JP2004312568A - Detecting method of electronic watermark information based on format information - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and method for efficiently detecting watermark information on the basis of format information acquired from content data. <P>SOLUTION: The method includes a first step of acquiring the format information from the content data and extracting an area to be a detection target of contents on the basis of the format information, and a second step of detecting information from the extracted area of the contents. A plurality of detection areas predetermined from the format information are determined and when information cannot be detected from the extracted detection area, the other detection area is extracted to try the detection of information again. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a digital watermarking technique for digital data, particularly image data.
[0002]
[Prior art]
From the viewpoint of copyright protection of literary works (hereinafter, referred to as contents) such as image data and music, digital watermark technology has been receiving attention. Digital watermarking technology inserts predetermined information (called watermark information) into digital data (hereinafter simply referred to as data) by changing a data value at a predetermined position using a predetermined rule. This is a technique that makes it difficult to detect the predetermined information from the digital data unless at least the predetermined rule is used.
[0003]
Taking image data as an example, according to a predetermined rule, information about the purchaser of the image data and the like is inserted into a predetermined position of the image data in an invisible form, and when illegally copied, according to the above predetermined rule By using the pixel value at the predetermined position, the predetermined information inserted from the illegally copied data is detected, and the person who made the illegal copy (that is, the purchaser) is specified.
[0004]
Non-Patent Document 1 describes the digital watermarking technology.
[0005]
In addition, a method has been proposed in which copy control information of a dedicated device such as a DVD drive is embedded in moving image data to prevent unauthorized copying of the moving image data on a DVD medium.
[0006]
Non-Patent Literature 2 and Non-Patent Literature 3 describe techniques for controlling unauthorized copying of DVD media using the digital watermark.
[0007]
In addition, image data may be subjected to various image processing such as geometric transformations such as enlargement, reduction, compression, decompression, and aspect conversion, and clipping in the process of being used and distributed after information insertion of the data. There is.
[0008]
When the image data in which such watermark information is embedded is subjected to a transformation such as an image filter or a geometric transformation such as enlargement / reduction or rotation, that is, when the digital data is transformed, the watermarking is performed by the transformation. The pixel value at the predetermined position changed by the insertion also changes. This makes it impossible to detect the watermark. As an example of a technique for solving such a problem, there is a technique described in Patent Document 1.
[0009]
Also, as disclosed in Non-Patent Document 4, there is known a method of embedding 1-bit information by operating thousands of pixels. In this method (“digital watermark using statistical properties”), artificial pixel operations are statistically detected using the properties of natural images. Therefore, when watermark information is detected, original image data before embedding a watermark is not required. Also, with this watermarking method, watermark information is relatively unlikely to be lost even if data is deformed or trimmed.
[0010]
Image formats such as the number of pixels of an input image to be embedded and detected are various depending on the environment in which the embedding process is performed and the type and use of the content to be handled. For example, taking moving images handled for broadcasting as an example, there are dozens of types of formats. The format of the moving image is described in detail in Non-Patent Document 5. Other factors that determine the image format include the number of pixels of the image, the color expression method (RGB format, YUV format, YCrCb format, CMYK format, etc.), the number of color gradations, and the like. It is also conceivable that an image is handled as compressed data such as JPEG or MPEG. Non-Patent Document 6 describes a method of embedding a watermark in an MPEG compressed image. Elements unique to a moving image include the number of horizontal lines constituting a moving image, an interlace / progressive method, and the like.
[0011]
[Non-patent document 1]
I. Echizen, H .; Yoshiura, T.M. Arai, H .; Kimura, T.W. Takeuchi "General Quality Maintainance Module for Motion Picture Watermarking", IEEE Transactions on Consumer Electronics, Vol. 45, no. 4, pp. 1150--1158, NOVEMBER 1999.
[Non-patent document 2]
J. Bloom, I. Cox, T .; Kalker, J .; Linnartz, M .; Miller, C.I. Traw "Copy Protection for DVD Video" Proc. IEEE, Vol. 87, no. 7, pp. 1267276 (1999)
[Non-Patent Document 3]
Iwamura, Sugaya, Sasaki, Kawara, Yamazaki, Endo, Moriyama “Video Watermark” Pioneer R & D, Vol. 11, No. 2, pp. 5054 (2001)
[Patent Document 1]
U.S. Pat. No. 5,636,292
[Non-patent document 4]
W. Bender, D.A. Gruhl, N.W. Morimoto: Technologies for data hiding, Proc. SPIE, Vol. 2020, pp. 2420-2-440 (1995)
[Non-Patent Document 5]
CQ Publishing Company, "Basics of Digital TV Video Signals / Moving Image Processing," Interface, January 2000, pp. 67-71.
