KR19990076464A - Apparatus and method for copying video data - Google Patents

Abstract

A reproduction control apparatus for video data and a method thereof are disclosed. The duplication control apparatus includes a modulation unit for spreading watermark information on a spectrum, generating a modulated watermark information by modulating the watermark information on the spectrum, and modulating the watermark information as an invisible signal, It is difficult to remove the watermark information by the user in addition to the author information including the insertion unit for generating the marked data, and the duplication control information for transferring the watermark information to the digital recorder is inserted into the moving image data, And is suitable for a real-time moving image compression / decompression apparatus by detecting without image data.

Description

Apparatus and method for copying video data

More particularly, the present invention relates to a duplication control apparatus and method for protecting copyrights used in an MPEG (Moving Picture Experts Group) moving picture compression / decompression apparatus.

Recently, as the spread of digital transmission and storage media including the Internet, digital satellite broadcasting, and DVD (Digital Versatile Disc) is rapidly increasing, copyright protection of digital multimedia data such as audio, video, have.

In particular, anyone can readily copy or edit a digital work using a personal computer (PC). In such a copy, commercial distribution can be made without deterioration of the quality and contents of the original data due to the inherent characteristics of the digital method It is creating new social problems surrounding copyright. Accordingly, digital watermark technology is attracting attention as a countermeasure against this.

In order to prevent illegal copying of digital A / V data, the following two methods are widely used. A method of using a digital watermark to embed an invisible signal into multimedia data for the purpose of preventing duplication of digital information and a copy control method using encryption and scramble.

The first method is a technology that originally prohibits the reproduction of digital A / V data because it informs descramble information and decryption information that can be operated only for normally purchased A / V works. Digital water such as an identifier (abbreviated as "ID"), a logo, or copy control information transmitted to a digital recorder in the A / V content data for the purpose of prohibiting unauthorized use of the information It is a technique that inserts mark information in the form of noise to make the user refrain from illegal copying.

However, the copy control method using encryption and scramble is capable of copying in units of bits and can be easily copied when the encrypted data is leaked. The copy control method for inserting a watermark into the conventional digital data includes A / V content data Since the ID, the logo, or the duplication control information transmitted to the digital recorder are inserted in the form of noise, the coding efficiency can be reduced. In order to detect the inserted watermark information, an original image is required as shown in FIG. 1 Real-time moving image compression / decompression apparatus.

1, the first frequency converter 11 converts a test image D "(i, j) into which a watermark is embedded into frequency-domain data, The second frequency converter 12 converts the original image D (i, j) into frequency domain data. The subtracter 13 subtracts the output of the first frequency converter 11 from the output of the second frequency converter 12 The watermark extractor 14 extracts a watermark from the subtraction result of the subtracter 13 and applies the extracted watermark signal X ^* (k). The comparator 15 compares the extracted watermark signal (X ^* ) and the original watermark signal X (k), and detects the extracted watermark signal as an actual watermark in accordance with the comparison result.

As described above, the watermark detection apparatus shown in FIG. 1 can be used in an apparatus that does not require real-time processing such as still image but requires a real-time processing. In a moving image compression / decompression apparatus using a high compression encoding scheme, There is a problem in that it is difficult to perform real-time processing.

In order to solve the above problems, an object of the present invention is to provide a duplication control apparatus capable of real-time processing and not requiring an original image.

It is another object of the present invention to provide a duplication control apparatus for use in a moving picture compression / decompression apparatus using block-based motion prediction / compensation.

It is another object of the present invention to provide a duplication control method capable of real-time processing and not requiring an original image.

In order to achieve the above and other objects, a duplication control apparatus according to the present invention is a duplication control apparatus using a watermark for copyright protection, comprising: spreading watermark information in a predetermined sub- A modulation unit for generating modulated watermark information by modulating using a noise row, and an insertion unit for inserting watermark information modulated with an invisible signal into the input image to generate watermarked data.

The duplication control apparatus of the present invention further includes a demodulation unit for demodulating the watermark information from the watermarked data using the pseudo noise sequence to generate demodulated watermark information, and a demodulation unit for demodulating the demodulated watermark information in a sub- And a detection unit for detecting the watermark information by summing.

