KR100405827B1 - Method of inserting/extracting digital watermarks and apparatus for using thereof - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a watermarking technology for protecting the copyright of digital video contents. The present invention relates to a method of inserting and extracting a watermark that can be used as a watermark, such as a logo that can visually identify a watermark when the watermark is inserted and extracted. And a device using the same.

Conventionally, a watermark is detected by using a correlation between a watermark included in an image signal and a watermark separately generated in order to use a pseudo random number generated by using a unique key or a user key as a watermark. In the present invention, image data such as a logo or a picture is used as a watermark to be inserted into a video signal, and a watermark included in the video signal can be extracted and visually confirmed.

Description

Method of inserting / extracting digital watermark and watermark inserting / extracting device using same {METHOD OF INSERTING / EXTRACTING DIGITAL WATERMARKS AND APPARATUS FOR USING THEREOF}

The present invention relates to a method for embedding a digital watermark in digital content or to extract a digital watermark embedded in digital content and an apparatus using the same. More specifically, the method of inserting / extracting a digital watermark to form an image of a logo or a picture or text of a certain content or to insert a watermark instead of a watermark in a random number form, and extract it in its original form so that it can be visually confirmed. And an insertion / extraction device using the same.

Recently, with the spread of computers and the Internet, interest in digital content copyright is increasing due to easy copying and distribution by digitalizing various contents. Digital watermarking, Digital Rights Management (DRM) technology, and Digital Object Identifier (DOI) provide various related technologies and solutions as digital copyright protection technology for protecting digital contents and paid services.

Digital watermarking technology is a technology widely used for verifying the copyright among the various related technologies described above and is a technique for inserting and protecting information related to copyright in the digital content.

Watermark refers to a mark that originated from the process of dissolving fiber in water in the process of making papyrus (paper) in ancient times, and then using a mold to squeeze out the water. In the Middle Ages, papermakers put marks on paper to prove that they were unique products. In today's papermaking process, when paper is wet, it is printed, dried, and printed on both sides. There is a picture that can only be checked through. It is also called a watermark.

Today, with the increase of digital media, the concept of digital watermark has emerged. As analog paper is replaced by the concept of digital paper, all analog media that used watermarks in the past have been digitized. As a hidden mark, the concept of digital watermark came into being. In summary, watermarking refers to any technical method of concealing and extracting a special form of watermark to protect a set of multimedia contents. Initially, the method of concealing the original multimedia asset itself was studied, but now, a powerful watermarking technique using many technical transformation methods is being developed.

There is a watermarking method using a key among the watermarking methods recently developed and widely used. This is to insert a series of key values into the video, generate a unique key or password owned by the user as a watermark, insert it into the picture or audio, detect it, and insert the key or password value into the picture or audio. It's a way of claiming that there is. In particular, the pseudo random sequence watermark among the key-based watermarking methods constitutes a watermark with a binary state of 0 and 1 or -1 and 1, and generally has a high autocorrelation series (for example, M -sequence, PN-sequence).

However, the watermarking method of the key method has a problem in that the extracted key value cannot be extracted and displayed. In other words, if you copy and use a picture or audio that someone has posted on the Internet, measure the correlation between the content (picture, audio, and video) and the key value. It can be claimed that it is in the audio, but it is vulnerable as evidence ability to show and claim its own ownership. In other words, whether or not the watermark exists can be confirmed, but it is difficult to insert and extract various copyright information.

In the conventional watermark insertion and detection apparatus as described above, a watermark generated by using a random number generated by a unique key or a user key is inserted into an image, and the watermark inserted in the image is correlated, etc. Since the detection result using only can only detect the fact that there is a watermark in the image, there is a problem in that the watermark cannot be determined visually and thus the reliability is low.

Accordingly, an object of the present invention is to provide a method of forming a watermark using an image such as text or a logo or a picture of a certain content in order to solve the above problems.

Another object of the present invention is to provide a method for embedding the watermark formed as described above and an insertion apparatus using the same.

Another object of the present invention is to provide a method for extracting a watermark visually in its original shape from video data inserted into a watermark as text or an image such as a logo or a picture, and an extraction apparatus using the same.

In order to achieve the above object, a method of embedding a digital watermark according to the present invention includes converting input data having a predetermined form to be displayed as a watermark into binary data, generating a random number according to a predetermined key value, and And adding the random number to the input image as a watermark according to the converted binary data.

In addition, the digital watermark embedding apparatus according to the present invention includes means for converting input data having a predetermined form to be displayed as a watermark into binary data, and a pseudonoise code for generating a random number which is a pseudonoise code according to a predetermined key value. And multiplication means for multiplying the random number and a predetermined constant according to the binary data, and adding means for adding the multiplied watermark and the input image.

In addition, the method of extracting a digital watermark according to the present invention comprises the steps of: a) generating a digital watermark using a random number which is a pseudo noise code according to a predetermined key value to extract a digital watermark embedded in an image signal; b) calculating a correlation between the digital watermark embedded in the video signal and the generated digital watermark, c) forming binary data having a predetermined value according to the correlation value, and d) And forming a bit stream of binary data formed by performing steps b) and c) on the entire video signal.