[Non-Patent Document 6]
I. Cox, J .; Kilian, T.W. Leighton, T .; Shamoon: A Secure, Robust Watermark for Multimedia, Proceedings of Information Hiding (LNCS 1174), pp. 185-206 (1996)
[0012]
[Problems to be solved by the invention]
As described above, there are a plurality of image formats of input image data to be embedded and detected. In the future, the number of image formats is expected to increase in accordance with the diversification of environments in which content is distributed and viewed. However, the conventional technology is a technology targeting a specific image format, and no specific measures are taken to cope with an increase in formats expected in the future.
[0013]
For example, in the above-described unauthorized copy control technology for DVD media using a digital watermark, the format of a moving image that is currently supported is a standard image format with a frame size of 720 × 480 pixels, but in the future, a high-definition image with a larger number of pixels will be used. There is also a possibility of supporting a high definition format such as 1920 × 1080 pixels. As the storage in the HDTV format medium, (1) the case where the image is stored in the format as it is, or (2) the case where the image is stored after being converted (down-converted) into another format such as a standard image format, can be considered. In the future, when a drive apparatus that reproduces these plural image formats appears, it is necessary for the unauthorized copy prevention technology using the digital watermark to detect information from the above (1) and (2). However, in the process of detecting digital watermark information, if information is detected by the conventional technology, the detection process is performed assuming any format. However, there are problems such as an increase in hardware size and an increase in detection processing time.
[0014]
Therefore, there is a need for a more efficient watermark detection processing technique.
[0015]
[Means for Solving the Problems]
The present invention provides an efficient information detection technique applicable to the above-described multi-format image reproducing apparatus.
[0016]
The present invention provides information detecting means for extracting a detection area of an image using format information of an input image and depending on the format information. ADVANTAGE OF THE INVENTION According to this invention, the calculation process to the image area unnecessary for detection and the detection process from an unnecessary assumed format are omitted, and the efficiency and speed of the detection process can be increased. In particular, the present invention can be an effective means for detecting information from data to which image format information such as MPEG or JPEG data is added. Further, the present invention provides a digital watermarking technique capable of detecting embedded information efficiently without causing an increase in detection time or hardware size while enabling information detection from a large number of image formats. I will provide a.
[0017]
According to a first aspect of the present invention, a method of detecting digital watermark information for detecting information embedded as a digital watermark from content extracts format information of the content from the content, and detects a content detection target based on the format information. And a second step of trying to detect information from the extracted image area.
[0018]
Further, a plurality of image areas are determined in advance, and if information cannot be detected from the image area extracted based on the format information, a new area including a part or the whole of the image area in the first step is set. Or a third step of extracting an image area other than the image area in the first step and detecting the information again.
[0019]
Examples of the extraction of the image area include cutting out (trimming) of a partial area on an image plane in which pixel values (luminance values, color differences, RGB values, etc.) are expressed, or frequency space (frequency components, DCT coefficients, wavelet coefficients, etc.). ) Extraction of a specific frequency component. In addition, extraction of a field image from a frame image, geometric conversion on an image plane, conversion on a frequency space, or a combination of the above plurality may be used.
[0020]
According to a second aspect of the present invention, a digital watermark information detecting method for detecting digital watermark information from content data includes a preliminary process of trying to detect information corresponding to at least one bit, and an information process in the preliminary process. This processing includes reading out all the watermark information when the detection is successful. The preliminary processing is characterized in that, based on the format information of the content data, the presence / absence of digital watermark information of the content data is determined for at least one type of image area extracted from the content data.
[0021]
However, in the present embodiment, it is not always necessary to divide the detection process into the preliminary process and the main process as described above. It is also possible to directly determine the bit value of the watermark information without performing.
[0022]
The preliminary processing and the main processing are performed at the time of reproducing and recording the content, at the time of confirming the copyright information, at the time of receiving or transmitting, and the like. The execution time may be changed according to other conditions.
[0023]
Further, according to the present invention, a method for detecting digital watermark information from content data, based on the format information of the content data, includes at least one type of image area extracted from the content data. The method includes the step of specifying bits of watermark information.
[0024]
Further, according to the present invention, a method for detecting digital watermark information from content data, based on the format information of the content data, includes at least one type of image area extracted from the content data. It is characterized by having a step of determining the presence or absence of digital watermark information and a step of specifying bits of the watermark information.
