JP2009225477A - Electronic watermark embedding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the detection reliability of embedded watermark information while maintaining favorable usability in circulation. <P>SOLUTION: An electronic watermark embedding apparatus for embedding prescribed watermark information into prescribed contents processed in time sequence is provided with: an embedding means which has a function of embedding watermark information into contents with a plurality of different embedding modes; and a period designation means which designates zones on a time base for the content wherein the embedding mode in a period on the time base which specifies the embedding of the watermark information is made different from at least the adjacent zones, and the content is a unit of data for generating a moving image, and a plurality of unit data arranged in sequence according to the time base are included in the each zone. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic watermark embedding apparatus, and is suitable for application to, for example, embedding electronic watermark information in a moving image to perform copyright protection, image alteration detection, various information recording, and the like.

  As a conventional moving image digital watermark embedding apparatus, there is one disclosed in Patent Document 1 below.

  Conventionally, in this type of moving image digital watermark embedding device, the influence on the image quality is taken into consideration, and the digital watermark is embedded in the frame constituting the moving image with the weakest possible strength. At this time, the same watermark information is embedded in all the frames constituting the moving image in order to enable statistical judgment in later digital watermark detection.

  In other words, in the detection based on this statistical judgment, the contents of images in consecutive frames constituting a moving image usually change dynamically with the passage of time, but since the watermark information is unchanged, a large number of frames The watermark information can be obtained by extracting a statistically invariant portion from the image.

Japanese Patent Application Laid-Open No. 11-341452

  However, for example, by editing, a plurality of moving image contents having different watermark information (such as copyright holder information) are cut or combined in the time axis direction to form a new moving image content. Since the copyright holders and the like are different for each section of the new moving image content that is configured, different copyright holder information (for example, the name and ID of the copyright holder) is embedded for each section. In the conventional method, detection of digital watermark may not be successful, and the reliability of watermark information detection is low.

  In general, the boundary between sections cannot be known in advance, and the watermark information itself changes from section to section. Therefore, the correct statistical information can be obtained with respect to detection of any watermark information by interference with watermark information embedded in adjacent sections. This is because it cannot make a proper judgment.

  Of course, if boundary instruction data that explicitly indicates the boundary of the section is distributed together with the moving image content, the above-described extraction of the invariant portion is executed only within the section defined by the boundary instruction data. Although it is considered possible to make a statistical judgment, it is not preferable to distribute such boundary instruction data separately from the moving image content because the distribution of the moving image content is hindered.

  On the other hand, editing related to moving image content is not only performed in the time axis direction, but may be performed in the spatial axis direction, that is, in one frame, similarly to a still image. In this case, a plurality of contents having different watermark information (for example, copyright holder information) are mixed in each frame constituting the moving image.

  When the watermark information cannot be normally detected, for example, some information items of the watermark information in the frame (for example, the copyright holder C1 among the watermark information of the content related to the copyright holder C1's work). Even if use (for example, the content user visually checks) is permitted only with respect to the copyright information (such as the name and ID of the user), information items of other watermark information (for example, the copyright holder C2's work) In such content, a case where content purchaser information secretly embedded in order to specify a distribution route of unauthorized copying is also detected and viewed together.

  That is, there is a possibility that the conventional method cannot appropriately manage the watermark information.

  Which of the various information items that can be included as watermark information should be visible to the user (for example, want to keep the name of the copyright holder visible, but want to keep the content purchaser information confidential) Is originally determined for each content according to the intention of the copyright holder, etc., but as long as the watermark information for different copyright holders is embedded in the same frame in the same way, such fine processing Is difficult to do.

  That is, with the conventional method, there is a possibility that control using watermark information cannot be performed appropriately.

  In order to solve this problem, in the present invention, in an electronic watermark embedding apparatus that embeds predetermined watermark information in predetermined content processed in time series, (1) watermark information for the content in a plurality of different embedding modes Embedded execution means having a function of executing the embedded processing; and (2) section specifying means for specifying a section on the time axis with respect to the content, and (3) at least for a section adjacent on the time axis And (4) the content is unit data constituting a moving image, and (5) each section has a plurality of units that are continuous on the time axis. Data is included.

  According to the present invention, since watermark information can be accurately detected by performing statistical processing on content, the reliability of watermark information detection can be improved while maintaining high distribution. .

  This makes it possible to appropriately manage each piece of watermark information embedded in the content, and to appropriately perform control based on the watermark information.

  In the present invention, since an embedding mode having a relatively weak tolerance strength can be used, it is possible to maintain a high quality of content after embedding processing.

It is the schematic which shows the structural example of the principal part of the electronic watermark embedding apparatus according to the area for moving images concerning 1st Embodiment. It is the schematic which shows an example of the moving image content used by the 1st-8th embodiment. It is the schematic which shows the structural example of the principal part of the digital watermark embedding mechanism used with the digital watermark embedding apparatus according to the moving image section according to the first embodiment. It is the schematic which shows the structural example of the principal part of the digital watermark embedding system which concerns on 2nd Embodiment. It is the schematic which shows the structural example of the principal part of the digital watermark embedding system which concerns on 3rd Embodiment. It is the schematic which shows the structural example of the principal part of the digital watermark embedding system which concerns on 4th Embodiment. It is the schematic which shows the structural example of the principal part of the electronic watermark detection apparatus classified by area for moving images which concerns on 5th Embodiment. It is the schematic which shows the structural example of the digital watermark detection and reliability calculation part used with the digital watermark detection apparatus according to the moving image section concerning 5th Embodiment. It is the schematic which shows the structural example of the reliability accumulation | storage and analysis part used with the electronic watermark detection apparatus according to the area for moving images concerning 5th Embodiment. It is operation | movement explanatory drawing of 5th Embodiment. It is the schematic which shows the structural example of the principal part of the electronic watermark detection apparatus classified by area for moving images which concerns on 6th Embodiment. It is the schematic which shows the structural example of the principal part of the digital watermark detection by all the detection methods and the reliability calculation part which are used with the digital watermark detection apparatus classified by area for moving images concerning 6th Embodiment. It is the schematic which shows the structural example of the principal part of the reliability accumulation | storage and analysis part used with the electronic watermark detection apparatus according to the moving image section concerning 6th Embodiment. It is the schematic which shows the structural example of the principal part of the multiple digital watermark detection apparatus for moving images concerning 7th Embodiment. It is the schematic which shows the structural example of the principal part of the multiple digital watermark detection apparatus for moving images concerning 8th Embodiment.

(A) Embodiments Each embodiment will be described below with reference to an example in which the digital watermark embedding apparatus according to the present invention is applied to a digital watermark embedding apparatus for moving image content.

  Digital watermarking is a technology that secretly embeds watermark information such as copyright holder information that can specify a copyright holder such as a content creator or copyright holder in the content itself.

  What items are provided as information items of watermark information to be embedded in content is originally determined for each content according to the intention of the copyright holder, etc., but watermark information is embedded in content by digital watermarking. In many cases, the purpose is copyright protection, so the information item of the watermark information is not always sufficient as the information item of the copyright information, and it is distinguished from the different contents produced by the same producer. Content identification information for identifying the content itself, content purchaser information for identifying the person who purchased the content, content user information for sequentially identifying the person (or computer terminal) who used the content via the network, Whether copying is permitted or not, and the maximum number of copies to allow It is preferred to include a variety of information items such as number of copies present.

  Information such as content identification information, content purchaser information, content user information, and the current number of copies is effective in identifying the fact of copyright law violations and illegal distribution channels, and a copying apparatus that performs copying If it corresponds to the copy number limit by the watermark information, it is possible to automatically prohibit copying exceeding the number limit value according to the copy number limit value and the current copy number.

  Note that watermark information embedded by digital watermark is not an essential component of content and is a kind of noise for content, so embedding watermark information inevitably results in content quality degradation, but the degree of quality degradation Can be suppressed by various methods.

  A feature common to the first to eighth embodiments is that the boundary instruction data or the like can be used by embedding watermark information in a time axis direction (for each section) or by another method in the same unit data. It is possible to distinguish and detect different watermark information.

(A-1) Configuration of First Embodiment A configuration example of the moving image section-specific digital watermark embedding device 10 according to the present embodiment is as shown in FIG. The embedding device 10 may be used by connecting to an editing device (not shown) having a function of editing moving image content (digital moving image).