In addition, the apparatus for extracting a digital watermark according to the present invention is an apparatus for extracting a digital watermark embedded in an image signal, and generating a digital watermark using a random number which is a pseudo noise code according to a predetermined key value. Mark generation means, correlation degree calculation means for calculating a correlation between the digital watermark embedded in the video signal and the generated digital watermark, and binary data having a predetermined value according to the value of the correlation degree by the correlation means And watermark extracting means for generating a bit stream of binary data by performing the same on the entire video signal.

Hereinafter, a method of forming and inserting / extracting a digital watermark and an embedding / extraction apparatus using the same according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing the configuration of an embodiment of a digital watermark embedding apparatus according to the present invention;

2 illustrates an example of logo data that can be inserted in accordance with the present invention.

3 is a diagram illustrating a process of inputting logo data as a watermark on an input image using logo data of the form as shown in FIG. 2 according to the present invention;

4 is a view showing an example of the result of the logo data is inserted by the process in FIG.

5 is a block diagram schematically showing the configuration of another embodiment of a digital watermark embedding apparatus according to the present invention;

* Explanation of symbols for the main parts of the drawings

10 ... Input 20 ... Logo

130 ... adder 300 ... watermark generator

310 ... data converter 320 ... pseudo noise generator

330 ... Multiplier 340 ... Correlation Calculator

350 ... Watermark embedding determination unit

1 is a block diagram schematically showing the configuration of a digital watermark embedding apparatus according to the present invention.

The digital watermark inserting apparatus in FIG. 1 generates a pseudo noise code by a data converter 310, a unique key or a user key for converting a logo (picture or text document data) 20 into the form of binary data. Pseudo-noise code generator 320, the pseudo-noise code generated by the pseudo-noise code generator 320 and the pseudo-noise code by the user key and the converted data by the logo output from the data converter 310 A multiplier 330 for finally outputting a watermark to be inserted, and an adder 130 for adding the generated watermark to the input image 10.

3 illustrates an example of the operation of the watermark inserting apparatus having the above-described configuration, and a process of inputting the logo data as a watermark in the input image using the input logo data. Referring to Figure 4 showing an example of the result processed through the above process as follows.

First, the logo data (bitstream such as text) 20 to be inserted into the data converter 310 is input (step S100). The input data is converted into binary data (step S110). For example, it is assumed that when the logo data 20 as shown in FIG. 2 is converted into binary data, the logo data 20 is generated in the form of '01011 ... 01'. When a predetermined unique key or a user key input by the user is input (step S120), a pseudo noise code (random number) is generated using the seed as a seed (step S130).

At this time, the watermark is generated by distinguishing whether the binary data converted by the data converter 310 is '0' or '1' (step S140). That is, assuming that a watermark is generated when the binary data is '1' (reversely, two watermarks assigned to '0' and '1' can be used). The pseudo noise code generated by the generator 320 is multiplied by the multiplier 330. At this time, in order to adjust the intensity of the water mark by a factor of α, it may be multiplied by a pseudo noise code. Of course, if the intensity is not adjusted, it basically has a value of '1'. In addition, when the binary data is '0', the pseudo noise code is not added (step S150).

The above step shows a process for one bit of the bit stream constituting the binary-converted logo data, and the actual operation is performed sequentially for all the bits.

In this way, the digital watermark generated by performing the entire bit stream of the binary data constituting the logo data is added to the input image to complete the input image in which the watermark is inserted (step S150). The added result is as shown in FIG. That is, in the drawing, P means original data of the input image, P + PN means that the watermark is added to the input image, and P + 0 means that nothing is added to the input image.

5 is a block diagram schematically showing the configuration of another embodiment of a digital watermark embedding apparatus according to the present invention. The digital watermark embedding apparatus of FIG. 5 further includes a correlation calculator 340 and a watermark discriminator 350 as compared with the configuration of FIG. 1.

The above configuration is to determine whether the watermark is included in the input image before inserting the watermark, thereby preventing duplication of the watermark. That is, the correlation between the pseudonoise code generated by the unique key generated by the pseudonoise code generator 320 and the watermark included in the input image is calculated using the correlation calculator 340.

When the correlation is calculated, the watermark determination unit 350 determines whether the watermark is included in the input image 10 in consideration of the peak value and the position of the peak. If a watermark is included, the user is notified and work is terminated to prevent duplicate insertion. However, if not included, the watermark is inserted as described above.

As described above, the input signal having the watermark embedded therein is stored in the recording medium.

Next, a method for extracting a watermark from a video signal to which a watermark is inserted by the digital watermark embedding apparatus according to the present invention as shown in FIG. 1 will be described. The watermark extraction process is the reverse of the above insertion process.

Converts video signal data in various formats (MPEG, AVI, ASF, RM, etc.) with embedded watermark into raw video signal data decompressed by a format conversion device (row data: on the screen). Type displayed).