According to another aspect of the present invention, there is provided a method of encoding and decoding video data by a block-based compression coding scheme, the method comprising: allocating a number of information bits and a pattern of watermark information; Generating spreading watermark information by diffusing the allocated watermark information into a chip rate composed of a predetermined number of blocks considering the degree of correlation, and generating moving image data in which the spread watermark information is inserted .

A duplication control method according to the present invention includes the steps of applying DCT coefficients to DCT transformed video data into which watermark information is embedded, generating IDCT data by performing IDCT transformation using only AC coefficients among DCT coefficients, Demodulating the IDCT data to generate demodulated data, and detecting watermark information by summing the demodulated data on a chip rate basis.

A duplication control method according to the present invention includes the steps of DCT transforming video data into which watermark information is embedded and performing block classification on the DCT region, extracting an insertion mask using the characteristics of the classified block, Applying IDCT coefficients to the DCT coefficients of the current DCT block and ACT coefficients excluding the AC coefficients of the classified block to apply the IDCT coefficients, applying the demodulated data by using the pseudo noise sequence from the IDCT coefficients, And detecting watermark information by summing the data on a chip rate basis.

1 is a block diagram of a conventional digital watermark detection apparatus.

2 is a block diagram of a general moving picture data encoding apparatus for facilitating understanding of the present invention.

3 is a diagram showing a structure of a video picture for MPEG-2 moving picture coding.

4 is a block diagram of an apparatus for encoding moving image data including a digital watermark according to an embodiment of the present invention.

5 is a block diagram of an apparatus for encoding moving image data including a digital watermark according to another embodiment of the present invention.

FIG. 6 is a detailed block diagram according to an embodiment of the watermark information inserter shown in FIGS. 4 and 5. FIG.

FIG. 7 is a detailed block diagram according to another embodiment of the watermark information inserter shown in FIGS. 4 and 5. FIG.

8A to 8D are diagrams for explaining a classification mask used in the block classifier shown in FIG.

FIG. 9 is a detailed block diagram according to an embodiment of the watermark information eliminator shown in FIG.

FIG. 10 is a detailed block diagram according to another embodiment of the watermark information eliminator shown in FIG.

11 is a block diagram of an apparatus for decoding general moving image data to help understand the present invention.

12 is a block diagram of an apparatus for decoding moving image data including a digital watermark according to an embodiment of the present invention.

13 is a block diagram of an apparatus for decoding moving image data including a digital watermark according to another embodiment of the present invention.

FIG. 14 is a detailed block diagram according to an embodiment of the watermark information detector shown in FIGS. 12 and 13. FIG.

Fig. 15 is a detailed block diagram according to another embodiment of the watermark information detector shown in Figs. 12 and 13. Fig.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of a video data copy control apparatus and method according to the present invention will be described with reference to the accompanying drawings.

2 is a block diagram of a general MPEG-2 moving picture data encoding apparatus for facilitating understanding of the present invention. The moving picture encoding apparatus performs intra-picture compression and inter-picture compression, In accordance with the sequence of compression of I, P, and B pictures.

A typical compression encoding of a video signal includes an intra (I) picture for reducing spatial redundancy information of picture information with information of only the current picture, as shown in FIG. 3 using a picture as a basic unit, (P) picture for compressing and coding the difference component between the previous I picture or the predicated picture (P picture) temporally preceding the current I picture or the P picture for reducing the correlation between the current I picture and the P picture, Directional pre-dicted (B) picture for compression-coding the difference component between the I or P pictures to be coded.

Meanwhile, the analog / digital (A / D) converter 102 shown in FIG. 2 converts the input original image signal into digital image data. Unlike MPEG-1, in MPEG-2, a frame DCT mode in which one frame is directly subjected to DCT and a field DCT mode in which one frame is regarded as two fields (odd field and excellent field) In addition, both have two DCT conversion modes. In most cases, field DCT transforms have higher compression efficiency for motion-rich images. The image data supplied from the A / D converter 102 is temporarily stored in the frame / field memory 104 in units of frames or fields to correspond to the DCT conversion mode.