  In FIG. 1, the embedding device 10 includes a digital watermark embedding unit 11, an embedding method designating unit 12, an embedding information encoding unit 13, and an embedded code switching unit 14.

  Of these, the embedded information encoding unit 13 is a part that encodes the watermark information (embedded information) to be embedded in the moving image content in a form that is easy to embed. The encoding unit 13 is supplied with the watermark information S3 and synchronization information S10 for performing processing in synchronization with each section of the moving image content from the editing device or the like, and encodes the watermark information S3. The obtained code S4 is output.

  The watermark information S3 includes four different types of watermark information S3A to S3D, and the codes obtained by encoding the watermark information S3A to S3D include four types S4A to S4D. The code S4A corresponds to the watermark information S3A, the code S4B corresponds to the watermark information S3B, the code S4C corresponds to the watermark information S3C, and the code S4D corresponds to the watermark information S3D.

  Here, the watermark information can be said to be different watermark information if at least one of the information items described above is different. For example, when there are four copyright holders of the moving image content that is the basis of editing, and the presence or absence of the copyright holder information in the information items of the watermark information or the contents thereof differ corresponding to the four copyright holders Is different watermark information, but not limited to this, if there is a difference in the presence or content of the content identification information, if there is a difference in the presence or content of the content purchaser information, the presence or absence of the content user information is different In this case, it can be said that the watermark information is different when the copy number limit value or the copy number limit value is different, or when the current copy number is different or the value is different.

  In addition, in the synchronization information S10, for each section, a section start frame number SN that is a frame number of a frame at which the section starts, a section end frame number EN that is a number of a frame at which the section ends, and the section information are embedded in the section. Information (list) related to the correspondence with the watermark information (identifier WD designating the watermark information) may be included.

That is, the structure of the list is
(Section start frame number SN: section end frame number EN, watermark information identifier WD)
It is.

  Encoding by the encoding unit 13 needs to be completed at a sufficiently early timing in accordance with the synchronization information S10.

  The embedding code switching unit 14 that receives the synchronization information S11 corresponding to the synchronization information S10 and the codes S4A to S4D from the encoding unit 13 performs embedding when receiving the frame number S2 from the editing apparatus or the like existing outside. This is a part that selects a code corresponding to the section and outputs it to the embedding unit 11.

  The moving image content (frame series) S1 edited by the editing device is as shown in FIG. FIG. 2 shows time-series frames F1 to F29 that are sequentially processed in time. Among these, the frames TF1 to F7 from the frame F1 of the frame number 1 to the frame F7 of the frame number 7 constitute the moving image content section TD1, and similarly, the frames F8 to F14 from the frame number 1 to the frame number 7 are configured. The section TD2 is configured, the sections TD3 are configured by the frames F15 to F20 from the frame number 1 to the frame number 6, and the section TD4 is configured by the frames F21 to F29 from the frame number 1 to the frame number 9.

  Since the length of each section in the time axis direction (that is, the number of frames) is dynamically determined according to the content of the editing work, various sections of various lengths can be mixed in one moving image content S1. Assuming that the number indicating the relative frame order within each moving image content before editing is used as the frame number, each section does not necessarily start from the frame of frame number 1 as shown in the figure. Depending on the editing work, it may happen that the order of frames is changed in one section or that some frames are deleted, so the frame numbers in one section may not necessarily be consecutive numbers. In FIG. 2, it is assumed that all the sections start from a frame with frame number 1, and the frame numbers within one section are consecutive numbers. If the frame number is changed or deleted in accordance with the editing work, the frame number can be changed before being input to the embedding apparatus 10 to obtain a continuous number. Similarly, by changing the frame number, the frame number of the first frame in all sections can be set to a predetermined value (for example, frame number 1).

  Here, the watermark information to be embedded is the same for each frame belonging to one arbitrary section (the presence or absence of each information item and the contents thereof are the same), but should be embedded between frames in different adjacent sections. The watermark information is different (the presence or absence of each information item or its contents are different).

  Since the time is earlier in the left direction in FIG. 2, the frame F1 with the frame number 1 is processed earliest in the drawing, and the frame F29 with the frame number 9 is processed latest.

  When the frame number series is as shown in FIG. 2, it is possible to detect the boundary of the section only by monitoring the appearance of frame number 1 without using the above-described list.

  In addition, although there is a field used in television or the like as unit data relating to an image, since a frame is usually used in processing in a computer, the frame is also used in this embodiment.

  Assuming the moving image content S1 and the frame number S2 in FIG. 2, the switching unit 14 outputs the code S4A in the section TD1 of frame numbers 1 to 7, and the code in the section TD2 of frame numbers 1 to 7. S4B is output, and the code S4D is output in the section TD4 of frame numbers 1 to 9.

  The switching unit 14 also has a function of supplying a control signal S6 corresponding to the synchronization information S11 to the embedding method specifying unit 12.

  The embedding method specifying unit 12 is a part that transmits the embedding method specified by the embedding method specifying signal S9 according to a predetermined specifying algorithm as the embedding method control signal S5 to the embedding unit 11 at a timing according to the control signal S6.

  The digital watermark embedding unit 11 that receives the embedding method control signal S5 from the embedding method specifying unit 12, receives the codes S4A to S4D from the switching unit 14, and receives the moving image content S1 from the editing device. This is a portion in which any one of the codes S4A to S4D is embedded by the embedding method specified by the embedding method control signal S5 for each frame constituting the frame.

  If a code is not embedded in each frame, it is only necessary to embed. However, if a code is already embedded in each frame, the new code may be embedded after deleting the code. Good. However, in order to execute the erasure accurately, it is necessary to perform an erasure operation corresponding to the embedding method used for embedding the code to be erased.

  An image frame representation method such as frames F1 to F29 includes a pixel representation that represents an image with a pixel (pixel) as a minimum unit, and a plurality of cosine waves with different phases and amplitudes (or frequencies) with a cosine wave as a minimum unit. The watermark information embedding method includes a frequency expression for representing an image by superposition, and a compressed expression for representing a moving image by a frame having a reference image and a prediction frame that can be generated as difference information from the reference image. Are different depending on these expression methods.

  Specifically, pixel representation uses RGB representation using the three primary colors of light, R (red), G (green), and B (blue), and Y (luminance), Cr, and Cb (color difference). There are YCrCb expressions to be performed, frequency expressions include expressions using DCT (discrete cosine transform), expressions using Fourier transform, expressions using wavelet transform (HARR transform), and compressed expressions are MPEG1. There are expressions corresponding to MPEG2 and MPEG2, and various embedding methods can be used for any one of these expressions. Therefore, the embedding methods that can be used in this embodiment are extremely diverse, and various image processing (including affine transformation (including image enlargement, reduction, rotation, etc.), filter processing, compression processing, etc.), processing, transmission, etc. Even after receiving it, the watermark information can be stored on the content to a considerable degree (that is, the strength against image processing etc. is not so weak), and various excellent features that can suppress degradation of image quality to a level acceptable to the user However, the types of image processing that can be supported, the types of processing, the degree of image quality degradation, and the contents of images that are easy to apply differ depending on the method of embedding. The type of image processing and type of processing that each moving image content is predicted to receive later, the degree of acceptable image quality degradation, Depending on various conditions such as the image contents of the image content, it may be to select the most appropriate embedding method.

  It is important that the embedding method used in this embodiment has excellent performance as a single embedding method, but in addition, the relationship between embedding methods applied to each adjacent section is important. . This is because the relationship between the embedding methods applied to adjacent sections directly affects the correctness of statistical judgment described later.

  In general, the embedding method is the embedding method because there is a trade-off between the strength of resistance to image processing, processing, transmission, etc. of the embedded watermark information and the image quality of the embedded image. A method having a relatively weak resistance strength is used. However, if it is possible to perform embedding with a relatively strong tolerance without degrading the image quality, it is natural that such embedding is also preferable in this embodiment.

  In this embodiment, four types of embedding methods MV1 to MV4 are prepared as candidates from these various embedding methods, and any one of the embedding methods MV1 to MV4 is used when embedding is executed. And

  Here, four types of embedding methods MV1 to MV4 are prepared, but the number of embedding methods to be prepared is generally N. Here, N is a natural number, but may be more or less than 4 as necessary. If it is sufficient to execute an embedding method that clearly differs between any two adjacent sections (for example, sections TD2 and TD3), at least two (N = 2) embedding methods are prepared. It's enough.

