JP3834364B2 - Image information transmission or recording method, apparatus and system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for transmitting / recording and reproducing image information in an image communication / broadcasting / database system.
[0002]
[Prior art]
Due to advances in electronic device technology and the like, video and audio are generally digitized and transmitted and stored. Since information such as video and audio has a very large amount of information as it is as the original information, it is often transmitted or stored as an encoded bit stream after being compressed (encoded) using an information compression technique. At this time, in order to correctly perform image reproduction, it is necessary to employ a common image encoding method on the encoding side and the reproduction side. For this reason, H.264 is an international standard for image coding. Systems such as H.261, MPEG1, and MPEG2 have already been determined.
[0003]
MPEG4 is one of the image coding methods currently being standardized. In this system, it has been studied to incorporate new functions that were not available in the conventional standard encoding system. One of these is content-based coding. This is a technique aimed at facilitating processing such as image editing and composition by independently encoding objects in an image. 1 and 2 show examples of terminals that perform content-based coding processing. Parts indicated by common numbers indicate the same thing. First, in the transmission / recording terminal 101 of FIG. 1, the region dividing unit 103 performs region division processing on the input original image signal 102. For example, assuming that an image including two people and a background is given as an input, the region dividing unit has three signals, namely, a signal 104 of a portion in which the background is reflected and signals 105 and 106 of portions in which two persons are respectively photographed. Images are divided into In addition, there is a method in which necessary portions are separately fetched from a plurality of images instead of performing region division on one input image. Encoding units 107, 108, and 109 perform encoding processing on the region-divided signals, and output encoded bit streams 110, 111, and 112. Of course, regarding this processing, instead of having a plurality of encoding processing units, one encoding processing unit may separately encode three parts (in this case, the encoding processing unit performs the three-time encoding process). Will do). The encoded bit stream is multiplexed by the multiplexing unit 113 and output as one encoded bit stream 114 to the communication path or storage device.
[0004]
In the receiving / reading terminal 201 of FIG. 2, the encoded bit stream 114 received from the communication path or read from the storage device is divided into encoded bit streams 110, 111, and 112 of each part by the data dividing unit 202. . These bit streams are decoded by the decoding units 203, 204, and 205, respectively, and image signals 104, 105, and 106 representing the respective parts are obtained. These image signals are synthesized again as one image by the image signal synthesis unit 206, and a reproduced image signal 207 is output.
[0005]
In FIGS. 1 and 2, an example of reproducing an image signal input on the transmission / recording side as it is on the reception / reading side was taken up, but Content-based coding was originally devised for the purpose of using such a method. It is not a thing. In Content-based coding, objects in an image are encoded separately, so editing processing that deletes, adds, enlarges, reduces, or deforms specific objects can be performed on the encoded bitstream . On the other hand, the conventional encoding method is H.264. In H.261, MPEG1, and MPEG2, encoding is performed in units of small blocks in an image, and generally, the boundary lines of the small blocks do not coincide with the contour of an object in the image. For this reason, in order to perform the above-described editing process, the encoded image information must be once decoded into an analog signal.
[0006]
[Problems to be solved by the invention]
If the encoded image information is encrypted, the entire range of the image cannot be viewed unless there is a key for decryption.
[0007]
[Means for Solving the Problems]
The image is encoded by content-based coding, and encryption processing is performed only on information about a specific object. When reproducing information encoded by this method, a part of the image can be viewed even if there is no key for decryption. Further, by switching the object to be encrypted, the encryption process can be effectively performed without increasing the processing amount (= terminal complexity).
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In pay broadcasting such as analog TV broadcasting and CATV, a method called line rotation is often used to encrypt TV signals. This is a method of scrambling the image signal within the same line (scanning line) (changing the order of signals to make the contents unknown). The paying user (subscriber) has the key to unscramble this, so that the correct image can be reproduced. On the other hand, a recipient (non-subscriber) who has not paid a fee cannot view the correct image because he / she cannot scramble. However, if there is a restriction on the severity of the scramble (for example, a restriction on the displacement of the signal position before and after the scramble), even if the scramble is applied, a small amount of information can be obtained from the reproduced image. Can do. This “slight information” is said to have the effect of generating the willingness to join non-subscribers.