[0025]
Further, according to the present invention, a method for detecting digital watermark information from content data, based on the format information of the content data, includes at least one type of image area extracted from the content data. Determining the presence / absence of digital watermark information, holding the determination result of the presence / absence of the digital watermark information, and the information relating to the data deformation, and performing the watermarking based on the held determination result and the information relating to the data deformation. Identifying bits of information.
[0026]
Further, the method for detecting digital watermark information may include, based on the format information of the content data, at least one type of image area extracted from the content data, or a new area including a part or the whole of the image area. It is characterized in that the presence or absence of digital watermark information is determined for an image area other than the image area.
[0027]
Further, the method for detecting digital watermark information may include, based on the format information of the content data, at least one type of image area extracted from the content data, or a new area including a part or the whole of the image area. A determination value is calculated from the content data for an image region other than the image region, and the presence or absence of digital watermark information is determined based on the determination value.
[0028]
Further, the method for detecting digital watermark information includes, when the determination value in at least one type of image area extracted from the content data satisfies a predetermined condition based on the format information of the content data, A new determination value is calculated for a new area including a part or the entirety of the above or an image area other than the image area, and it is determined whether or not there is digital watermark information based on the determination value. Features.
[0029]
Further, the method for detecting digital watermark information includes, when the determination value in at least one type of image area extracted from the content data satisfies a predetermined condition based on the format information of the content data, A determination value is calculated from the content data in accordance with an order in which at least one type of image area is likely to be assumed, and the presence or absence of digital watermark information is determined based on the determination value. I do.
[0030]
Further, the method of detecting digital watermark information is based on the determination value in accordance with a predetermined condition that is satisfied by the determination value in at least one type of image area extracted from the content data based on the format information of the content data. Determining whether or not there is digital watermark information, or newly calculating a determination value for a new area including a part or the entirety of the image area, or for an image area other than the image area, and determining the determination value. Is determined based on the content data, or a determination value is calculated from the content data in accordance with an order in which at least one type of image area which is likely to be assumed in the content data is prioritized. It is characterized in that it has a processing content of determining whether or not there is digital watermark information based on a value.
[0031]
Further, according to the present invention, a digital watermark information detecting device for detecting digital watermark information from the content data is provided for detecting at least one type of image area extracted from the content data based on the format information of the content data. A presence / absence determination processing unit that determines the presence / absence of digital watermark information, a presence / absence determination holding unit that stores the determination result of the presence / absence of the digital watermark information, and information related to the data deformation, and a data deformation information holding unit; And a bit specification processing unit for specifying the bits of the watermark information based on the determination result and the information on the data deformation.
[0032]
Further, the digital watermark information detecting device has a display device for displaying the result of the determination of the presence or absence of the digital watermark information by the presence / absence determination processing unit and the watermark information specified by the bit specification processing unit. .
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described. In the present embodiment, a known watermark detection and watermark reading algorithm is mainly used for image data in which the above-described statistical watermark is embedded and image data in which a watermark is embedded on MPEG DCT coefficients. The image data described below refers to, for example, frame data constituting a still image or a moving image.
[0034]
FIG. 1 is a diagram for explaining the principle of the watermark detection processing according to the present embodiment.
[0035]
As shown in FIG. 1, a digital watermark embedding device 102 embeds watermark information into image data 101 having various types of image formats, and generates watermarked image data 103. In the information embedding by the embedding device 102, the size of the above-described pixel block (watermark block) to be embedded depends on the target image format (the number of pixels of the image, progressive / interlace, etc.) and the watermark pattern to be detected. The shape may be changed. A watermark block 108 on the watermark image data 103 schematically shows a watermark block superimposed on an image plane in which pixel values (such as a luminance value, a color difference, and an RGB value) are expressed. On the other hand, a watermark frequency region 109 shown beside the watermark image data 103 represents the above-described frequency component of the watermark block 108 on a general DCT coefficient in JPEG, MPEG, or the like.
[0036]
The generated watermarked image data 103 is subjected to image processing such as changing the number of pixels by the image processing device 104 as necessary.
[0037]
The watermarked image data 103 or the image-processed watermarked image data 103 'is distributed via a recording medium or a communication medium. The image data receiving device 105 receives the watermarked image data 103 via the medium.
