KR100449303B1 - Apparatus and method for inserting watermark using client system - Google Patents

Abstract

The present invention relates to a watermark embedding apparatus and method using a client system capable of reducing traffic on a network by watermarking user identification information (ID) on multimedia image data transmitted from a server at a client side. The watermark embedding apparatus includes a client system and a server system for retrieving a first digital image from a database and transmitting the first digital image to a client system in response to a first digital image transfer request from the client system. Here, the client system receives the first digital image from the server system, selects an image of a portion of the first digital image in which the watermark is to be inserted, and selects egg (R), ground (G), ratio ( B) Create a second digital image by inserting watermark information into any of the components.

Description

Apparatus and method for watermark insertion using a client system {APPARATUS AND METHOD FOR INSERTING WATERMARK USING CLIENT SYSTEM}

The present invention relates to a watermark embedding apparatus, and more particularly, to a watermark embedding apparatus and method using a client system capable of reducing traffic on a network by watermarking user identification information (ID) on multimedia image data transmitted from a server at a client side. It is about.

With the rapid increase of Internet users, various multimedia services have been provided on the network. Moreover, with the continuous improvement of network transmission speed and information quality, it is possible for computers and communication services to replace conventional analog broadcasting services and paper-printed newspapers. In particular, with the spread of MP3 players, digital cameras, and video that can be attached to computers, the era of high-quality information service through the Internet has come, and this change has led to the development of multimedia products in cyberspace through electronic commerce. 'S trade was active. At the same time, copyright protection technology has been used to ensure that multimedia products are distributed only to legitimate users.

In general, measures to secure digital data trade include data encryption, digital watermarking, and hardware / software security systems. Data encryption uses a key and algorithm, such as a secret key algorithm or a public key algorithm, to scramble the data so that only the person with the encryption key can decrypt the encrypted data. Technology. To date, encryption has been a relatively secure method for delivering multimedia data over a network. However, once encrypted multimedia content has been decrypted by a legitimate user, it cannot be prevented from being illegally copied and distributed. This need led to the emergence of watermark technology that can be used to verify ownership in legal disputes over the ownership of multimedia content.

Basically, watermarking is a technique of inserting a copyright company's unique logo or certification information into a multimedia product for the purpose of authentication or copyright protection. Such technology can detect data forgery and alteration and identify the owner of the data. have. Since the size of the watermarked data is the same as that of the original data, the general user cannot know that the watermark is embedded in the content. When piracy and distribution issues arise, content providers can identify who owns multimedia content by extracting an authenticated watermark from the content.

Watermarking techniques can be classified into various types according to the type of media and the technique used to convert the data. In particular, the spatial transformation method and the frequency domain mapping method, ie, Discrete, are used depending on the data conversion method. Cosine Transform, time-frequency domain mapping method (that is, wavelet transform) and spread spectrum communication method, among which the most commonly used method is DCT method which is frequency domain method to be. The frequency domain method is a method of inserting a watermark by converting original data and watermark data into a frequency domain and manipulating coefficients in the frequency domain. The most commonly used transform in frequency domain mapping is a discrete cosine transform (DCT). Since the DCT method is easy to implement and widely used for multimedia compression and conversion, it is robust to data manipulation such as compression and filtering. While extraction of pseudo-random number (PRN) watermarks is easy in the DCT technique, it is difficult to remove watermark data because the conversion coefficients of the watermarks are spread throughout the frequency domain. In addition, whether a watermark exists in the original data is determined by a correlation coefficient during the watermark extraction process.

Conventionally, in the case of digital content services through a network such as the Internet, watermark insertion and extraction processes for copyright protection have been entirely performed on the server side. However, in reality, if the server side performs all the watermark insertion and extraction processes entirely, the amount of data transmission, i.e., the load of the watermark processing by the server when the client is connected to the server is large. Therefore, when network traffic and data processing capacity of the server are not supported, the rate of data transmission error increases, and the time that multimedia data such as image or audio data is transmitted to the client side is delayed, causing inconvenience to the user. Is generated. In other words, in a state where a few clients are connected to the server side, watermark processing and data transfer processing are performed on the server side without difficulty, but if the number of clients connected is too large, watermark insertion / There is a limitation of processing power to perform extraction processing and multimedia data transmission service together.