  However, in the detection device (for example, the detection device 60 shown in FIG. 7) corresponding to the embedding device 10 of the present embodiment, as described later, when detecting watermark information from the moving image content S1 after embedding the watermark information, first, First, it is necessary to statistically execute identification of each section and identification of the embedding method used in each section. However, there is a case where the length of one section may be extremely short, and resistance strength is strong as an embedding method. Considering the use of a relatively weak one, it is preferable to select another embedding method between sections that are close to each other on the time axis even if they are not necessarily adjacent to each other. In that respect, it can be said that it is advantageous to increase the number N of embedding methods (for example, MV1 to MV4) prepared as candidates.

  In general, in the case of a moving image, the number of frames processed per unit time is constant (for example, 30 frames per second), so whether each section is close on the time axis is simply determined. It can be determined based on the number of frames.

  Therefore, the embedding method designation signal S9 determined by the designation algorithm may sequentially and cyclically designate the embedding method in the order of MV1, MV2, MV3, MV4, MV1,. If necessary, it is also preferable to be able to cope with forced designation from outside in preference to the designation algorithm.

  The moving image content S1 after watermark information is embedded by the embedding unit 11 is output from the embedding unit 11 as moving image content S8.

  The embedded moving image content S8 is distributed through a network such as a LAN (local area network) or the Internet, and distributed among content purchasers and content users, or recorded on a recording medium such as a DVD. Will be distributed.

  The internal configuration of the embedding unit 11 may be as shown in FIG.

  In FIG. 3, the embedding unit 11 includes a frame sorting unit 20, embedding mechanisms 21 </ b> A to 21 </ b> N, and an embedded code recording unit 22.

  The embedding mechanisms 21A to 21N are mechanisms corresponding to different embedding methods. In the present embodiment, since the embedding methods are MV1 to MV4, the number of embedding mechanisms 21A to 21N is four. Here, it is assumed that the embedding mechanism 21A has a function of executing the embedding method MV1, the embedding mechanism 21B has a function of executing the embedding method MV2, and the embedding mechanism 21N has a function of executing the embedding method MV4.

  The frame distribution unit 20 is a part that distributes the moving image content S1 to any of the embedding mechanisms 21A to 21N according to the embedding method control signal S5.

  The embedded code recording unit 22 is a part that temporarily records the input codes S4A to S4D and supplies them to the embedding mechanisms 21A to 21N. Since all the frames belonging to one section are embedded with the same watermark information (code), the recording of the code in the code recording unit 22 is basically maintained only for the corresponding section.

  The operation of the present embodiment having the above configuration will be described below.

(A-2) Operation of First Embodiment If moving image content S1, frame number S2, and watermark information S3A to S3D are input to the embedding device 10, the embedding device 10 starts operation at any time. Can do. Information that is meaningful to an operator who operates the editing device or the embedding device 10, a copyright holder who is a distribution source of moving image content, and a content purchaser or content user who is a distribution destination is the moving image content S1. , Frame number S2, and watermark information S3A to S3D and their combinations.

  However, when the embedding device 10 operates, in addition to these pieces of information, the synchronization information S10 and the embedding method designation signal S9 are also supplied to the embedding device.

  When the embedding methods MV1 to MV4 prepared as candidates by the embedding method designating signal S9 are cyclically designated in the order of MV1, MV2, MV3, MV4, MV1,... The distribution destination of the moving image content S1 is cyclically changed in the order of 21A, 21B,..., 21N, 21A,. The method designation is changed for each frame or section.

  Accordingly, if the embedding method MV1 is applied to the section TD1 shown in FIG. 2 unless forcedly specified from the outside, the embedding method MV2 is applied to the section TD2, and the embedding method MV3 is applied to the section TD3. The embedding method MV4 is applied to the section TD4.

  Also, even if there is a compulsory designation from the outside, if the compulsory designation specifies the same embedding method as the adjacent section (previous section), the designation is rejected or a warning is issued. It is preferable to encourage the change. If such a designation is allowed, statistically detecting the boundary of the section and identifying the section cannot be performed normally, and there is a high possibility that the detection of the watermark information of the immediately preceding section as well as the section is hindered. Because.

  While the code (watermark information) is embedded in an arbitrary section (for example, TD1) based on the corresponding embedding method (for example, MV1) by the corresponding embedding mechanism (for example, 21A), the synchronization is performed. The contents of the watermark information (for example, S3A) to be embedded are maintained by the operations of the encoding unit 13 and the switching unit 14 according to the information S10, the frame number S2, and the like.

  In one section (for example, TD2), watermark information having exactly the same content is embedded by the same embedding method (for example, MV2), and in a section adjacent to the section (for example, TD1 and TD3), the section (TD2 Only when an embedding method (for example, MV1, MV3) different from that of () is used, the boundary of the section can be detected statistically accurately and accurate watermark information can be detected.

  As described above, various embedding methods can be used as the embedding methods MV1 to MV4 prepared in the present embodiment. Here, as an example, an embedding method corresponding to the frequency expression will be described.

  In this embedding method, when 1 is embedded as a 1-bit value constituting the watermark information S3A to S3D (codes S4A to S4D), a conversion coefficient of a certain coordinate on the frame (for example, F1) is calculated from the surrounding conversion coefficients. When embedding 0, the embedding is performed by making the conversion coefficient of a certain coordinate on the frame smaller than the reference value obtained from the surrounding conversion coefficients. By adjusting the difference from the reference value so as to make the difference from the original value of the conversion coefficient as small as possible, the influence on the image quality can be suppressed.

  However, as described above, even with this embedding method, generally, at many coordinates on the frame, the original value of the conversion coefficient at a certain coordinate is considered to be almost equal to the reference value obtained from the peripheral conversion coefficient, so The strength of is basically in a trade-off relationship with the high image quality. If the difference from the reference value is increased to increase the tolerance strength, the image quality is impaired. If the difference from the reference value is reduced with emphasis on image quality, the tolerance strength becomes relatively weak. If the tolerance strength is weak, the above-described image processing or the like will not reverse the magnitude relationship between the conversion coefficient and the reference value and destroy the embedded watermark information.

  Whether or not the inversion of the magnitude relationship actually occurs depends on the type of image processing or the like applied to the moving image content S8 with embedded watermark information, and may differ depending on the content of the image of each frame. As a result of the image processing, even if the magnitude relationship between a certain conversion coefficient on a certain frame (for example, F1) and a certain reference value is reversed, it is not necessarily reversed in another frame (for example, F7) in the same section. Absent.

  However, in the case of moving image content, generally, the image contents of consecutive frames (for example, F1 and F2) hardly change and have a strong correlation. Therefore, statistical judgment is made based on the results detected from as many frames as possible. Need to do.

  For example, when embedding is performed based on the magnitude relationship with the reference value obtained from the peripheral transform coefficients, the difference from each reference value (each transform coefficient-reference value), that is, the reliability for each frame of one code (intraframe code reliability) Degree) is added to each frame, and finally, if the absolute value of the sum total is a positive number exceeding a certain threshold value, it is 1; At this time, it can be said that the larger the absolute value, the higher the reliability of the code value over a plurality of frames (interframe code reliability).

  However, when such a value (interframe code reliability) is accumulated beyond the boundary of the section, the watermark information is different in the embedded section, so the code in the previous section is temporally reversed. If a code is embedded, the interframe code reliability may be lowered, and accurate statistical judgment may not be possible.

  In addition, if importance is attached to image quality, it is necessary to embed watermark information with a relatively low intensity (corresponding to the small absolute value of the difference from the reference value in the above example) for each frame. It is difficult to accurately determine the boundary of the section based only on the watermark information detected from the position frame (for example, the frame F7 positioned at the end of the section TD1 or the frame F8 positioned at the beginning of the section TD2). It is. Furthermore, since not all the codes move in the direction in which the inter-frame code reliability decreases, it is also impossible to make a judgment on the increase / decrease (change direction) of the inter-frame code reliability.

  In order to solve this, in this embodiment, a technique of embedding a watermark with a different embedding method for each section is adopted. For example, when an embedding method for embedding watermark information (code) in Fourier coefficients is adopted, the Fourier coefficients are grouped in advance and the watermark information is embedded in different groups in adjacent sections.