[0038]
In the image data receiving apparatus 105, the image area extracting apparatus 106 extracts an image area from the image data based on the format information of the input image data, and transmits the extracted image area to the watermark detecting apparatus 107. For example, when the image data is compressed data such as JPEG or MPEG, the watermark frequency region on the DCT coefficient is extracted depending on the format of the input image data. The watermark detection processing device 107 receives the extracted image area data and performs a process of detecting watermark information. If the watermark information cannot be detected for the image area data, the image area extraction device 106 outputs a new area including a part or the entirety of the image area, or another image other than the image area. The region is extracted, and the watermark detection processing device 107 performs the watermark information detection process again. For example, when the image data is compressed data such as JPEG or MPEG, a frequency region including a part or the whole of the watermark frequency region on the extracted DCT coefficient, or another frequency region is extracted.
[0039]
FIG. 2 is a schematic configuration diagram of the image data receiving device 105 shown in FIG. As shown in FIG. 2, the image data receiving device 105 of the present embodiment includes a CPU 201, a ROM 202, an input device 203, an output device 204, a communication device 205, and a memory 206.
[0040]
The CPU 201 is a device that controls the operation of the entire image data receiving device 105. The memory 206 is a storage device for storing various processing programs and data such as image data for controlling the entire operation of the image data receiving device 105.
[0041]
The input device 203 is a device for inputting image data on a recording medium such as a DVD or a CD-ROM or on a communication medium such as a wired or wireless communication medium. The output device 204 is a device that performs video output of the received image data. If audio data is added to the image data, audio output is also performed. The communication device 205 is a device that performs communication and control with another processing device via a network such as the Internet or an intranet, or a dedicated signal line such as SCSI or RS422.
[0042]
The image data receiving apparatus 105 has a control processing unit 209 developed on a memory 206 as a circuit in which an image data receiving processing apparatus 208, an image area extracting apparatus 106, and a digital watermark detection processing apparatus 107 are mounted on an LSI chip. Have as a program. Further, the receiving apparatus has an image data storage area 207 in the memory 206 for storing the received image data and the extracted image area. Each of the processing devices 106, 107, and 208 may be realized by a program developed on the memory 206, similarly to the control processing 209.
[0043]
Each program (also called code) is executed by the CPU 201. Part or all of each program is transmitted from a portable storage medium that can be used by the image data receiving apparatus 105 or from another server to a network or a network that can be used by the image data receiving apparatus 105. May be introduced into the image data receiving apparatus 105 via a communication medium.
[0044]
The image data reception processing device 208 stores all or part of the image data received by the input device 203 in the image data storage area 207 in a processable state.
[0045]
The image area extracting device 106 extracts the format information of the image data from the image data expanded on the memory 206, and performs processing for extracting an image area from the image data based on the format information.
[0046]
The control processing unit 209 instructs device control inside the receiving device, instructs the output device 203 to display control content or display detection information, according to the content of the watermark information detected by the digital watermark detection processing device 107, A process of instructing an external device to perform device control via the communication device 205 is performed.
[0047]
As shown in FIG. 2, in this embodiment, when each processing unit and processing device of the image data receiving device 105 is developed as a program on the memory 206, in order to avoid external illegal program analysis, It may be stored in the tamper-resistant area.
[0048]
When the receiving device 105 is a device such as a PC on which a user can relatively easily install a program, image data is received by a receiving function using a general function of an OS and an application on the OS. Also in this case, it is assumed that the image data is accessed via each processing unit stored in the tamper-resistant area.
[0049]
FIG. 3 is a flowchart illustrating a processing procedure of the image data receiving apparatus 105 of the present embodiment.
[0050]
In step S301, the image data reception processing device 208 of the image data receiving device 105 receives all or part of the image data via the input device 203, and stores the image data in the memory 206 in the receiving device. It is stored in the storage area 207.
[0051]
In step S302, if the stored image data has been encrypted such as scrambled, the image data is decrypted using the decryption key received at the time of performing the authentication process with the transmission source of the image data. The reception processing device 208 decodes the image data and descrambles the image data.
[0052]
In step S303, the image area extraction device 106 performs determination processing of an image format such as the number of pixels and a data format on the image data decoded in step 302 to obtain format information.
[0053]
If data for the image format determination process or data relating to a standard based on the image data is described in a predetermined location of the image data such as a header, the determination is made by referring to the data.
[0054]
Further, when the format of the image data is given in advance to the specific format conversion processing device 106 as information on the standard, information on the format of the image data can be attached to the image data or referred to another storage location. If they are stored, refer to them.
[0055]
In step S304, the image area extracting device 106 extracts an image area from the image data based on the format information of the image data obtained in step S303, and stores the extracted image area in the image data storage area 207.
[0056]
Note that the extraction of the image region described here means, as described above, the extraction (trimming) of a partial region on an image plane in which pixel values (luminance values, color differences, RGB values, and the like) are expressed, and frequency space (frequency Component, DCT coefficient, wavelet coefficient, etc.). In addition, extraction of a field image from a frame image, geometric conversion on an image plane, conversion on a frequency space, or a combination of the above plurality may be used.
