JP4187916B2 - Digital watermark embedding device and detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital watermark system that embeds information such as copyright for preventing illegal copying of digital works such as images and sounds as a so-called digital watermark, and some data such as images and sounds are cut off and missing. The present invention also relates to a digital watermark embedding device and a detection device that can extract embedded copyright information from the missing data.
[0002]
[Prior art]
In recent years, in order to protect the copyright of multimedia data such as images and sound (usually composed of digital data), information related to copyright has been embedded in the data as so-called digital watermarking. ing. When illegal copying of data is performed, the location of the copyright of the data can be clarified by the digital watermark.
[0003]
In communication and broadcasting, copyright information is embedded as a digital watermark on the transmission side. There are roughly two methods of embedding digital watermarks in image data on the transmission side. One method is a method of directly embedding a digital watermark in data by changing the value of pixel data. The other method is to change the coefficient value after DCT (Discrete Cosine Transform), wavelet transform (Wavelet Transform) conversion, etc., and embed a digital watermark, and perform inverse conversion. This is a method for generating pixel data in which a watermark is embedded.
Each of the above systems is described in the document “Basics of Digital Watermarking” (written by Kokoo Matsui, published by Morikita Publishing in August 1998).
[0004]
[Problems to be solved by the invention]
However, in the conventional digital watermark system, when a part of the screen data is cut out and missing, the reference position for embedding the digital watermark and the reference position of the block for performing DCT or wavelet transform are unknown. There was a problem of becoming. As a countermeasure, in the method based on the “digital watermark embedding device for an image” (Japanese Patent Application No. 11-297334) according to the applicant's application, a part of the block reference position confirmation mark is embedded, and the part is not cut off. This makes it possible to detect digital watermarks from existing images.
[0005]
Therefore, by using the method according to this patent application, even when a part of the screen is cut out and missing, the reference position of the block can be detected and the digital watermark can be detected.
[0006]
However, conventional digital watermark embedding methods have a problem that marks cannot be detected when image processing such as MPEG2 compression is performed because the digital watermark is embedded only in a part of the image.
[0007]
An object of the present invention is to detect a digital watermark from missing data even if a part of the image or sound is cut out and missing in a digital watermark system in which copyright information is embedded in data such as image or voice. Therefore, it is possible to provide a digital watermark embedding device and a detection device that can extract information on normal copyright.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the digital watermark embedding device of the present invention is a digital watermark embedding device that embeds digital watermark information in an original image signal, and embeds a first random number sequence in the original image information; The original image information in which the first random number series is embedded includes means for embedding the second random number series by shifting the embedding position in accordance with the copyright information .
[0009]
According to another aspect of the present invention, there is provided a digital watermark detection apparatus for detecting information of a digital watermark embedded by the digital watermark embedding apparatus according to claim 1, wherein the second digital watermark is embedded in accordance with the copyright information. Means for detecting a random number sequence; means for detecting a first random number sequence embedded in the original information; and means for extracting information of the embedded digital watermark from a shift in the embedded position of the two random number sequences These are provided .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on an embodiment of the invention with reference to the accompanying drawings.
FIG. 1 is a block diagram showing an embodiment of a digital watermark embedding apparatus according to the first aspect of the present invention.
In FIG. 1, 1 is a digital watermark embedding circuit for copyright, and 2 is a digital watermark embedding circuit for positioning.
[0013]
The operation will be described.
In FIG. 1, an original image signal (baseband signal) in which a digital watermark is embedded and copyright information are input to the digital watermark embedding circuit 1 for copyright as shown in the figure, and the copyright information is embedded. An image signal (hereinafter referred to as a copyrighted image signal) is output. The copyrighted image signal is sent to the positioning digital watermark embedding circuit 2, which embeds the positioning digital watermark that determines where the copyright information is embedded on the screen, and contains the copyright and position information. Output image signal. Image signals with copyright / position information are distributed through broadcasting and the Internet.
In this embodiment, the digital watermark is embedded in the order of the digital watermark for copyright and the digital watermark for positioning, but can be embedded in the reverse order.
[0014]
As the copyright digital watermark embedding circuit 1, a circuit using an arbitrary method can be used as a copyright digital watermark embedding method. As an example, it is possible to use a circuit using a method based on the above-mentioned “digital watermark embedding apparatus for images” (Japanese Patent Application No. 11-297334) according to the above-mentioned application of the present applicant. In this method, an input image is divided into blocks having a size of m × n (m and n are integers of 1 or more), and a block code corresponding to copyright information is embedded in each block.
[0015]
FIG. 2 is a block diagram showing an embodiment of the digital watermark detection apparatus according to the first invention of the present invention.
In FIG. 2, 3 is a copyright digital watermark detection circuit, and 4 is a positioning digital watermark detection circuit.
[0016]
The operation will be described.