  For example, in the embedding method MV1 used in the interval TD1, watermark information is embedded in the Fourier coefficient group FA, and in the embedding method MV2 used in the interval TD2, the watermark information is added to another group FB of Fourier coefficients. Is embedded.

  Such a relationship is formed between embedding methods (here, MV1 and MV2) applied to each adjacent section, and a detection method corresponding to each embedding method is executed on the detection side. When a watermark is read from a coefficient with no watermark information embedded, a code showing a random distribution in terms of white noise will be generated, so the intra-frame code reliability is accumulated for the coefficient with no watermark information embedded. The absolute value of the result is small and almost 0, and in the coefficient in which the regular watermark information is embedded, the absolute value of the accumulation result of the intraframe code reliability, that is, the interframe code reliability, is large and can exceed the threshold. This makes it possible to accurately identify sections and to detect watermark information.

  Similarly, it is possible to eliminate the influence of image processing.

  Further, when embedding in the wavelet transform coefficient, it is possible to embed while shifting the phase. Normally, discrete wavelet transform always selects only even-numbered transform coefficients when downsampling, but trying to select even-numbered transform coefficients or odd-numbered transform coefficients at each level, At the time of reconstruction, the coefficient can be moved to the position (even-numbered position or odd-numbered position) selected at the time of downsampling. When wavelet transformation is performed up to n levels, in the case of an image (two-dimensional signal), wavelet transformation corresponding to 2n × 2n phase shifts can be performed.

  Here, if the watermark information is embedded in the level n conversion coefficient, the watermark information cannot be read from the coefficient obtained by wavelet conversion at a phase different from that in which the embedding is performed, and a random code is generated.

  If detection is performed by a method that does not correspond to the watermark information embedding method embedded at the time of detection as described above, a random code is basically detected. For example, if the difference from the reference value is accumulated, (For example, when a detection method corresponding to the embedding method MV4 is applied to the interval TD3 in which the watermark information is embedded by the embedding method MV3), a random sign (a negative value and a positive value appear and add together) Statistically becomes 0), and the accumulated value is not greatly affected. By detecting the randomness of such a detection code at the time of detection, the boundary of a section is detected, and detection of watermark information embedded in the next section is started.

  In particular, in this embodiment, different embedding methods are used in adjacent sections that are highly likely to be confused and sections that are close in time, so that accurate watermark information detection is performed by reliably identifying sections. Is possible.

(A-3) Effect of First Embodiment As described above, according to the present embodiment, different watermark information is obtained using different embedding methods (MV1 to MV4) for each section of the moving image content (S1). Since it is embedded, the detection apparatus can accurately detect watermark information based on statistical judgment, and can realize highly reliable watermark information detection.

  Since the reliability of watermark information detection is high, it is possible to appropriately manage each piece of watermark information embedded in the moving image content, and it is also possible to appropriately perform control based on the watermark information.

  In the present embodiment, since the embedding method having a relatively low strength can be used, the quality of moving image content is sufficiently high even after embedding watermark information.

  In addition, in this embodiment, since it is not necessary to use the boundary instruction data or the like, the circulation of moving image content is high.

(B) Second Embodiment Hereinafter, only differences between the present embodiment and the first embodiment will be described.

  The present embodiment proposes a specific configuration for realizing real-time characteristics that are not necessarily clear in the first embodiment.

  Here, the real-time property is a property that a moving image content in which watermark information is embedded can be immediately output at a predetermined frame interval (for example, 30 frames per second) required for a moving image upon request. It is.

(B-1) Configuration and Operation of Second Embodiment A configuration example of the moving image section-specific real-time digital watermark embedding system 30 according to the present embodiment is as shown in FIG.

  In FIG. 4, the embedding system 30 includes a moving image section-specific digital watermark embedding device 31, a frame reading unit 32, and a frame counting unit 33.

  Among these, the function of the embedding device 31 is basically the same as that of the embedding device 10 of the first embodiment. Also, in FIG. 4, the function of each signal given the same reference numerals S1, S2, and S8 as in FIG. 1 is basically the same as in the first embodiment.

  However, the embedding device 31 of the present embodiment has a function of outputting an embedding completion signal S24 every time embedding of watermark information (code) for one frame in the moving image content S1 is completed. This is different from the embedding device 10 of the embodiment.

  After receiving the embedding start signal S21 instructing embedding of the watermark information, the frame reading unit 32 reads and reads each frame of the moving image content S22 that is sequentially captured each time the embedding completion signal S24 is received. This is the part that outputs the read notification signal S23 each time. The moving image content S22 may be the same as the moving image content S1 shown in FIG. 2, and the frame reading unit 32 basically supplies each read frame sequence to the embedding device 31 as it is. This frame sequence is the moving image content S1 shown in FIG.

  The frame count unit 33 that receives the read notification signal S23 is a part that changes the contents of the frame number to be output every time the read signal is received. This change may be a simple increment, for example.

  Since the embedding start signal S21 is also supplied to the frame count unit 33, the embedding start signal S21 is supplied every time a new section starts and the count value is set to an initial value (here, 0). If reset, the sequence of frame numbers output by the frame count unit 33 is exactly the same as in FIG.

  In the embedding system 30 of the present embodiment, a different embedded watermark information is embedded for each section specified for each frame of the moving image content S22 captured in real time, and a moving image in which the watermark information has been embedded. The image content S8 can be output at a predetermined frame interval necessary for a moving image (for example, 30 frames per second), and such output can be started immediately after receiving a request. Yes.

  In the first embodiment, it is necessary to generate the frame number S2 externally and supply it together with the moving image content (frame sequence) S1. In the present embodiment, the moving image content S22 is externally supplied. If supplied, the frame number S2 can be generated in real time within the embedded system 30.

(B-2) Effect of Second Embodiment According to the present embodiment, an effect equivalent to that of the first embodiment can be obtained.

  In addition, in this embodiment, embedding different watermark information in different sections by different embedding methods can be reliably processed in real time.

  Therefore, the embedding system (30) of this embodiment is suitable for mounting on a server on a network that distributes moving image content, for example.

(C) Third Embodiment Hereinafter, only the points of this embodiment different from the first and second embodiments will be described.

  Even in the embedding device 10 of the first embodiment, it is possible to write the moving image content (S8) embedded with watermark information that is finally output to a file generated on a recording medium such as a DVD. This proposes a specific configuration for this purpose that was not necessarily clear in the first embodiment.

(C-1) Configuration and Operation of the Third Embodiment FIG. 5 shows a configuration example of the moving image section sequential digital watermark embedding system 40 according to the present embodiment.

  In FIG. 5, the embedding system 40 includes an electronic watermark embedding device 41 for each moving image section, a frame reading unit 42 from a file, a frame count unit 43, and a frame writing unit 44 for a file.

  Among these, the function of the embedding device 41 is basically the same as that of the embedding device 31 of the second embodiment. Further, in FIG. 5, the function of each signal given the same reference numerals S1, S2, S3 (A to D), S8, S20, S22, and S23 as in FIG. 4 is basically the same as in the second embodiment.

  The embedding device 41 of the present embodiment has a function of outputting the embedding completion signal S24 every time embedding of watermark information (code) for one frame of the moving image content S1 is completed. It is the same as the embedding device 31 of the form.

  Basically, the frame reading unit 42 of this embodiment corresponds to the frame reading unit 32, and the frame count unit 43 corresponds to the frame count unit 33.

  However, the frame reading unit 42 according to the present embodiment calculates the start address of the next frame to be read based on the frame number S2 output from the frame count unit 43, and each time an embedding completion signal S24 is received, a new calculation result (new The operation of reading a frame from a file is repeated based on (a leading address), and the moving image content S22 is read.

  The count value of the frame count unit 53 is initially set to the initial value 0. If necessary, the count value can be reset to an initial value at any time by a signal similar to the embedding start signal S21.

  Here, it is assumed that there is one file from which the frame is read and that the edited video content is stored in the file. However, it is not always necessary to have one file from which the frame is read. Therefore, if the content of the editing work is logically determined separately, it is also possible to switch the file to be read according to the content of the editing work. In this case, each moving image content before editing is stored in each reading destination file, and the contents of editing work are physically realized by the reading.