[0009]
On the other hand, when the digitized image information is encrypted and transmitted, a method of encrypting and transmitting the encoded bit stream can be considered. In this case, however, a recipient who does not normally have a key for decryption cannot see the image information contained in the received encoded bitstream. This is because the bit stream that has not been decrypted is completely meaningless information for the decryption device of the receiving terminal. In order to prevent this, a method of encoding and transmitting a scrambled image signal can be considered. However, in this method, since the statistical properties of the image signal after being scrambled are greatly changed from those of a normal image signal, there arises a problem that the information compression rate in encoding is lowered.
[0010]
FIG. 3 shows an example of a transmission / recording apparatus 301 that performs encoding and encryption processing by the method of the present invention. The parts indicated by the common numbers in FIG. 1 indicate the same parts. The region dividing unit 103 performs region division processing on the input original image signal 102. As in the case of FIG. 1, assuming that an image including two persons and a background is given as an input, the image is divided into three parts 104 and 105 in which the background 106 and two persons are captured. Let's say. Encoding units 107, 108, and 109 perform encoding processing on each of the divided signals, and encoded bit streams 110, 111, and 112 are output. The encoded bitstreams 110 and 111 are supplied to the multiplexing unit 304 as they are in the case of FIG. 1, but the encoded bitstream 112 containing the information about the person B is stored in the encryption unit 302 with the encryption key 306. After being used and encrypted, the encrypted bit stream 303 is supplied to the multiplexing unit. At this time, the encoded bitstreams 110, 111, and 112 each include information for identifying whether the encoded bitstream is an encrypted bitstream, and this information is used during reproduction. The multiplexed bit stream 305 is output to a communication path or a storage device.
[0011]
FIG. 4 shows a configuration example of the receiving / reading apparatus 401 for the bit stream transmitted or recorded by the apparatus of FIG. Portions denoted by numbers common to FIGS. 1, 2, and 3 indicate the same components. After the multiplexed bit stream 305 is received or read, the data dividing unit 402 divides the data into three bit streams 110, 111, and 303. Each encoded bit stream incorporates identification information indicating whether or not the bit stream is encrypted. Therefore, this apparatus supplies the encoded bit streams 110 and 111 to the decoding units 203 and 204 as they are, while supplying the encrypted encoded bit stream 303 to the descrambling unit 403, where the encryption is performed. The encryption is released using the key 404. The key 404 for decrypting and the encryption key (306 in FIG. 3) may be the same or different depending on the encryption method employed. The encoded bit stream 112 that is the output of the descrambling unit is supplied to the decoder 205. The image signals 104, 105, and 106 that are the outputs of the three decoders are combined in the image signal combining unit 206 to obtain a reproduced image signal 207.
[0012]
The above is the processing when the playback side has key information for decrypting the encryption. On the other hand, if the playback side does not have this key, the cipher cannot be correctly decrypted. Therefore, the image signal 106 relating to the person B in FIG. 4 cannot be correctly reproduced. However, since the signal 104 related to the background and the signal 105 related to the person A can be correctly reproduced, in the finally obtained output image, other than the person B is correctly reproduced. For this reason, the user can obtain limited information from an incompletely reproduced image even though the user does not have a key.
[0013]
The transmitting / recording device and the receiving / reading device described with reference to FIGS. 3 and 4 can be used as components of a communication / broadcasting system and a database (video on demand) system. In this case, the key for decryption is distributed only to the subscriber. On the other hand, since a non-subscriber can obtain limited information related to image information that is broadcast / transmitted or recorded, it is easy to determine whether or not to subscribe. In particular, in a pay-per-view system that pays a fee for each program, it is frequently determined whether or not to pay a fee. Therefore, the function of reproducing an image incompletely is also effective in reducing the burden on the user side who makes the determination.