In FIG. 2, an image signal containing copyright / position information distributed from the digital watermark embedding side through broadcast or the Internet is input to the copyright digital watermark detection circuit 3 and also input to the positioning digital watermark detection circuit 4. Then, the positioning digital watermark detection circuit detects a reference position for determining the position where the copyright information is embedded on the screen, and outputs this as a position information signal.
[0017]
The copyright digital watermark detection circuit 3 uses the reference position indicated by the position information signal sent from the positioning digital watermark detection circuit 4 for the input image signal containing the copyright / position information. The digital watermark for copyright is detected in this, and copyright information is extracted based on this.
In the above description, the embedded copyright information can be extracted from the image signal with copyright / position information output from the embedding side of the digital watermark even if a part of the image signal is cut out and missing.
[0018]
FIG. 3 is a block diagram showing a configuration example of the positioning digital watermark embedding circuit 2 in FIG.
In FIG. 3, 5 is an embedding filter circuit, 6 is a random number sequence multiplying circuit, 7 is a random number sequence generating circuit, and 8 is a random number sequence embedding circuit.
[0019]
The operation will be described.
In FIG. 3, the copyrighted image signal output from the copyright digital watermark embedding circuit 1 (see FIG. 1) is branched into two, and one of them is input to the embedding filter circuit 5. The characteristics of the filter circuit 5 can be arbitrarily set by a person who embeds the positioning digital watermark. The filter image signal for embedding subjected to the filter processing in the filter circuit 5 is sent to the random number series multiplication circuit 6. The random number sequence multiplication circuit 6 multiplies the embedding filter image signal by the random number sequence signal generated by the random number sequence generation circuit 7.
[0020]
The random number sequence generation circuit 7 generates a random number sequence signal having a size for one frame. Each element of the random number sequence signal takes 1 or −1, and the average value of the values taken by each element is 0. The random number series multiplication circuit 6 outputs a result of multiplication of the random number series signal and the above-described embedding filter image signal as an embedding random image signal. The random number sequence embedding circuit 8 embeds position information by adding the embedding random image signal sent from the random number sequence multiplying circuit 6 to the other bifurcated image signal containing the copyright, thereby obtaining the copyright / position Output as an image signal with information.
[0021]
FIG. 4 is a block diagram showing a configuration example of the positioning digital watermark detection circuit 4 in FIG.
In FIG. 4, 9 is a filter circuit for detection, 10 is a random number sequence multiplication circuit, 11 is a random number sequence generation circuit, 12 is a positioning control circuit, 13 is a random number sequence position control circuit, and 14 is a random number sequence positioning circuit.
[0022]
The operation will be described.
In FIG. 4, the image signal with copyright / position information output from the digital watermark embedding side is input to the filter circuit 9 for detection. The characteristics of the detection filter circuit 9 can be arbitrarily set by a person who detects the positioning digital watermark. The filter image signal for detection subjected to the filter processing in the filter circuit for detection 9 is sent to the random number series multiplication circuit 10. The random number sequence multiplication circuit 10 multiplies the filter image signal for detection by the position-shifted random number sequence generated by the random number sequence position control circuit 13 described below.
[0023]
The random number sequence generation circuit 11 generates a random number sequence signal having the same size as one frame as the random number sequence signal generated on the digital watermark embedding side. The positioning control circuit 12 sequentially generates two integers i (horizontal direction) and j (vertical direction) in order to shift the position of the random number sequence signal generated by the random number sequence generation circuit 11, and generates the positioning control signal ( i, j). The random number sequence position control circuit 13 determines the position of the random number sequence signal generated by the random number sequence generation circuit 11 as i pixels in the horizontal direction and j pixels in the vertical direction according to the positioning control signal (i, j) from the positioning control circuit 12. The position is shifted and the position is shifted and output as a random number series. The random number series multiplication circuit 10 outputs a multiplication result of the position-shifted random number series and the above-described detection filter image signal as a detection random number image signal.
[0024]
The output detection random number image signal is sent to the random number sequence positioning circuit 14 to calculate the sum of the elements of the detection random number image signal. Specifically, the positioning control signal (i, j) from the positioning control circuit 12 is fetched, and the sum of the elements of the random number image signal for detection is obtained for all combinations of the positioning control signals (i, j), The positioning control signal (i, j) when the maximum sum appears is output as a position information signal.
That is, in this method, the same random number sequence as that of the embedded detection random number image signal (random number sequence) is generated while shifting the position, and the correlation between the generated random number sequence and the embedded random number sequence is The maximum position is detected.
[0025]
Next, the electronic watermark according to the second invention of the present invention, in which two types of random number sequences are embedded with their positions shifted, and information such as copyright can be detected from the positional relationship between the two types of embedded random number sequences. An embedding device and a detection device will be described.
[0026]
First, a digital watermark embedding device will be described.
FIG. 5 is a block diagram showing an embodiment of a digital watermark embedding apparatus according to the second invention of the present invention.
In FIG. 5, 15 is a random number A embedding circuit, 16 is a random number B embedding circuit, and 17 is an embedding position control circuit.
[0027]
The operation will be described.