  In the present embodiment, the moving image content S8 after embedding watermark information is stored in the file as the moving image content S25 by the frame writing unit 44.

  Thereafter, a recording medium (for example, a DVD) on which the content of the file is recorded is distributed in the market, for example, by being sold to a purchaser of moving image content.

  Also in this writing, the frame number S2 output from the frame count unit 43 is used.

(C-2) Effect of Third Embodiment According to the present embodiment, an effect equivalent to the effect of the first embodiment can be obtained.

  In addition, in this embodiment, it is easy to store the moving image content in the file after embedding watermark information in the moving image content read from the file.

(D) Fourth Embodiment Hereinafter, only the points of this embodiment different from the first to third embodiments will be described.

  In the first to third embodiments, it is basically assumed that some kind of watermark information is embedded in all the sections. However, in the present embodiment, some of a plurality of consecutive sections on the moving image content are selected. The present invention proposes a specific configuration for realizing a function of embedding watermark information only for a section and not for another section.

(D-1) Configuration and Operation of Fourth Embodiment FIG. 6 shows a configuration example of the partial digital watermark embedding system 50 in a moving image according to the present embodiment.

  In FIG. 6, the embedding system 50 includes a moving image digital watermark embedding device 51, a frame reading unit 52 from a file, a frame counting unit 53, a frame writing unit 54 to a file, and a frame reading control unit 55. And.

  Among these, the function of the embedding device 51 is basically the same as that of the embedding device 31 of the second embodiment. Further, in FIG. 6, the function of each signal given the same reference numerals S1, S2, S3 (A to D), S8, S20, S22, S23 as FIG. 5 is basically the same as that of the third embodiment. Further, although the embedding method designation signal S9 in FIG. 6 is not shown in FIG. 5, this signal has already been described in the first embodiment and is naturally used also in the third embodiment. Signal. Further, the frame reading unit 52 of this embodiment corresponds to the frame reading unit 42, the frame count unit 53 corresponds to the frame count unit 43, and the frame writing unit 54 corresponds to the frame writing unit 44.

  Therefore, the substantial difference between the present embodiment and the third embodiment is limited to a portion related to the frame reading control unit 55 and a portion related to the embedding section designation signal DC1.

  The frame reading control unit 55 causes the counter of the frame count unit 55 to set the embedding start frame number SN and the embedding end frame number EN in the list based on the embedding section designation signal DC1.

  When the count value of the frame count unit 53 is not within the range from the embedding start frame number SN to the embedding end frame number EN, control is performed so that watermark information is not embedded in the read frame, When it is within the range, control is performed so that watermark information is embedded.

  How the watermark information can be controlled so as not to be embedded depends on the functional specifications of the embedding device 51 and the like. For example, effective watermark information S3A to S3D is not supplied or predetermined invalidity is specified. It is possible to prevent embedding by supplying appropriate watermark information, or by including information indicating whether or not the embedding operation is possible in the frame number S2 supplied from the frame count unit 53.

  Depending on the functional specifications of the embedding device 51, even if the configuration shown in FIG. 6 is not adopted, the effective watermark information S3A to S3D is not supplied, or predetermined invalid watermark information is supplied. There is a possibility that watermark information can be embedded only in a desired part of the section. Therefore, in this case, for example, watermark information can be embedded only in a desired partial section also in the first embodiment shown in FIG.

  Of course, a plurality of sets of the embedding start frame number SN and the embedding end frame number EN set in the frame count unit 53 by the frame reading control unit 55 may be used.

  Further, as a special usage method, it is possible not to set one set of the embedding start frame number SN and the embedding end frame number EN in the frame count unit 53 or to set them continuously without a break. When set continuously without a break, the content of the moving image content S25 that is finally output is exactly the same as the moving image content S25 of the third embodiment.

(D-2) Effects of the fourth embodiment According to the present embodiment, it is possible to obtain the same effects as the effects of the first and third embodiments.

  In addition, in the present embodiment, it is easy to embed watermark information only in a part of continuous sections.

(E) Fifth Embodiment Hereinafter, only the difference of this embodiment from the first to fourth embodiments will be described.

  The present embodiment relates to a detection apparatus for detecting the watermark information embedded in the first to fourth embodiments. Therefore, the configuration of the present embodiment basically corresponds to the configurations of the first to fourth embodiments, and many of the points have already been described in the first embodiment.

(E-1) Configuration and Operation of Fifth Embodiment A configuration example of the moving image section-specific digital watermark detection apparatus 60 according to the present embodiment is as shown in FIG. The detection device 60 can be connected to a playback device for playing back the moving image content S8, a copy device for copying, and the like.

  In FIG. 7, the detection device 60 includes a digital watermark detection / reliability calculation unit 61, a reliability accumulation / analysis unit 62, an embedded information decoding unit 63, a list of detected information and its sections. Part 64.

  Among them, the reliability calculation unit 61 detects the code embedded in each frame in the moving image content S8 by the detection method based on the detection method switching control signal SC1 from the analysis unit 62, and the intra-frame code related to the code. In the part for calculating the reliability (absolute value of the difference from the reference value), the detected code and the calculated intra-frame code reliability are input to the analysis unit 62.

  Note that a general detection method is sufficient if it is possible to specify whether a certain bit of watermark information embedded in content is 1 or 0 (that is, it is sufficient if watermark information can be detected). The procedure for obtaining such intra-frame code reliability is not provided.

  When the embedding device on the watermark information embedding side prepares MV1 to MV4 as embedding methods as in the first embodiment, for example, the reliability calculation unit 61 in the detection device 60 corresponds to these embedding methods. Detection methods NV1 to NV4 may be prepared. Here, the detection method NV1 corresponds to the embedding method MV1, the detection method NV2 corresponds to the embedding method MV2, the detection method NV3 corresponds to the embedding method MV3, and the detection method NV4 corresponds to the embedding method MV4.

  Of course, it is necessary that these correspondences correspond not only to the use of the method, but also to fully correspond to the detailed procedures within the method. Depending on the implementation of the detection method, it can be described as a procedure for each detection method (for example, NV1), including how to use the method described here.

  For example, as described above, when the embedding method divides the Fourier transform coefficients into groups and embeds the watermark information in one of the groups, the corresponding detection method also groups them in the same way, and 1 You must be able to select one group for detection.

  Similarly, when the embedding device selects an embedding method using the phase shift of the wavelet transform, the reliability calculation unit 61 must be able to select the detection method by designating the phase shift.

  Further, the procedure for detecting the watermark information from these coefficients must be completely compatible with the embedding procedure. For example, as described above, when the watermark information is embedded using the magnitude relationship with the reference value obtained from the peripheral coefficients, the detection side must similarly detect the watermark information using the magnitude relationship with the reference value. .

  The configuration of the reliability calculation unit 61 is, for example, as shown in FIG.

(E-1-1) Configuration Example of Digital Watermark Detection and Reliability Calculation Unit 61 In FIG. 8, the reliability calculation unit 61 includes a frame distribution unit 66, detection mechanisms 65A to 65N, a detection result integration unit 67, It has.

  Among these, the detection mechanism 65A has a function of executing the detection method NV1, the detection mechanism 65B has a function of executing the detection method NV2, and the detection mechanism 65N has a function of executing the detection method NV4. is doing.

  Since the number of embedding methods MV1 to MV4 is at least two as described above, the number of detection methods NV1 to NV4 is also required to be at least two. However, the detection device 60 and the embedding device 10 do not necessarily correspond one-to-one, and one type of embedding device 10 may have a function of embedding corresponding to a plurality of types of detection devices 60. The number of detection methods installed in 60 and the number of embedding methods installed in the embedding device 10 are not necessarily the same.

  The reliability calculation unit 61 including the frame distribution unit 66 is roughly divided into two operation modes, one of which is a search mode for performing the above-described section identification and embedding method identification. One is a detection mode that is executed in order to detect watermark information after identification of a section.

  In the search mode, for example, even when the section TD1 shown in FIG. 2 in which watermark information is embedded by the embedding method MV1 is processed, the section cannot be identified yet, and the section embedding method is MV1. Since it has not been identified, it is necessary to execute all detection methods NV1 to NV4 corresponding to all embedding methods MV1 to MV4 prepared as candidates. Therefore, the distribution unit 66 distributes the moving image content S8 to all the detection mechanisms 65A to 65N when in the search mode.