[0014]
In a video-on-demand system, for example, when reading information recorded on a remote server through a pay public network, the user must bear the communication cost. For this reason, it is unlikely that a user who does not have a key will bother to access this information even though the image cannot be viewed at all. However, if the method shown in the present invention is used, even a user who does not have a key can view at least a part of the image, so that there is a high possibility of accessing the encrypted information even if the communication cost is borne. Become. This also leads to effective promotion to non-subscribers and is effective in increasing the number of subscribers.
[0015]
In general, an object appearing in an image changes with time, and the importance of each object changes depending on the situation of the place. Therefore, if an object to be encrypted (for example, a specific character) is fixed, there is a high possibility that the effect of encryption is insufficient. This problem can be addressed by switching the object to be encrypted. However, if a large number of objects are encrypted at the same time, the amount of processing for encryption and descrambling increases, resulting in a problem that the terminal becomes complicated and expensive. As a practical countermeasure against this problem, a method of limiting the number of objects encrypted at the same time can be considered. When the encryption and descrambling processing is performed by hardware, the number of encryptors and descramblers can be reduced, or the processing can be realized even by a relatively low-speed device. Also, when this process is performed in software, the required processing speed can be reduced, so that the processing can be realized by a slower CPU or the processing speed can be spared for other processes. Is possible.
[0016]
FIG. 5 shows a configuration example of an image transmission or recording apparatus 501 in which the number of objects to be encrypted is always one or less. The parts indicated by the common numbers in FIGS. 1 to 4 indicate the same parts. The region dividing unit 103 performs region division processing on the input original image signal 102. As in the case of FIG. 1, the outputs 104, 105, and 106 of the area dividing unit are image signals related to the objects obtained by the area division. Encoding units 107, 108, and 109 perform encoding processing on each of the divided signals, and encoded bit streams 110, 111, and 112 are output. These encoded bit streams are input to the changeover switch 502. This change-over switch is controlled so that an encoded bit stream related to one or less objects always passes through the encryption unit 303. In the encryption unit, encryption processing is performed using the encryption key information 306. Therefore, one or less of the output bit streams 503, 504, and 505 of the changeover switch are always encrypted. This information is supplied to the data multiplexing unit 506, and a multiplexed bit stream 507 is output to the communication path or recording device. As in the past, identification information as to whether or not the bit stream is encrypted is incorporated in the encoded bit stream for each object. In addition, regarding the process of selecting an object to be encrypted, it is considered that the method of manually performing the process while considering the effect of encryption on the viewer is particularly effective when real time property is not required. When this real-time property is not required, it corresponds to a case where encoded image information for recording in a recording device is created in an image database or a video on demand system.
[0017]
FIG. 6 shows a configuration example of the receiving / reading device 601 for the bit stream transmitted or recorded by the device of FIG. 1 to 5 indicate the same parts. After the multiplexed bit stream 507 is received or read, the data division unit 602 divides the data into three bit streams 503, 504, and 505. Each encoded bit stream incorporates identification information indicating whether or not the bit stream is encrypted. Based on this identification signal, the changeover switch 603 supplies one or less of the three bit streams to the descrambling unit 403. In the descrambling unit, the cipher is decrypted using the information 404 relating to the key for decrypting the cipher. The encoded bit streams 110, 111, and 112 obtained in this way are decoded by the decoders 204, 205, and 206. The image signals 104, 105, and 106 that are the outputs of the respective decoders are combined by an image signal combining unit 206 to obtain a reproduced image signal 207.
[0018]
At this time, this apparatus knows in advance that the number of encoded bit streams related to an input object is always 1 or less. Unless such an arrangement exists in advance between the encoding side and the playback side, the playback side will have a large number of encoded bitstreams to cope with the worst case (when many bitstreams are encrypted). Must have the ability to simultaneously unlock the cipher. Therefore, the restriction on the number of encrypted bitstreams is effective in simplifying the terminal hardware or reducing the processing amount of the terminal software.
[0019]
【The invention's effect】
According to the present invention, when the encrypted digital image information is received, it is possible to see the important parts in the image except for the encryption process, and the sender of the image information has the key for decrypting. Certain information can be provided to recipients who do not have it.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of an image transmission / recording apparatus that performs content-based coding.