In FIG. 5, an original image signal in which a digital watermark is embedded is input to the random number A embedding circuit 15 and an image signal with random number A is output.
Here, the circuit configuration of the random number A embedding circuit 15 is the same as the circuit configuration of the positioning digital watermark embedding circuit described with reference to FIG. 3 (the circuit portion indicated by reference numeral 2 in FIG. 1). , Not copyrighted) is input, and a random number sequence signal generated in advance by a circuit corresponding to the random number sequence generation circuit 7 (see FIG. 3) is embedded and output as an image signal with random number A.
[0028]
The output random number A-containing image signal is sent to the random number B embedding circuit 16, in which a random number B different from the random number A is generated in advance, and the embedding position is determined as an embedding position control circuit described next. In accordance with an embedding position control signal (i, j) sent from 17, a random number sequence signal shifted by i pixels in the horizontal direction and j pixels in the vertical direction and shifted in position is embedded in the image signal with random number A that is the input of the circuit. , And output as an image signal with random numbers AB.
[0029]
In the above, the embedding position control circuit 17 uses the two integers i (horizontal direction) and j (vertical direction) for shifting the position of the random number B in accordance with the copyright information input to the circuit as an embedding position control signal. The data is output to the B embedding circuit 16. For example, when a numerical value of 0 to 255 is embedded as 8-bit copyright information, the quotient when the numerical value is divided by 16 is output as i, and the remainder is output as j.
[0030]
Next, a digital watermark detection apparatus will be described.
FIG. 6 is a block diagram showing an embodiment of the digital watermark detection apparatus according to the second aspect of the present invention.
In FIG. 6, 18 is a random number A detection circuit, 19 is a random number B detection circuit, and 20 is an information decoding circuit.
[0031]
The operation will be described.
In FIG. 6, the random number AB-containing image signal output from the digital watermark embedding side is input to the random number A detection circuit 18 and the random number B detection circuit 19. The circuit configurations of the random number A detection circuit 18 and the random number B detection circuit 19 are the same as those of the positioning digital watermark detection circuit described in FIG. 4 (the circuit portion indicated by reference numeral 4 in FIG. 2). The random number A detection circuit 18 outputs position information detected by the circuit as random number A position information, and the random number B detection circuit 19 outputs position information detected by the circuit as random number B position information.
[0032]
Both pieces of the position information are sent to the information decoding circuit 20, where the positional deviation between the random number A position information and the random number B position information is converted into embedded watermark information and output as copyright information.
Also in the above (detection of digital watermark according to the second invention of the present invention), the image signal with copyright / position information output from the embedded side of the digital watermark is embedded even if part of it is cut off and missing. Copyright information can be extracted.
[0033]
【The invention's effect】
According to the present invention, by embedding a random number sequence in an image signal on the embedding side and detecting the random number sequence on the detecting side, even when a part of the image is cut out and missing, the copyright or the like is embedded. Information can be extracted.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a digital watermark embedding apparatus according to a first invention of the present invention.
FIG. 2 is a block diagram showing an embodiment of a digital watermark detection apparatus according to the first invention of the present invention.
FIG. 3 is a block diagram showing a configuration example of the positioning digital watermark embedding circuit in FIG. 1;
FIG. 4 is a block diagram showing a configuration example of a positioning digital watermark detection circuit in FIG. 2;
FIG. 5 is a block diagram showing an embodiment of a digital watermark embedding apparatus according to a second invention of the present invention.
FIG. 6 is a block diagram showing an embodiment of a digital watermark detection apparatus according to the second invention of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Digital watermark embedding circuit for copyright 2 Digital watermark embedding circuit for positioning 3 Digital watermark detection circuit for copyright 4 Digital watermark detection circuit for positioning 5 Embedding filter circuit 6 Random number sequence multiplication circuit 7 Random number sequence generation circuit 8 Random number sequence embedding circuit DESCRIPTION OF SYMBOLS 9 Detection filter circuit 10 Random number series multiplication circuit 11 Random number sequence generation circuit 12 Positioning control circuit 13 Random number sequence position control circuit 14 Random number sequence positioning circuit 15 Random number A embedding circuit 16 Random number B embedding circuit 17 Embedding position control circuit 18 Random number A detection circuit 19 random number B detection circuit 20 information decoding circuit

Claims (2)

An electronic watermark embedding device for embedding digital watermark information in an original image signal,
Means for embedding a first random number sequence in the original image information;
An electronic watermark embedding apparatus comprising: means for embedding a second random number sequence by shifting an embedding position in accordance with copyright information in original image information in which the first random number sequence is embedded . An electronic watermark detection apparatus for detecting information of an electronic watermark embedded by the electronic watermark embedding apparatus according to claim 1,
Means for detecting a second random number sequence embedded according to the copyright information;
Means for detecting a first random number sequence embedded in the original information;
Means for extracting information of the embedded digital watermark from a shift in the embedded position of the two random number sequences;
Digital watermark detection apparatus, characterized in that it comprises a.

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