[0057]
In step S305, the digital watermark detection processing device 107 detects the watermark information in the image area extracted based on the format information of the image data and stored in the image data storage area 207.
[0058]
In this step, the format information of the input image data and the specific format for which the digital watermark has been successfully detected may be recorded in the memory.
[0059]
If the watermark information cannot be detected by the above detection processing, the process returns to step S306, and it is determined whether the image area extraction device 106 has performed the detection processing for all of the plurality of image area candidates.
[0060]
In step S306, the image area extraction device 106 checks the format information stored in step S304 and the image area candidates based on the format information, and attempts detection processing for all the image area candidates. If it is determined that the watermark information cannot be detected for the image data, the watermark detection of the image data is stopped,
If there is any other image data to be received in step S309, a receiving process is performed in step S301.
[0061]
In step S306, if the image area extraction device 106 determines that the detection processing has not been performed for all the image area candidates based on the format information, the process returns to step S304, and the image data obtained in step S302 or From the image area extracted in step S305, an image area other than the image area based on the image format is extracted, and the extracted image area is stored in the image data storage area 207. In step S305, digital watermark detection is performed. The processing device 107 performs the watermark information detection process on the image area again.
[0062]
If watermark information is detected from the extracted image area in step S305, the watermark information is read by the digital watermark detection processing device 107 in step S307, and information related to device control and a sender of the image data are read from the detected information. Read the ID etc.
[0063]
In step S308, the control processing unit 209 instructs device control inside the receiving device, instructs the output device 203 to display control contents or detection information, or A process for instructing an external device to perform device control via the device 205 is performed. Further, the sender ID or the like of the read image data may be output to an external display device via the output device 204, or may be transmitted to an external device via the communication device 205.
[0064]
In step S309, it is checked whether reception of all the image data currently being received has been completed. If the reception of the image data has been completed, the reception process is stopped. The process returns to step S301 to continue the image data receiving process.
[0065]
Next, a second embodiment of the present invention will be described. This embodiment also targets image data in which a statistical watermark is embedded and image data in which a watermark is embedded on MPEG DCT coefficients.
[0066]
The second embodiment is different from the first embodiment in that the watermark detection is divided into a preliminary process and a main process. In the preliminary processing, an attempt is made to detect information corresponding to at least one bit. Only when the information detection succeeds in the preliminary processing, that is, when it is determined that there is a watermark, the process proceeds to this processing, and all the watermark information is read.
[0067]
FIG. 4 is a diagram illustrating a functional configuration of a digital watermark detection device or a digital watermark detection unit according to the present embodiment.
[0068]
The digital watermark detection device includes an input / output 401, a preliminary processing unit 403, a main processing unit 407, a storage unit 408, and a control unit 402 for controlling these units in a comprehensive manner. The above configuration is embodied as a process on the information processing apparatus by the CPU executing the data and the program loaded into the memory on the computer. In this case, a memory or an external storage device is used to store the processing units, the operation rules, and the reference data at the time of executing the rules. Further, the processing units, the operation rules, and the reference data at the time of executing the rules need not always be loaded into the memory, and can be realized by a hardware configuration such as an electronic circuit. This configuration may be incorporated as part of a DVD player, DVD recorder, or other broadcast receiver (set-top box) or the like.
[0069]
In addition, a part or all of each program is transmitted from a portable storage medium that can be used by the digital watermark detection device or from another server to a network or communication that can be used by the digital watermark detection device. It may be introduced into a digital watermark detection device via a medium.
[0070]
The storage unit 408 includes an image storage unit 409 that stores image data, a determination calculation rule storage unit 410 that stores calculation rules at the time of determination, and an image format and an image area based on the image format of the image data for which the presence or absence of a watermark is determined. An image area order holding unit 411 for storing the candidates and their priorities, a presence / absence determination threshold holding unit 412 for storing a threshold value for determining the presence / absence of a watermark based on a statistical value of image data, Presence / absence judgment result holding unit 413 that holds the result of the judgment, image region information holding unit 414 that stores image region information of image data when it is determined that there is a watermark, and watermark detection that stores an operation rule at the time of watermark detection An arithmetic rule storage unit 415, an information bit value determination threshold storage unit 416 that stores a threshold for determining the information bit value of the watermark, Having a detection information storage unit 417 for storing information bit values, however, the.