In addition, since only the copyright information of the work is inserted when the watermark is inserted on the server side, if any client distributes a copy of the work to a third party after data transmission is completed to the client side, the distributor's information is included in the work. It will not be inserted into the system, making it impossible to find an illegal distributor. Therefore, the copyright holder or the digital content provider cannot grasp the illegal distribution of the copied works by the distributor, and can not fundamentally prevent the distributor from illegal copying.

Accordingly, the present invention is to solve the above-described problems, watermark insertion apparatus using a client system that can reduce the traffic on the network by watermarking the user identification information (ID) in the multimedia image data transmitted from the server at the client side And to provide a method.

Another object of the present invention is to use a client system that separates R, G, and B components of an inserted portion of a watermark and applies watermarking to only one of the components, thereby minimizing image distortion. A watermark embedding apparatus and method are provided.

1 is a block diagram of a watermark insertion apparatus using a client system according to an embodiment of the present invention.

FIG. 2 is a block diagram conceptually showing the watermark insertion unit of FIG. 1; FIG.

3 is a diagram illustrating an internal algorithm of the watermark insertion unit of FIG. 1.

<Explanation of symbols for the main parts of the drawings>

A: Client system B: Server system

7: Watermark Insertion 9: Main Server

10: Database Manager 11: User Information Database

12: Image Database (DB) 13: Copyright Information Database (DB)

110: target data analysis unit 120: two-dimensional format unit

130: image watermark insertion unit

Watermark embedding apparatus using a client system according to the present invention for achieving the above object, the client system; And a server system for retrieving the first digital image from the database and transmitting the first digital image to the client system in response to the first digital image transfer request from the client system. Here, the client system receives the first digital image from the server system, selects an image of a portion where a watermark is to be inserted in the first digital image, and selects an egg (R), a paper ( G), Create a second digital image by inserting watermark information into any of the (B) components.

In addition, a watermark embedding method using a client system according to the present invention comprises the steps of: receiving a first digital image; Grid-coding the identification information of the user to generate a code to be inserted as a watermark; Determining a portion of the first digital image to insert a watermark; Dividing the watermark embedding into egg (R), paper (G), and non-B components; Selecting one component among the egg (R), the (G), and the (B) components; Dividing the watermark embedding portion composed of the selected components into blocks of 8 x 8 pixels; Converting the first digital image into a frequency component using Discrete Cosine Transform (DCT); Mixing the embedding code with the discrete cosine transformed first digital image to generate joint data; Inverse discrete cosine transform (IDCT) the combined data to generate a second digital image in which the user identification information is inserted as a watermark. Here, the embed code is inserted in the intermediate frequency region of the frequency components of the first digital image.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.

1 is a block diagram of a watermark embedding apparatus using a client system according to the present invention. As shown in Fig. 1, the watermark embedding apparatus according to the present invention is broadly divided into image data requested to the client system A by being connected through the client system A, the client system A, and the Internet 8; It consists of a server system (B) for transmitting the.

The client system (A) is a watermark inserting unit (7) for inserting user identification information (ID) as a watermark in the image data transmitted from the server system (B), and requests the image data transmission to the server system (B) side, At least one user terminal 5 for displaying the watermark-embedded image data through the web browser, and the watermark-embedded image data installed in the watermark embedding unit 7; And a recording medium 6 for storing.

The server system B receives the image data transfer request from the client system A side, withdraws the requested image data from the database DB, encrypts the extracted image data, and then stores the client through the Internet 8. It is provided with a main server 9 which transmits to the system A and is in charge of overall control to perform the role of extracting a watermark from the image data transmitted from the client system A. In addition, the server system (B) is connected to the main server (9), watermark extraction means 14 for extracting the watermark inserted in the image data, encryption means 15 for encrypting the image data, connected to various databases And integrated management of these, the database manager 10 for transmitting the requested data to the main server (9), the user information database (DB) 11, the image database (DB) 12 connected to the database manager 10 And a copyright information database (DB) 13.