The pixel data of the I picture is directly applied to the DCT (Discrete Cosine Transform) converter 108 without being affected by the subtracter 106. [ The DCT converter 108 converts the input image into 8-pixel × The quantizer 110 quantizes the DCT coefficients supplied from the DCT transformer 108 and the variable length coding and multiplexing unit 112 and the variable length coding and multiplexing unit 112 quantize the DCT coefficients supplied from the quantizer 110, And multiplexes the variable length coded data, the motion vector supplied from the motion predictor 124, and the additional information such as the quantization interval supplied from the rate controller 130 to generate a coded bit Output the stream. The buffer 114 temporarily stores the bit stream to adjust the bit rate of the encoded bit stream.

The compressed I picture supplied from the quantizer 110 is inversely quantized by an inverse quantizer 116 and an IDCT (Inverse Discrete Cosine Transform) converter 118 performs an IDCT transformation on the inversely quantized I picture to obtain a decompressed I And applies the picture to the adder 120. [ The decompressed I picture is transferred to the frame memory 122 which is intact as a buffer without being influenced by the adder 120 and is then stored in the frame memory 122 to predict and compress the P and B pictures.

Predictive coding of P and B pictures is also similar, and P picture compression will be described as an example. The image frames stored in the frame memory 122 are applied to the motion predictor 124. [ The motion predictor 124 calculates a motion vector using the current input image data and the previous or subsequent reference frame data stored in the frame memory 122 and outputs the motion vector to the VLC & MUX 112 and the motion compensator 126 do.

The motion compensator 126 reads a block corresponding to the motion vector predicted by the motion predictor 124 from the frame memory 122 and supplies it to the subtractor 106. [ The subtractor 106 subtracts the predicted block from the frame memory 122 through the motion compensator 126 from the block corresponding to the current picture to be decompressed, in pixel-by-pixel units. The difference or residue obtained by the subtraction of the subtractor 106 is applied to the DCT performer 108.

On the other hand, the compressed P picture is decoded in the inverse quantizer 116 and the IDCT converter 118, and the decoded data is applied to the first input of the adder 120. At the same time, each block of the reference frame stored in the frame memory 122 is accessed to predict the current picture, and the accessed block is applied to the second input of the adder 120 through the motion compensator 126. The adder 120 adds the encoded residual or difference and the data output from the motion compensator 126 to reconstruct an actual image. The reconstructed P picture from the adder 120 is then stored in the frame memory 122 for predictive encoding / decoding of the B picture.

On the other hand, the activity calculator 128 calculates the activity in the spatial domain of the input image stored in the frame / field memory 104 to set the initial buffer fullness, and calculates the quantization steps ). The rate controller 130 applies the actual quantization interval to the quantizer 110 and the VLC & MUX 112 based on the predicted quantization interval and the fullness of the buffer 114. At this time, the buffer 114 controls the quantization interval as feedback because the buffer fullness changes according to the amount of encoded bits. 2 may be referred to as a local decoder and may include a subtractor 106, an adder 120, a frame memory 122, a motion estimator 124, and a motion estimator 124. The inverse quantizer 116 and the IDCT transformer 118 shown in FIG. And motion compensator 126 may be referred to as motion prediction and compensator.

FIG. 4 is a block diagram of an apparatus for encoding moving image data in which a digital watermark is embedded according to an embodiment of the present invention. The apparatus includes a frame / field memory 204 and a frame / field memory 204 as compared with the moving picture data coding apparatus shown in FIG. A watermark information inserter 206 connected between the subtracter 208 and a watermark information eliminator 222 connected between the IDCT converter 220 and the adder 224 is further configured.

That is, the coding apparatus shown in Fig. 4 embeds watermark information only in an I picture used as a reference picture in MPEG-2 moving picture coding, and for P and B pictures for motion prediction and compensation based on an I picture, The watermark is removed from the locally decoded I picture used as a reference picture in motion prediction in order to reduce motion estimation and compensation errors due to the inserted watermark information.

5 is a block diagram of another embodiment of the apparatus for coding moving image data in which a digital watermark is embedded according to the present invention. In comparison with the apparatus for coding moving image data shown in FIG. 4, The only difference is that the eliminator is not configured.

5 inserts the watermark information only in the I picture used as the reference picture in the MPEG-2 moving picture coding by the watermark information inserter 205, and performs the motion prediction And the compensated P and B pictures, it has been found through experiments that there is no significant influence on the picture quality even if the watermark is not removed from the locally decoded I picture used as the reference picture in motion prediction. Therefore, The mark information remover was not configured.