FIG. 2 is a diagram illustrating a configuration example of an image reproducing device that receives and reads image information encoded by content-based coding.
FIG. 3 is a diagram illustrating a configuration example of an image transmission / recording apparatus that performs encryption processing on a specific object in an image.
FIG. 4 is a diagram illustrating a configuration example of an image reproducing apparatus that receives and reads out image information obtained by performing encryption processing on a specific object in an image.
FIG. 5 is a diagram illustrating a configuration example of an image transmission / recording apparatus that performs encryption processing while switching a target object with respect to one or less objects in an image.
FIG. 6 is a diagram illustrating a configuration example of an image reproducing apparatus that receives and reads out image information obtained by performing encryption processing while switching a target object with respect to one or less objects in an image.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 101 ... Image information transmission / recording device based on Content-based coding, 102 ... Original image information, 103 ... Region dividing unit, 104 ... Background image signal, 105 ... Image signal related to person A, 106 ... Image signal related to person B , 107, 108, 109... Image encoding unit, 110... Encoded bit stream related to background, 111... Encoded bit stream related to person A, 112... Encoded bit stream related to person B, 113, 304, 506. , 114 ... multiplexed bit stream, 201 ... image information receiving / reading device based on Content-based coding, 202, 402, 602 ... data dividing unit, 203, 204, 205 ... image decoding unit, 206 ... image signal Synthesizer, 207 ... reproduced image output, 301 ... image based on content-based coding with encryption function Information transmitting / recording device, 302 ... encryption unit, 303 ... encrypted encoded bit stream relating to person B, 305, 507 ... encrypted multiplexed bit stream, 306 ... key information for encryption, 401: Image information receiving / reading device based on content-based coding with decryption function, 403: Decryption unit, 404: Key information for decrypting, 501: Function for performing encryption while switching target object Image information transmission / recording device based on content-based coding, 502, 603... Bitstream changeover switch, 503, 504, 505... Encoded bitstream switched between application / non-application of encryption, 601. Image information receiving / reading device based on Content-based coding with the function of decrypting while switching.

Claims (7)

Encoding bitstreams for all objects after performing encoding processing for each object in the image independently on the original image information, applying encryption processing only to the encoding bitstream for one or more specific objects A method for transmitting or recording image information, characterized in that the upper limit of the number of objects to be output after being multiplexed and to which encryption processing is applied to the encoded bitstream is less than the number of objects in the image .   When the image information output according to the method of claim 1 is received or read out and reproduced, the encoded bitstream which is not encrypted is reproduced correctly, but the encrypted encoded bitstream has a key for decryption. An image reproducing method characterized in that it cannot be correctly reproduced without it. It has means for independently encoding the original image information for each object in the image and means for performing encryption processing on the information, and the specific information among the information encoded by the encoding means The number of objects to which only the encoded bitstream related to one or a plurality of objects is encrypted and then the encoded bitstream related to all objects is multiplexed and output, and the encoded bitstream is subjected to the encryption processing The image information transmission or recording apparatus is characterized in that the upper limit of the number is defined to be less than the number of objects in the image.   A means for receiving and reading out the image information output according to the method of claim 1 and a means for reproducing the encrypted information using a key for decrypting the encoded information. An image reproducing apparatus, wherein a corresponding object is reproduced correctly, but an object corresponding to an encrypted encoded bitstream cannot be reproduced correctly without a key. 4. The apparatus for transmitting or recording image information according to claim 3, wherein an object to be encrypted is switched when an encryption process is applied to an encoded bit stream of the object.   An object corresponding to an encoded bitstream that has been encrypted by switching the encoded bitstream to which decryption processing is applied to information output according to the transmission or recording method of image information according to claim 5 is correctly performed. The image reproducing apparatus according to claim 4, wherein the image reproducing apparatus can reproduce the image.   An image system comprising the image information transmission or recording device according to claim 3 and the image reproduction device according to claim 4 or 6.

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