The user information DB 11 stores member information such as personal information and member ID of an individual registered as a member in the server system B. Although not distinguished from the drawing, a consumer who receives image data including copyright information The member and the supplier member supplying the work to the server side can be stored separately. The image DB 12 stores various image data. Preferably, since the embodiment of the present invention implements an animation service through the Internet, the image DB 12 stores image data for animation, and each image data is stored in a copyright information DB ( It is stored so as to be mapped with 13) so that the main server 9 can recognize the copyright holder of each image data. The copyright information DB 13 is linked with the image DB 12 to store copyright holder information of each image data, that is, personal identification information of the copyright holder and information such as copyright holder ID.

Fig. 2 is a block diagram conceptually showing the watermark inserting unit 7 provided on the client system A side. The watermark inserting unit 7 receives text to be inserted into image data, that is, target data, that is, user identification information ID, and combines two different types of data to provide an image with a watermark embedded therein. To this end, the two-dimensional formatter 120 converts the input text, that is, user identification information ID, into a two-dimensional image format (hereinafter, text converted into the two-dimensional image format is referred to as a "text image"). In addition, the target data analysis unit 110 analyzes the target image input in various forms to determine the format, extracts only data representing the image purely without any additional information such as a header, and extracts the extracted data. It serves to provide the image watermark inserting unit 130 in the dimensional image format. The target data analyzer 110 provides the two-dimensional formatter 120 with information about the format of the target data (“target data format information”) such as an image size, a color mode, and a bit array structure of each pixel data. The two-dimensional format unit 120 provides the text image in the same two-dimensional image format as the data provided from the target data analyzer 110 to the image watermark inserting unit 130 by using the target data format information.

The image watermark inserting unit 130 inserts a text image, which is user ID information input from the two-dimensional format unit 120, into two-dimensional target data input from the target data analysis unit 110, and inserts a text watermark. Create

FIG. 3 shows an internal algorithm of the watermark inserting unit 7 of FIG. 1, which shows the watermarking process in more detail than the conceptual diagram of FIG. 2.

As shown in Fig. 3, when there is an image download request from the user terminal 5, the watermark inserting section 7 is the original image data that the user wants to download from the image DB 12 of the server system B. After downloading (step S10), the portion of the original image data to insert the watermark is determined (step S12). The image data, which is the watermark embedding portion extracted in the step S12, is separated into R (R), G (G), and B (B) components (step S14), and watermarking is performed from the separated R, G, and B components. One component to be applied is selected (step S16). Then, the selected image part is divided into blocks of 8 (pixel) X 8 (pixel) to be integer matrixed (step S18), and the original image is converted into frequency components using discrete cosine transform (DCT) (step S20). ).

On the other hand, the watermark embedding section 7 lattice codes the ID information of the connected user (step S22) to generate a code to be inserted as a watermark (step S24). Since the user identification information (ID) is a character string of about 8 bytes, it occupies a small portion of the image data having a relatively large amount of information, thereby obtaining a high speed. In addition, there is a code table corresponding to alphabetic spellings and numbers that can be used as the user identification information (ID), which is a lattice 8 code. The lattice 8 code selects all the possible ones at a constant distance from the origin and selects through the experiment the best extraction results. That is, each spelling of the user ID corresponds to one Lattice 8 code.

Here, the lattice coding will be described in more detail.

The lattice code is a vector code and is used to reconstruct the source vector by calculating the shortest distance from the source vector with the vector whose distortion is in the source vector. According to the known theory, 6, 8, and 16-dimensional vectors are known to have the best code values. In the embodiment of the present invention, since the code values of the 8-dimensional vectors are used, they are referred to as lattice 8 codes. Is possible. In the case of the image, after the DCT, the high frequency range has the most important information, so this part is 8-dimensional vector coded. If you insert and restore the image in this way, the human eye can recognize the pattern. In the embodiment of the present invention, since the data to be inserted is user identification information (ID), which is not character data, the insertion amount is very small compared to the image data, so that the data can be inserted quickly and can be easily inserted and inserted repeatedly. .

