code information when coding a moving image signal, comprising detecting a motion vector for each block-input signal. Along with encoding, the input signal is encoded in a frame, or it is determined whether to perform inter-frame encoding, encoding means for encoding the input signal based on the determination result, output from the encoding means Encrypting means for encrypting the encoded motion vector code information; multiplexing the code information output from the encoding means and the encoded motion vector code information output from the encrypting means. An image encoding device with an encryption function, comprising: 5. The apparatus according to claim 4, wherein the multiplexing unit multiplexes the determination result of the encoding unit together with code information. 6. An image decoding apparatus with a decryption function for receiving an image signal in which an inter-coded block is encrypted, and decrypting and decrypting the code, wherein the image signal is received from an input image signal. Separation means for separating identification information and code information for identifying whether a signal is intra-frame encoded or inter-frame encoded, and that the identification information is inter-frame encoded In the case shown, the decryption means comprises: decryption means for decrypting the code applied to the code information and restoring the original code information; and decryption means for decoding the restored code information. Image decoding device with function. 7. The image decoding apparatus according to claim 6, further comprising means for performing an orthogonal transform after dequantizing the decoded signal. 8. An image decoding apparatus having a decryption function for receiving an image signal in which a motion vector is encrypted, and decrypting and decrypting the code, wherein code information and code information are obtained from a signal received from the input image signal. Separating means for separating the encrypted motion vector from the encrypted motion vector; decrypting means for decrypting the encryption applied to the encrypted motion vector to restore the original motion vector; and An image decoding apparatus with a decryption function, comprising: decoding means for decoding code information.