  As long as the moving image content that has to be processed within a limited time is handled for each successive frame, when the distribution unit 66 distributes to all the detection mechanisms 65A to 65N, the detection mechanisms 65A to 65N are simultaneously parallel. It is desirable to be able to execute each detection method NV1 to NV4.

  On the other hand, in the detection mode, since the watermark information is detected using only one detection mechanism corresponding to one specified detection method (for example, NV1), the distribution unit 66 has one corresponding detection mechanism ( For example, the moving image content S8 is supplied only to 65A).

  Whether the distribution unit 66 (and the reliability calculation unit 61) takes the search mode or the detection mode is determined by the detection method switching control signal SC1 supplied from the analysis unit 62.

  The detection signals DT1 to DTN obtained as a result of executing the detection methods NV1 to NV4 corresponding to the detection mechanisms 65A to 65N in the search mode (and the detection mode) are integrated by the detection result integration unit 67, and are integrated as the integrated detection signal DTS. The data is supplied to the analysis unit 62 arranged at the subsequent stage of the reliability calculation unit 61 in FIG.

The content of the integrated detection signal DTS output from the detection result integration unit 67 differs between the search mode and the detection mode. That is, in the search mode, a list composed of the contents (DTX) of the detection signals DT1 to DTN obtained by all the detection unit mechanisms 65A to 65N and the detection mechanism identifier (65X) for specifying each detection mechanism is output. The structure of the list is
(Detection mechanism identifier 65X, detection result DTX)
It becomes.

  On the other hand, the integrated detection signal DTS in the detection mode is composed of only the detection signal output from only one specified detection mechanism (for example, 65A).

  Although the detection signal (for example, DT1) output from each detection mechanism (for example, 65A) in the search mode is the above-described intra-frame code reliability (for example, the absolute value of the difference (each transform coefficient-reference value)). On the other hand, the detection signal (for example, DT1) output from each detection mechanism (for example, 65A) in the detection mode is information indicating whether the value of the difference is positive or negative in this example.

  Since the procedure for obtaining the reliability in this manner is obtained by adding a procedure for obtaining the absolute value of the difference to the procedure for obtaining the difference value between each conversion coefficient value and the reference value, The detection method procedure executed by each detection mechanism (for example, 64A) may be different between the search mode and the detection mode, but a sign with a positive / negative sign is sent to the analysis unit 62 as it is, and the analysis unit 62 side positive / negative as necessary. If the process of generating an absolute value is performed without the sign, the procedure of the detection method executed by the detection mechanism can be the same in the search mode and the detection mode.

  The configuration of the analysis unit 62 that outputs the detection method switching control signal SC1 is, for example, as shown in FIG. In relation to the reliability calculation unit 61, the analysis unit 62 determines whether or not the section can be identified and whether or not the detection method is identified (that is, the embedding method is identified), and the detection method is determined. When the determination result that the identification of the image is completed is obtained, the detection method switching control signal SC1 is changed, and the frame distribution unit 66 (and the reliability calculation unit 61) is changed from the search mode to the detection mode.

(E-1-2) Configuration Example of Analysis Unit 62 In FIG. 9, the analysis unit 62 includes a reliability and code distribution unit 70, reliability accumulation units 71A to 71N, and a detection method determination unit 72. Yes.

  Of these, the distribution unit 70 distributes the reliability and code to the reliability accumulation units 71A to 71N for each detection method.

  Receiving this, the reliability accumulating units 71A to 71N accumulate the respective intra-frame code reliability to obtain the inter-frame code reliability. Here, the reliability accumulation unit 71A corresponds to the detection mechanism 65A, the reliability accumulation unit 71B corresponds to the detection mechanism 65B,..., And the reliability accumulation unit 71N corresponds to the detection mechanism 65N.

  Usually, after sufficient accumulation is performed, the interframe code reliability accumulated in any one of the reliability accumulation units 71A to 71N (for example, 71A) is the other reliability. Compared to the inter-frame code reliability stored in the storage unit (for example, 71B to 71N), it is prominently larger, but when the section to which the frame to be processed changes (for example, when the section changes from TD1 to TD2), The inter-frame code reliability of the reliability accumulation unit (for example, 71B) different from the above is prominently increased.

  The detection method determination unit 72 identifies the detection method according to the procedure according to steps P10 to P12 shown in FIG.

  In step P10 shown in FIG. 10, it is checked whether the current operation mode of the reliability calculation unit 76 is the search mode or the detection mode. If the search mode is the search mode, the process branches to the No side.

  In Step P12 following the No side of Step P10, it is inspected whether or not the detection method has been identified. This is because, for example, only the interframe code reliability stored in one reliability storage unit among the reliability storage units 71A to 71N exceeds a predetermined threshold, and the frames stored in other reliability storage units. The detection method may be specified (identified) when the inter-code reliability is less than the threshold.

  When it can be specified, only the detection mechanism corresponding to the specified detection method among the detection mechanisms 65A to 65N is operated (Yes side of P12), and when it cannot be specified, all of the detection mechanisms 65A to 65N are operated. The search is continued with all detection methods NV1 to NV4 (No side of P12). Here, branching to the Yes side in Step P12 means occurrence of a transition from the search mode to the detection mode.

  In Step P11 following the Yes side of Step P10, it is inspected whether or not the codes are randomly distributed like white noise. If distributed randomly, the interframe code reliability is low, otherwise the interframe code reliability is high.

  If distributed randomly, Step P11 branches to Yes and continues the search mode. If not distributed randomly, Step P11 branches to No and continues to accumulate results. The branch on the No side in Step P11 means continuation of the detection mode, and the branch on the Yes side means a transition from the detection mode to the search mode.

  When the reliability calculation unit 61 is in the detection mode for a certain section (for example, TD1) of the moving image content S8, it is used if the next section (for example, TD2) is processed past the boundary of the section. Since the detection method inside does not conform to the embedding method, it is necessary to transition from the detection mode to the search mode.

  When a new transition is made to the search mode, the code reliability stored in the reliability storage units 71A to 71N until then needs to be reset to an initial value (for example, 0).

  While the detection mode is instructed by the detection method switching control signal SC1, the detection method determination unit 72 uses the interframe code reliability of the corresponding reliability accumulation unit (for example, 71A) as the analysis result signal DD in FIG. Is supplied to the decoding unit 63 arranged in the subsequent stage.

  The decoding unit 63 performs decoding corresponding to the encoding of the encoding unit 13 in the first embodiment on the analysis result signal DD, and outputs a decoded signal DE. For example, when a difference from the accumulated reference value is passed as a result, a binary code is obtained by assigning 1 if the absolute value is a positive value exceeding the threshold value, and assigning 0 if the absolute value is negative. At the time of embedding from the binary code, for example, the watermark information embedded by the decoding method corresponding to the encoding method used by the encoding unit 13 is decoded.

  The list creation unit 64 subsequent to the decoding unit 63 creates a list of pairs of watermark information sequentially decoded and a section (for example, TD1) in which the watermark information is embedded, based on the decoded signal DE. It will be a thing. When the detection of the entire watermark information embedded in one section (for example, TD1) of the moving image content S8 is completed and the creation of the list is completed, the created list is output. The list is a detection result of the final watermark information by the detection device 60, and is output from the detection device 60 as a detection list LT1.

  In general, in the case of moving image content, if the length of the entire moving image content is, for example, about one hour, it is only necessary to detect watermark information (in this case, the detection list LT1) every few minutes. In many cases, the shorter the time interval is, the more precisely the management of watermark information and the control based on the watermark information can be performed.

(E-2) Effects of Fifth Embodiment As described above, according to the present embodiment, it is possible to obtain the same effect as the effect of the first embodiment by cooperating with the first embodiment. it can.

  That is, in the detection device (60) of the present embodiment, even when different watermark information is embedded using different embedding methods (MV1 to MV4) for each section of the moving image content (S1) on the embedding device side, Since it is possible to accurately detect watermark information based on statistical judgment, it is possible to realize highly reliable watermark information detection.

  The high reliability of watermark information detection makes it possible to appropriately manage each watermark information embedded in the moving image content, and to appropriately control the copy device and the playback device based on the watermark information. It is also possible to do this.