The 8-dimensional vector code used in the embodiment of the present invention is a certain distance from the origin vector, and generates all the elements consisting of only -1,0,1, and re-filters that the distance between them is more than a certain distance apart. Came out. The reason is that the source vectors are found by calculating the shortest distance from all the source vectors in the code table with the transform vectors, so all the vectors in the table need to be equally spaced apart. Among the vectors thus filtered, the code table used in the embodiment of the present invention needs only 36 codes because only the alphabet and the number used for the user ID need to correspond. The codes finally selected through the above-described process are shown in the character-to-lattice code correspondence table below.

const char CharMapTable [36] [2] = {

{'0', 0}, {'1', 1}, {'2', 2}, {'3', 3}, {'4', 4},

{'5', 5}, {'6', 6}, {'7', 7}, {'8', 8}, {'9', 9},

{'A', 10}, {'B', 11}, {'C', 12}, {'D', 13}, {'E', 14},

{'F', 15}, {'G', 16}, {'H', 17}, {'I', 18}, {'J', 19},

{'K', 20}, {'L', 21}, {'M', 22}, {'N', 23}, {'O', 24},

{'P', 25}, {'Q', 26}, {'R', 27}, {'S', 28}, {'T', 29},

{'U', 30}, {'V', 31}, {'W', 32}, {'X', 33}, {'Y', 34},

{'Z', 35}

};

const long CharToLatticeMap [36] [8] = {

/ * 0 * / {1,1, -1, -1,1,1,1, -1},

/ * 1 * / {-1, -1,1,1, -1, -1, -1,1},

/ * 2 * / {1, -1,1,1,1, -1,1, -1}

/ * 3 * / {-1, -1, -1, -1, -1, -1, -1, -1},

/ * 4 * / {-1, -1, -1, -1,1, -1,1,1},

/ * 5 * / {-1, -1, -1,1, -1,1, -1,1},

/ * 6 * / {-1,1, -1, -1, -1,1,1, -1},

/ * 7 * / {1,1,1,1,1, -1,1,1},

/ * 8 * / {-1,1,1, -1,1, -1,1,1},

/ * 9 * / {1,1, -1,1, -1,1,1, -1},

/ * A * / {1, -1, -1, -1, -1, -1, -1, -1},

/ * B * / {1, -1, -1, -1, -1, -1,1,1},

/ * C * / {-1,1,1, -1,1,1, -1, -1},

/ * D * / {-1, -1, -1, -1,1, -1, -1, -1},

/ * E * / {1, -1,1, -1, -1, -1,1, -1},

/ * F * / {-1,1, -1, -1, -1, -1,1,1},

/ * G * / {1, -1, -1, -1,1,1, -1, -1},

/ * H * / {-1, -1,1,1, -1,1, -1, -1},

/ * J * / {1, -1,1,1, -1,1,1, -1},

/ * K * / {-1, -1, -1, -1,1,1, -1,1},

/ * L * / {-1, -1, -1, -1,1,1,1, -1},

/ * M * / {-1, -1,1,1,1,1, -1,1},

/ * N * / {-1,1,1,1,1, -1, -1, -1},

/ * O * / {-1,1, -1,1,1,1,1, -1},

/ * P * / {1, -1, -1, -1,1, -1,1, -1},

/ * Q * / {1,1, -1,1,1, -1, -1,1},

/ * R * / {-1,1, -1, -1, -1, -1, -1, -1},

/ * S * / {1,1,1, -1, -1, -1, -1, -1},

/ * T * / {1,1,1, -1,1, -1, -1,1},

/ * U * / {1,1,1, -1, -1, -1,1,1},

/ * V * / {-1,1,1,1, -1,1,1, -1},

/ * W * / {-1,1, -1,1,1, -1,1,1},

/ * X * / {1, -1,1, -1, -1,1, -1, -1},

/ * Y * / {1,1,1,1,1,1, -1,1},

/ * Z * / {-1, -1,1,1,1, -1,1,1},

};

The insertion data generated through the steps S22 and S24 as described above is mixed with the watermark embedded part image data DCT-converted in step S26 (step S26). In step S26, the code (i.e., insertion data) generated in step S24 is inserted into the intermediate frequency portion of the transformed 8 X 8 matrix, which is the watermark embedding portion. The reason why the intermediate frequency region is selected in the present embodiment is that a large amount of distortion occurs in the image when inserted into the high frequency region, and the preservation of the inserted data is much weakened when inserted into the low frequency region. In addition, the insertion data generated in step S24 is multiplied by a predetermined weight. If the weight is large, it is advantageous to restore the watermark later, but the insertion of watermark may damage the image. Since the watermark information may be difficult to recover even with a little noise, in this embodiment, the weight may be input from the user, or after inserting the watermark while changing the weight for the image, a good value is automatically obtained. The choice was made.