[0071]
The preliminary processing unit 403 includes a watermark presence / absence determination processing unit 404 that determines the presence / absence of a watermark on image data stored in the image storage unit 409 in accordance with the deformation pattern order stored in the deformation pattern order storage unit 410. An image area determination processing unit 405 that determines an image area having a watermark based on the presence / absence determination and performs processing for storing the image area information in the image area information holding unit 414.
[0072]
The processing unit 407 performs a process of detecting a watermark information bit value from an image region extracted based on the image region information stored in the image region information holding unit 414, and stores the watermark information in the detection information holding unit 417. And a watermark information determination processing unit 406.
[0073]
FIG. 5 shows a flow of the preliminary processing of the watermark information detection performed by the preliminary processing unit 403 having the above configuration.
[0074]
When image data is newly stored in the image holding unit 409 via the input / output 401 (step S1001), the control unit 402 instructs the preliminary processing unit 403 to determine whether or not the newly stored image data has a watermark. .
[0075]
In response, the watermark presence / absence determination processing unit 404 reads out the newly stored image data from the image holding unit 409 and reads out the calculation rule for determining the presence or absence of the watermark from the determination calculation rule storage unit 410 (step S1002). ).
[0076]
The calculation rule is a mathematical expression for statistically processing values related to pixels in the image data in order to determine whether or not the target image data has an artificial operation, that is, whether or not there is a watermark. This formula can be applied to various deformed images by taking in the type of the deformed pattern and the deformed pattern added to the image as parameters. The presence or absence of a watermark can be determined based on the result of this equation (determination operation value).
[0077]
In accordance with an instruction from the control unit 402, the watermark presence / absence determination processing unit 404 reads out image format information from the image holding unit 409 and reads out specific image area information based on the image format from the image area order holding unit 411. The image area order holding unit 411 holds a plurality of pieces of image area information based on image format information in advance, and each image area information is given a priority. The watermark presence / absence determination processing unit 404 determines whether readable image area information is stored in the image area order holding unit 411 (step S1003). If readable, the image stored in the image area order holding unit 411 is determined. The image area information having the highest priority with respect to the area information and its priority is read, and the read image area information and its priority are deleted or made unreadable to the image area order holding unit 411, and the image is read. A process for updating the order of the area information is performed (step S1005).
[0078]
The watermark presence / absence determination processing unit 404 extracts an image region from the image data based on the image region information, and performs the presence / absence determination operation on the extracted image region according to the determination calculation rule (step S1006). .
[0079]
The watermark presence / absence determination processing unit 404 compares the operation value of the determination operation for the image region with the presence / absence determination threshold value read from the presence / absence determination threshold value holding unit 412, and determines the presence / absence of a watermark of the image data in the image region. (Step S1007).
[0080]
That is, when the above-described determination operation value is equal to or smaller than the threshold value, that is, when “determination operation value ≦ threshold value”, the watermark presence / absence determination processing unit 404 first sends the image region order holding unit 411 It is determined whether readable image area information is stored (step S1003). If possible, the highest priority image area information among the readable image area information is newly read out, and For the image data.
[0081]
Further, when “determination operation value ≦ threshold value” and readable image region information is not stored in the image region order holding unit 411, that is, the image region information is stored in the image region order holding unit 411. If all or a plurality of determination operation values of the image area information are equal to or smaller than the threshold value, the watermark presence / absence determination processing unit 404 determines that the image data is “no watermark”, and determines the determination information as a watermark presence / absence. The result is transmitted to the determination result holding unit 413. In response to this, the presence / absence determination result holding unit 413 stores the determination information and transmits the determination information to the input / output unit 401. (Step S1004).
[0082]
On the other hand, in step S1007, if the determination operation value is larger than the threshold value, that is, “determination operation value> threshold value”, the watermark presence / absence determination processing unit 404 determines that the image data has “watermark presence”. And transmits the determination information to the presence / absence determination result holding unit 413. Also, the number of successes for the corresponding image area information in the deformation pattern order holding unit 411 is updated, and the priority is updated in the order of the number of successes. The presence / absence determination result holding unit 113 stores the determination information and transmits the determination information to the input / output unit 401.
[0083]
Further, the watermark presence / absence determination processing unit 404 transmits the image area information to the image area determination processing unit 405. The image area processing unit 405 that has received the image area information stores the image area information in the image area information holding unit 414 (step S1008).
[0084]
FIG. 6 shows a flow of the main processing of the watermark information detection performed by the main processing unit 407 having the above configuration.
[0085]
It is not necessary to divide the preliminary processing and the main processing, and it is also possible to use one processing unit.