  For example, when the watermark information requests that the copyright owner's name and ID be displayed on the screen, the playback device connected to the detection device (60) responds to the request by the copyright owner's name or An ID or the like can be displayed on the screen.

  In the present embodiment, since the embedding method having a relatively low tolerance strength can be used, the quality of moving image content is sufficiently high even after embedding watermark information.

(F) Sixth Embodiment Hereinafter, only the points of this embodiment different from the fifth embodiment will be described.

  In the fifth embodiment, the search mode and the detection mode exist, and only one detection mechanism is operated in the detection mode. However, in this embodiment, all the detection mechanisms are always operated, and search and detection are performed in parallel. To run.

  In the fifth embodiment, only one detection mechanism is operated in the detection mode, which is advantageous in that the amount of calculation is small. However, a certain section (for example, TD1) of the moving image content (S8) ends and the next is completed. When a section (for example, TD2) is processed, a transition from the detection mode to the search mode occurs, and a certain processing time is required until the necessity of this transition is recognized. For a while after the processing of TD2) is started, the detection mode (invalid detection mode) by the detection method corresponding to the immediately preceding section (for example, TD1) continues, and watermark information cannot be detected effectively.

  Further, after the transition to the search mode after this invalid detection mode and the identification of the section and the identification of the detection method are completed, the transition to the new detection mode can be made.

  If the period of the invalid detection mode or the period of the search mode is long, the ratio of the effective detection mode decreases as a whole, and there is a high possibility that the management of watermark information and control by watermark information cannot be performed appropriately. Become. For example, even if an attempt is made to limit the number of copies based on watermark information, depending on the functional specifications of the copying apparatus, there is a possibility that unauthorized copying may be performed while the watermark information itself is not normally detected.

  The present embodiment solves such problems.

(F-1) Configuration and Operation of Sixth Embodiment A configuration example of the moving image section-specific digital watermark detection apparatus 75 according to the present embodiment is as shown in FIG.

  In FIG. 11, the detection device 75 includes a digital watermark detection and reliability calculation unit 76 by all detection methods, a reliability accumulation and analysis unit 77, an embedded information decoding unit 78, and detected information A section creation unit 79 for the section.

  Among them, the reliability calculation unit 76 corresponds to the reliability calculation unit 61, the analysis unit 77 corresponds to the analysis unit 62, the decoding unit 78 corresponds to the decoding unit 63, and the list creation unit 79 uses the list creation. Corresponds to the section 64.

However, in this embodiment, since there is no difference between the search mode and the detection mode in the reliability calculation unit 61, the function for switching the mode between both modes is mounted in the reliability calculation unit 76 and the analysis unit 77. Not. Therefore, in the present embodiment, the detection method switching control signal SC1 is not supplied from the analysis unit 77 to the reliability calculation unit 76.

  In response to this, the internal configuration of the reliability calculation unit 76 does not have a component corresponding to the distribution unit 66 as shown in FIG. However, in other respects, the reliability calculation unit 76 is the same as the reliability calculation unit 61, in which the detection mechanism 80A corresponds to the detection mechanism 65A, and the detection mechanism 80B corresponds to the detection mechanism 65B. The detection mechanism 80N corresponds to the detection mechanism 65N.

  Similarly, in FIG. 12 showing an internal configuration example of the analysis unit 77, the analysis unit 77 is the same as the analysis unit 62 except that it does not have a function of outputting the detection method switching control signal SC1, and the reliability accumulation is performed. The unit 83A corresponds to the reliability accumulation unit 71A, the reliability accumulation unit 83B corresponds to the reliability accumulation unit 71B,..., The reliability accumulation unit 83N corresponds to the reliability accumulation unit 71N, and determines the detection method. The unit 84 corresponds to the detection method determination unit 72.

  In the present embodiment having no search mode and no detection mode, since the detection mechanisms 80A to 80N and the reliability accumulation units 83A to 83N are always operating, even in a period corresponding to the invalid detection mode described above, The reliability accumulation units 83A to 83N continue to accumulate the interframe code reliability.

  Further, the accumulation status (decompression status) of the inter-frame code reliability can be constantly monitored, and the period corresponding to the invalid detection mode period or the search mode period is reduced, which corresponds to the valid detection mode. The period to do becomes long.

  In the present embodiment, the interframe code reliability stored in the reliability storage units 83A to 83N may be periodically reset to an initial value (for example, 0).

(F-2) Effect of Sixth Embodiment According to this embodiment, an effect equivalent to the effect of the fifth embodiment can be obtained.

  In addition, in this embodiment, the ratio of the period during which effective watermark information can be detected increases, and the availability is improved.

  As a result, the possibility that the management of the watermark information and the control by the watermark information cannot be performed appropriately is reduced. For example, even if an attempt is made to limit the number of copies by the watermark information, the probability of occurrence of illegal copying is sufficiently high. Can be reduced.

(G) 7th Embodiment Below, only the point from which this embodiment differs from the 1st-4th embodiment is demonstrated.

  Although the present embodiment relates to an embedding device, the embedding device of the first to fourth embodiments embeds different watermark information in the time axis direction, whereas the embedding device of this embodiment Embed different watermark information in the axial direction.

  That is, in the embedding according to the present embodiment, different watermark information is mixed in one frame.

  The necessity for embedding different watermark information in the spatial axis direction as described above occurs, for example, when content editing is performed in the spatial axis direction.

(G-1) Configuration and Operation of Seventh Embodiment A configuration example of the moving picture multiple digital watermark embedding device 85 according to the present embodiment is as shown in FIG. As apparent from FIG. 14, the structure of the outline of the embedding device 85 is quite different from that of the first embodiment, but there are many common points in the details.

  In FIG. 14, the embedding device 85 includes a plurality of embedding mechanisms 87 </ b> A to 87 </ b> M and an embedding information encoding unit 86.

  Of these, the number of M (in principle, M may be any number as long as it is a natural number of 2 or more, but in the example of FIG. 14, M is larger than 4), the functions of the embedding mechanisms 87A to 87M are substantially the same. Since they are the same, here, the description will proceed mainly focusing on the embedding mechanism 87B. The encoding unit 86 is a part corresponding to the encoding unit 13.

  The embedding mechanism 87B embeds the code MKB allocated to itself among the codes (watermark information) MKA to MKM into the moving image content (frame series) received from the immediately preceding embedding mechanism 87A, and the embedded moving image content S8A Has a function of passing to an embedding mechanism (not shown) immediately after. Since the moving image content S8A received from the embedding mechanism 87A is already embedded with the code MKA by the receiving unit 87A, the moving image content S8B output from the embedding mechanism 87B is embedded with the codes MKA and MKB. Become. Thus, a new code is embedded in the moving image content S1 every time it is supplied to a new embedding mechanism.

  The foremost embedding mechanism 87A does not have the immediately preceding embedding mechanism, and the last embedding mechanism 87M does not have the immediately following embedding mechanism, but for the embedding mechanism 87A, the supply source of the moving image content S1 in which the watermark information is not embedded Can be regarded as the immediately preceding embedding mechanism. For the embedding mechanism 87M, the output destination of the moving image content S8M in which all the codes MKA to MKM are embedded in each frame can be regarded as the immediately following embedding mechanism.

  The embedding method used for embedding the codes MKA to MKM may be the same embedding methods MV1 to MV4 as in the first embodiment. However, in this embodiment, each embedding method depends on each embedding method. Care must be taken so that the embedding of the codes MKA to MKM does not interfere. If such interference occurs, there is a possibility that the same situation as in the case of an overwriting attack that is a kind of attack on the digital watermark may occur, and it is difficult to detect normal watermark information on the detection device side. Because there is a possibility of becoming.

  It is also conceivable that the watermark information based on the codes MKA to MKM and the embedding method are associated in advance by a list format or the like. In this case, when creating the list, consideration can be given so that the interference does not occur.

(G-2) Effect of Seventh Embodiment According to the present embodiment, different watermark information can be embedded in the spatial axis direction.

  Thereby, on the detection side, it is possible to detect only a part of the watermark information among the watermark information (corresponding to MKA to MKM) embedded in the spatial axis direction.

(F) Eighth Embodiment Hereinafter, only points in which the present embodiment is different from the first to seventh embodiments will be described.

  The present embodiment proposes a detection device corresponding to the embedding device 85 of the seventh embodiment.