A watermark signal generated by inputting a user's key or a watermark signal generated by inputting a unique key through a watermark generating apparatus is generated by using a correlation calculator (not shown) of the video signal and the two signals. The correlation is calculated using Equation 1 below.

Here, Wimg refers to a watermarked image, that is, a signal that has undergone preprocessing, and Wm refers to a watermark formed by using a user key and a unique key. IFFT2 represents a two-dimensional inverse fast Fourier transform, FFT2 represents a two-dimensional fast Fourier transform, and conj represents a conjugate complex number.

Of course, this process may include a preprocessing process for enhancing the components of the watermark included in the video signal, and this preprocessing process serves to save the high frequency components of the video signal by using various types of filters. Can be processed. For example, a high boost filter, a Laplacian filter, and a DoG filter (Difference of Gaussian filter) are used.

If the value of the correlation between the watermark signal and the video signal generated by the user key or unique key calculated by Equation 1 is greater than the threshold value T, 1 is outputted. Binary data of a logo inserted by repeating the above process for an image obtained by dividing one image into blocks having a predetermined size (for example, '01011 ... 01' was inputted when a watermark was inserted into the image). Suppose you will extract '01011 ... 01'.

When the watermark data in the form of the extracted binary data is subjected to the reverse process of data conversion, the logo of the original inserted form can be formed.

As described above, the present invention converts data such as a logo into binary data, inserts it into an input image, and also extracts a watermark in the form of an inserted logo. Therefore, the reliability of the extracted watermark is high. In addition, a watermark redundancy check function at the time of inputting the watermark prevents duplication of watermarks and enhances copyright protection.

While the invention has been particularly shown and described with reference to the above embodiments, it has been used for the purpose of illustration and those of ordinary skill in the art, having the spirit and scope of the invention as defined in the appended claims. Various modifications can be made without departing.

Claims (20)

delete Converting input data having a predetermined form to be displayed as a watermark into binary data; Generating a random number that is a pseudo noise code according to a predetermined key value; And And if each value of the bit stream constituting the binary data corresponds to any one of two kinds of values constituting the binary data, adding the random number as a watermark to the input image. How to insert a digital watermark. 3. The method of claim 2, further comprising multiplying the random number by a predetermined constant value to adjust the strength of the watermark to be generated. 4. The method according to claim 2 or 3, wherein the input data is text. 4. The method of claim 2 or 3, wherein the input data is in the form of a picture. The method of claim 3, wherein after the random number generation step Calculating a correlation between the random number and the input image; And And determining whether the watermark included in the input image matches the watermark formed by the random number in consideration of the calculated correlation. How to insert a digital watermark. 4. The method according to claim 2 or 3, wherein the predetermined key is a user key set by a user who wants to embed a watermark. 4. The method according to claim 2 or 3, wherein the predetermined key is a unique key which is provided constantly regardless of the user. delete Means for converting input data having a predetermined form to be displayed as a watermark into binary data; Pseudonoise code generation means for generating a random number that is a pseudonoise code according to a predetermined key value; Multiplication means for multiplying the random number and the predetermined constant when respective values of the bit stream constituting the binary data correspond to any one of two kinds of values constituting the binary data; And And an adding means for adding the multiplied watermark and the input image. 11. The apparatus of claim 10, wherein said multiplication means is capable of changing said predetermined constant for adjusting the intensity of a watermark to be generated. 12. The apparatus of claim 10 or 11, wherein the input data is text. 12. The apparatus of claim 10 or 11, wherein the input data is in the form of a picture. A method of extracting a digital watermark embedded in a video signal, a) generating a digital watermark using a random number which is a pseudonoise code according to a predetermined key value; b) calculating a correlation between the digital watermark embedded in the video signal and the generated digital watermark; c) forming binary data having a predetermined value according to the correlation value; And and d) forming a bit stream of binary data formed by performing steps b) and c) on the entire video signal. 15. The method of claim 14, further comprising e) restoring an original shape included in a video signal to the bit stream of the binary data. 16. The method of claim 14 or 15, wherein the step c) assigns '1' to the binary data when the value of the correlation is greater than a threshold value and '0' to the binary data when the correlation value is smaller than a threshold value. Digital watermark extraction method characterized in that. 17. The method of claim 16, further comprising reinforcing a component of a digital watermark embedded in the video signal before performing step b). An apparatus for extracting a digital watermark embedded in a video signal, Digital watermark generating means for generating a digital watermark using a random number which is a pseudo noise code according to a predetermined key value; Correlation coefficient calculating means for calculating a degree of correlation between the digital watermark embedded in the video signal and the generated digital watermark; And watermark extracting means for generating binary data having a predetermined value according to the correlation value by the correlation means, and performing this on the entire video signal to form a bit stream of binary data. Watermark extraction device. 19. The apparatus of claim 18, wherein the watermark extracting means assigns '1' to the binary data when the value of the correlation is greater than a threshold value and '0' to the binary data when the correlation value is smaller than a threshold value. Digital watermark extraction apparatus. 20. The apparatus of claim 18 or 19, further comprising reconstruction means for reconstructing a bit stream of binary data extracted by said watermark extraction means to an original shape.