[0086]
However, the image data handled by this processing unit does not necessarily have to be the same as the image data used in the preliminary processing, and may be different image data. In addition, the present process does not necessarily need to be performed after the preliminary process on the image data. A method is also possible in which after the preliminary processing is performed on a plurality of images collectively, the main processing is performed collectively.
[0087]
When the control unit 402 confirms that the image area information has been newly stored in the image area information holding unit 414, the control unit 402 instructs the main processing unit 407 based on the image data stored in the image holding unit 409 based on the image area information. An image area is extracted, and an instruction is issued to detect watermark information (step S2001).
[0088]
In response, the watermark information determination processing unit 406 reads out the newly stored image data from the image storage unit 409 and reads out the operation rule of the watermark information determination from the watermark detection operation rule storage unit 415 (step S2002).
[0089]
The watermark information determination processing unit 406 reads out the image area information newly stored in the image area information holding unit 414, extracts an image area from the image data based on the image area information, and applies watermark information to the image area. Is performed. That is, according to the watermark information determination calculation rule, the watermark information determination processing unit 406 calculates a determination calculation value corresponding to each information bit value from the image area (step S2003).
[0090]
The watermark information determination processing unit 406 compares the determination operation value of each information bit value calculated in step S2003 with the bit value determination threshold value read from the information bit value determination threshold value storage unit 416, and determines each information bit value. After the determination, the detection information is stored in the detection information holding unit 417. That is, a process of detecting and storing watermark information from the image area is performed (step S2004).
[0091]
The watermark information stored in the detection information holding unit 417 is transmitted to an external receiving terminal or a control device or another control unit in the device via the input / output unit 401. Control such as recording and reproduction is performed using the watermark information.
[0092]
According to the present embodiment, it is possible to reduce the amount of processing and the processing time required for determining a deformation pattern of image data when detecting a watermark. That is, by performing the preliminary processing with priority given to the image area depending on the image format, the processing amount can be reduced as compared with the conventional watermark detection processing.
[0093]
Also, in the preliminary processing steps S1005, S1006, and S1007 of the present embodiment, it has been described that the image area information with the highest priority is read from the image area order holding unit 411, and the determination operation value in the image area is compared with the threshold value. However, the image area information to be read may be a plurality of pieces of image area information with high priority. For example, in steps S1006 and S1007, determination calculation values in a plurality of image areas are calculated, and each determination calculation value is compared with a threshold. In the above process, there is a possibility that the plurality of calculated values may exceed the threshold. In such a case, in step S1008, the plurality of calculated values are stored in the image area information holding unit 414 corresponding to the plurality of calculated values, Eventually, this processing can cope with the processing for specifying the image area. Alternatively, a process of selecting the largest judgment operation value from the plurality of judgment operation values and holding the largest in the image area information holding unit 414 corresponding to the judgment operation value is also possible.
[0094]
Further, when the content is moving image data composed of a plurality of continuous image data (frame data), and a plurality of determination operation values exceed a threshold value as a result of performing the preliminary processing on certain frame data, An image area that is the same as or closer to the determination result of the most recent frame is referred to by referring to the determination result of the frame data that is closest to the frame data (for example, if the frame is the Nth frame, the (N−1) th frame data). May be determined as the image area of the frame data.
[0095]
Further, in the preliminary processing step S1007 of this embodiment, the determination processing of the determination operation value using one threshold value has been described, but the determination processing using a plurality of threshold values is also possible. For example, when the processing of the determination operation value C is determined by two threshold values T1 and T2 (T1 <T2), if C> T2, it is determined that the image area has “watermark” and the image area is determined. The information is stored in the image area information holding unit 414, and in this process, the watermark information bit is determined using the image area.
[0096]
On the other hand, if T1 <C ≦ T2, a new determination operation value C ′ may be calculated for a plurality of image areas close to the image area, and an image area satisfying C ′> T2 may be specified. In the above processing, when a plurality of pieces of high-priority image area information are read from the image area area order holding unit 411 in step S1005, there is a possibility that there are a plurality of determination operation values C that satisfy the condition based on the threshold. In such a case, image area information corresponding to a plurality of determination operation values is stored in the image area information holding unit 414, and finally, processing for specifying a deformation pattern in this processing can be dealt with.
[0097]
In the above embodiment, image data is described as an example of target content, but the present invention is not limited to this. For example, a processing method of judging the presence / absence of a watermark or detecting watermark information by giving priority to a specific area of music data is also possible.
[0098]
According to the above embodiment, it is possible to reduce the amount of processing required for watermark detection or to shorten the processing time.