Subsequently, in step S26, inverse discrete cosine transform (IDCT) of the combined data having the watermark inserted therein (step S28), and the 8X8 blocks are reconstructed into images again, and the user identification information (ID) is converted into watermark information. The inserted watermarked final image is generated (step S30).

On the other hand, the watermark insertion unit 7 installed in the client system (A) is implemented as a software program, which can be downloaded by a plug-in method when the user logs in to the website for the image transmission service, In order to download an image, the dedicated program must be executed in advance.

Further, in the embodiment of the present invention, the image data transmitted from the server side to the client side is image data for animation, but the transmitted data may include both image or audio data as multimedia digital data.

As mentioned above, although preferred embodiment of this invention was described, those skilled in the art can change variously, without deviating from the claim of this invention.

As described above, according to the watermark embedding apparatus and method using the client system according to the present invention, when the client side wants to download image data from the server side, the server side inserts a watermark into the image data. It can be performed on the client side, reducing traffic on the network, and inserting only the user ID as a watermark, which reduces the insertion amount. Also, since the information inserted as the watermark is a user ID, the user's intention to copy illegally can be blocked. There is an additional effect.

That is, in the structure of performing the conventional watermarking insertion on the server side, when the watermark insertion processing and the data transmission processing are performed in the state where a plurality of clients are connected to the server side, it causes inconvenience to the user due to time delay. In the embodiment of the present invention, since watermark embedding is performed in each of the client systems connected to the server, this speed delay problem is solved, and real-time transmission and stable reception of an image are possible. Therefore, the information provider who operates the server system reduces the investment cost due to the expansion of the server, bringing the management profit.

In addition, the watermark embedding apparatus and method using the client system according to the present invention, separate the R, G, B components of the image of the insertion portion when the watermark is inserted to suit the color image, and applies watermarking to only one of them This not only improves speed but also minimizes image distortion.

Claims (6)

An apparatus for embedding a watermark in a digital image, Client systems, A server system for retrieving the first digital image from a database and transmitting it to the client system in response to a first digital image transfer request from the client system Including, The client system receives the first digital image from the server system, selects an image of a portion in which the watermark is to be inserted in the first digital image, and recognizes an egg (R) or a finger (G) of the selected partial image. And (b) generating a second digital image by embedding watermark information in any one of the non-B components. The method of claim 1, The client system, A watermark inserting unit for inserting user identification information into the first digital image as the watermark information; At least one user terminal for requesting the server system to transmit the first digital image and for displaying the second digital image through a web browser; A recording medium for storing the second digital image into which the watermark information is inserted Including, And the user identification information includes alphanumeric data. The method of claim 1, wherein the server system, A main server receiving a request for transmission of the first digital image from the client system, extracting the requested first digital image from an image database, and transmitting the first digital image to the client system; Encryption means for encrypting the first digital image before transmission to the client system, and And a watermark extracting means for extracting watermark information embedded in the second digital image. The method of claim 3, wherein the server system, The watermark further comprises a member information database storing a plurality of user information registered as members in the server system, and a copyright information database storing copyright information of the first digital image in association with the member information database. Insert device. The method of claim 2, The watermark inserting unit, Converting the first digital image into a predetermined two-dimensional image format, converting the user identification information into the preset two-dimensional image format, and converting the converted user identification information into the converted first digital image. And inserting the converted user identification information into an intermediate frequency region among a high frequency region, an intermediate frequency region, and a low frequency region of the converted first digital image. In the method for embedding a watermark using a client system, Receiving a first digital image, Generating a code to grid-code the identification information of the user to insert as a watermark; Determining a portion of the first digital image to insert a watermark; Separating the watermark embedding into egg (R), paper (G) and non-B components; Selecting one component among the R, G, and B components, and Dividing the watermark embedding portion composed of the selected components into blocks of 8 x 8 pixels; Converting the first digital image into a frequency component using Discrete Cosine Transform (DCT), Mixing the embedding code with the discrete cosine transformed first digital image to generate joint data; Inverse Discrete Cosine Transformation (IDCT) on the combined data to generate a second digital image in which the user identification information is inserted as a watermark. Including, And the embedding code is inserted in an intermediate frequency region of frequency components of the first digital image.