(F-1) Configuration and Operation of Eighth Embodiment A configuration example of the moving image multiple digital watermark detection apparatus 88 according to the present embodiment is as shown in FIG.

  15, the detection device 88 includes detection mechanisms 89A to 89M, reliability and code storage units 90A to 90M, decoding units 91A to 91M, a detection information list creation unit 92, and a detection completion signal integration unit 93. And.

  Among these, the function of any one of the detection mechanisms 89A to 89M basically corresponds to the function of any one of the detection mechanisms 65A to 65N. However, while the detection mechanisms 65A to 65N correspond to an embedding method for embedding different watermark information in the time axis direction, the functions of the detection mechanisms 89A to 89M are the same as those of the embedding mechanisms 87A to 87M. Accordingly, it is qualitatively different in that it corresponds to an embedding method for embedding different watermark information in the spatial axis direction.

  The detection mechanism 89A corresponds to the embedding mechanism 87A, the detection mechanism 89B corresponds to the embedding mechanism 87B,..., And the detection mechanism 89M corresponds to the embedding mechanism 87M.

  Since the embedding device 85 and the detection device 88 do not necessarily correspond one-to-one, the embedding mechanism 87A provided in the embedding device 85 of the seventh embodiment is similar to the relationship between the detection device 60 and the embedding device 10 described above. The number of .about.87M and the number of detection mechanisms 89A to 89M provided in the detection device 88 of the present embodiment are not necessarily the same.

  However, in the embedding devices of the first to fourth embodiments, if there is a section in which the watermark information cannot be detected in the middle of the time axis, the influence also affects the detection of the watermark information in the subsequent section or the immediately preceding section. Therefore, it is necessary that the watermark information of all sections can be detected by the detection device (for example, 60), but in the case of the present embodiment, there is basically no such limitation.

  Therefore, in this embodiment, watermark information may be embedded in the moving image content S8M by an embedding method that cannot be detected by the detection device 88. That is, of the different watermark information embedded in the spatial axis direction, a part of the watermark information can be detected by the detection device 88, but the other watermark information cannot be detected in this embodiment.

  For this reason, in this embodiment, it is possible to set different usage rights for the watermark information for each user of the detection device 88, and some detection mechanisms are used by the detection mechanism usage right information RT1 shown in FIG. It is also possible to control so that only (for example, 89A) is operated and the other detection mechanisms (for example, 89B to 89M) are not operated.

  Note that each of the detection mechanisms 89A to 89M of the present embodiment has a function of supplying the detection completion signals CLA to CLM to the detection completion signal integration unit 93 when the detection of the watermark information is completed.

  In response to this, the detection completion signal integration unit 93 receives the detection completion signals CLA to CLM from all the detection mechanisms 89A to 89M, or the detection mechanism use right information RT1 in advance among the detection mechanisms 89A to 89M. When the detection completion signals are supplied from all the detection mechanisms that are known to operate based on the above, the integrated detection completion signal CLS is output to the outside of the apparatus.

  The integrated detection completion signal CLS can be used, for example, by the copy apparatus to synchronize with the detection apparatus 88.

  The reliability (the intraframe code reliability) detected by the detection mechanism (for example, 89A) and the code are accumulated in the corresponding accumulation unit (for example, 90A) among the accumulation units 90A to 90M, and sufficient reliability is obtained. When the accumulation is confirmed, the accumulation result is accumulated in the corresponding decoding unit among the decoding units 91A to 91M. Here, the accumulation units 90A to 90M correspond to the reliability accumulation units 83A to 83N, and the decoding units 91A to 91M correspond to the decoding unit 78. In the present embodiment, watermark information is transmitted in the spatial axis direction. Therefore, it is not necessary to identify the section, and it is only necessary to identify the watermark information.

  Further, in the present embodiment, since different decoding units 91A to 91M are provided for the respective detection mechanisms 89A to 89M, it is possible to simultaneously decode the watermark information.

  However, when strict parallelism is not required for decoding, decoding can be performed in a time division manner using one decoding unit or a number of decoding units smaller than the number of detection mechanisms 89A to 89M. is there.

  The list creation unit 92 that receives the decoded signals DEA to DEM as the decoding results output from the decoding units 91A to 91M outputs the detection list LT2 corresponding to the detection list LT1. The detection list LT2 includes the content of the decoded signal supplied from the decoding unit corresponding to the detection mechanism controlled to operate according to the detection usage right information RT1 (for example, 91A corresponds to 89A). ing.

(H-2) Effect of Eighth Embodiment According to the present embodiment, watermark information can be appropriately detected even when different watermark information is embedded in the spatial axis direction.

  For example, it is possible to detect only a part of watermark information among watermark information (corresponding to MKA to MKM) embedded in the spatial axis direction according to detection mechanism use right information (RT1).

(I) Other Embodiments In the first to eighth embodiments described above, moving image content has been described as an example. However, the present invention is not limited to moving images, and multi-processing that is processed in time series such as audio data and music data. It can be widely applied to media.

  In addition, since the features of the first to fourth embodiments and the seventh and eighth embodiments are not mutually exclusive, it is possible to construct a device or system having these features together.

  For example, in the seventh and eighth embodiments, different watermark information is embedded only in the same unit data (with different embedding methods), but different watermark information is also embedded in the time axis direction in addition to the multiple embedding methods in the same unit data. You may do it.

  Furthermore, encoding and decoding in the first to eighth embodiments can be omitted.

  The watermark information may be encrypted before being embedded. As a result, even when the embedding method is known to a third party, it is possible to withstand an attack and maintain high security.

  Furthermore, in order to make a difference in the embedding method, a method of changing the embedding frequency region, a method of embedding by changing the phase in the wavelet transform, a method of quantization when changing the actual coefficient value, or selecting a coefficient It is conceivable to use a method by selecting a coefficient value correction method for embedding a watermark, such as selecting a method for changing a coefficient value depending on the magnitude relationship.

  In the above description, the present invention is realized mainly by hardware, but the present invention can also be realized by software.

  DESCRIPTION OF SYMBOLS 10, 31, 41, 51, 85 ... Digital watermark embedding apparatus, 11 ... Digital watermark embedding part, 12 ... Embedding method designation | designated part, 13 ... Encoding information encoding part, 14 ... Embedding code switching part, 21A-21N ... Embedding mechanism, 30, 40, 50 ... digital watermark embedding system, 60, 75, 88 ... digital watermark detection device, 61 ... digital watermark detection and reliability calculation unit, 62 ... reliability accumulation and analysis unit, 63 ... embedded Information decoding unit, 64... Detected information and its list creation unit, 65A to 65N... Detection mechanism, S1, S8... Moving image content, TD1 to TD4 ... interval, S3A to S3D. ... embedding method, F1-F29 ... frame.

Claims (4)

In an electronic watermark embedding device that embeds predetermined watermark information for predetermined content processed in time series,
Embedding execution means having a function of executing watermark information embedding processing for the content in a plurality of different embedding modes;
Section specifying means for specifying a section on the time axis for the content,
At least for the section adjacent on the time axis, the embedding mode that defines the embedding process of watermark information is different,
The content is unit data constituting a moving image,
Each of the sections includes a plurality of unit data continuous on a time axis. The digital watermark embedding apparatus according to claim 1.
The embedding mode includes
An electronic watermark embedding apparatus, comprising: an embedding method element that defines an embedding method and / or an encoding method element that defines an encoding method of the watermark information. The digital watermark embedding apparatus according to claim 2,
The embedding execution means includes
An input unit that inputs unit data while synchronizing with the embedding process of watermark information; a count unit that generates a unit data number by counting the number of unit data input at the start of the embedding process;
An embedding mode control unit that executes the embedding process for unit data in an embedding mode that has been designated,
In accordance with the unit data number generated by the counting unit, it is determined to which section the unit data input at that time belongs, and according to the determination result, designation of the embedding mode for the embedding mode control unit is determined. An electronic watermark embedding device characterized by being changed. The digital watermark embedding apparatus according to claim 3, wherein the unit data is recorded on a recording medium.
Read address designation means for inputting the next unit data to the input unit by performing address designation on the recording medium based on the unit data number at each time point;
An electronic watermark embedding apparatus comprising: a write address designating unit for writing unit data subjected to embedding processing to a recording medium by performing address designation based on a unit data number at each time point.

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