[0099]
This makes it possible to construct a practical digital watermarking system for protecting the copyright of the content.
[0100]
【The invention's effect】
According to the present invention, the efficiency in the watermark detection processing is improved.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating distribution of image data.
FIG. 2 is a diagram illustrating a schematic configuration of an image data receiving apparatus 105 according to the first embodiment.
FIG. 3 is a flowchart illustrating a processing procedure for detecting watermark information according to the first embodiment;
FIG. 4 is a diagram illustrating a functional configuration of a digital watermark detection device according to a second embodiment.
FIG. 5 is a diagram showing a flow of preliminary processing in watermark information detection in the second embodiment.
FIG. 6 is a diagram illustrating a flow of a main process in detecting watermark information according to a second embodiment.
[Explanation of symbols]
101: Image data, 102: Digital watermark embedding device, 103: Watermarked image data, 104: Image processing device, 105: Image data receiving device, 106: Image area extraction unit, 107: Digital watermark detection processing unit, 108: Watermark Block 109: watermark frequency domain.

Claims (14)

A method of detecting digital watermark information for detecting information inserted as a digital watermark from content,
A first step of acquiring format information of the content with respect to the content, and extracting a detection target area of the content based on the format information;
A second step of detecting information from the area of the extracted content. 2. The method for detecting digital watermark information according to claim 1, wherein
A plurality of the detection areas are determined based on format information obtained from the content in advance,
And a third step of extracting a detection area other than the detection area in the first step and detecting the information again when information cannot be detected from the area of the extracted content. The method for detecting digital watermark information according to claim 2, wherein
Priorities are set for the plurality of detection areas based on the format information acquired in advance from the content, and the first and second steps are repeated according to the priorities until the information is successfully detected. 4. The method for detecting digital watermark information according to claim 3, wherein
In the second step, the number of successful information detections for the detection area is recorded, and the priority of the plurality of detection areas based on the format information of the content is updated according to the number of successful information detections. An electronic watermark information detection device for detecting information inserted as an electronic watermark from content,
Means for acquiring format information of the content for the content, and extracting an area to be detected for the content based on the format information;
Means for detecting information from the region of the extracted content. A program that causes a computer to operate as a digital watermark information detection device that detects information from content inserted as a digital watermark,
A code for realizing a first step of acquiring format information of the content with respect to the content and extracting an area to be detected based on the format information;
And a code for implementing a second step of detecting information from the area of the extracted content. A method for detecting digital watermark information from content data, comprising:
A preliminary process of trying to detect information corresponding to at least one bit;
In the preliminary processing, when the information detection is successful, including the main processing of reading all the watermark information,
The preliminary processing obtains format information of the content with respect to the content data, extracts an area for which the content is to be detected based on the format information, and determines whether or not the detection area has digital watermark information. Is determined. A method for detecting digital watermark information according to claim 7, wherein:
The presence / absence of digital watermark information is determined by performing a determination operation on the detection area and based on the result. A method for detecting digital watermark information according to claim 8, wherein:
The watermark information is read out in the main processing using the parameters when it is determined that the digital watermark information is present in the preliminary processing. The method for detecting digital watermark information according to claim 8, wherein
In the preliminary processing, prepare a plurality of detection areas determined from the format information obtained from the content data,
When it is not determined that there is digital watermark information in a certain detection area, the determination calculation is performed again in another detection area. The method for detecting digital watermark information according to claim 10, wherein
Priorities are set in advance for the plurality of detection areas, and the determination calculation is repeated according to the priorities until information detection is successful. The method for detecting digital watermark information according to claim 11, wherein
The number of times that it is determined that there is digital watermark information in the detection area is recorded, and the priority of the plurality of detection areas is updated according to the number of times of determination. An electronic watermark information detecting device for detecting electronic watermark information from content data,
A preliminary processing device that attempts to detect information corresponding to at least one bit;
In the preliminary processing, when the information detection is successful, including the present processing device that reads out all the watermark information,
The preliminary processing device obtains format information of the content with respect to the content data, extracts an area for which the content is to be detected based on the format information, and generates a digital watermark information Determine the presence or absence. A program that causes a computer to operate as a digital watermark information detection device that detects digital watermark information from content data,
A preliminary process of trying to detect information corresponding to at least one bit;
In the preliminary processing, when the information detection is successful, the main processing of reading out all the watermark information, and a code for executing
The code for executing the preliminary processing obtains format information of the content with respect to the content data, extracts an area to be detected of the content based on the format information, , And a code for determining the presence or absence of digital watermark information.

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