FIG. 6 is a detailed block diagram according to an embodiment of the watermark information inserter 206 shown in FIG. 4 and the watermark information inserter 205 shown in FIG. 5, A transformer 238, accumulators and divider 240, a variance calculator 242, an amplifier 244, a duplication control information generator 246, a spectrum spreader 248, a pseudo random noise sequence (PN) Generator 250, a modulator 252, a second DCT converter 254, a multiplier 256, an adder 258, and an IDCT converter 260. [

The operation of the watermark information inserter shown in FIG. 6 will be described in connection with FIG. 4 for convenience of explanation, and the copy control information will be described as an example of watermark information.

6, the first DCT transformer 238 performs DCT transform on the I picture data x _i supplied from the frame / field memory 204 shown in FIG. 4 to generate DCT coefficients, The divider 240 accumulates the DCT coefficients for the N DCT blocks, calculates the accumulated DCT coefficients, and calculates the average variance per chip rate.

In order to detect a watermark inserted without an original image, the chip rate at which the watermark information is inserted needs to be reconstructed into an image having a relatively strong correlation with the image, Is defined as a block multiple of the DCT block to be hidden, i.e., N × 8 × 8. Here, the chip rate unit may be referred to as a sub-image unit.

The variance calculator 242 compares the current 8-pixel value supplied from the first DCT converter 238 × The amplifier 244 calculates the dispersion of the DCT block of 8 lines and if the dispersion (complexity) of the calculated DCT block is larger than the average dispersion of the chip rate supplied from the accumulators and the divider 240, factor) alpha . This amplification factor may be referred to as a visual sensitivity coefficient or embedding strength.

However, if the variance of the current DCT block is smaller than the average variance of the chip rate alpha = n, otherwise alpha = m. n is less than m. That is, if the complexity of the current DCT block is greater than the average complexity of the chip rate alpha .

Also, in the present invention, in order to prevent deterioration of image quality during MPEG coding by the duplication control information inserted in the form of noise and to impart robust characteristics to the elimination of inserted duplication control information, extended spectrum spreading ), And the copy control information (a _i ) generated by the copy control information generator 246 is as follows.

- one copy

- copy never (copy never)

- No more copy (no more copy)

- Other

In the embodiment of the present invention, there are four patterns of duplication control information, which can be represented by two bits.

Spectrum spreader 248 spectrally spreads and inserts duplicate control information bits within the chip rate. The pseudo noise row generator 250 generates a pseudo noise row p _i for modulation. The modulator 252 modulates the spread duplication control information b _i supplied from the spectrum spreader 248 using the pseudo noise sequence p _i supplied from the pseudo noise generator 250. The second DCT transformer 254 performs DCT transform on the modulated duplication control information supplied from the modulator 252.

The multiplier 256 multiplies the visual sensitivity coefficient < RTI ID = 0.0 > alpha And the DCT coefficient for the duplication control information supplied from the second DCT transformer 254 and applies the result of the multiplication to the adder 258. [ The adder 258 adds the DCT coefficient of the I picture of the source image supplied from the first DCT converter 238 and the multiplication result of the multiplier 256 and applies the addition result to the IDCT converter 260.

The IDCT converter 260 performs IDCT conversion on the addition result and outputs the picture x ' _{i in} which the duplication control information is inserted, that is, one of the four patterns of duplication control information is added to the original picture I picture in a noise form .

Here, an embodiment of a method of inserting copy control information is as follows.

First, the number of information bits of the inserted copy control information is allocated as shown in Equation (1), and the copy control information (a _{j, k} ) according to the number of allocated information bits and the pattern can be expressed by Equation (2).

Here, j = 1, ..., the number of information bits, and k = 1, 2, 3, 4 indicate one copy control information pattern among the four copy control information patterns.

Step 2: Duplicate the bits of the duplication control information in the chip rate. This can be expressed by Equation (3).

b _{i, k} = a _{j, k}

Here, j × chiprate ≤ i < (j + 1) × chiprate, and i is a pixel.

Step 3: Modulate the duplication control information using the pseudo noise sequence (p _i ) for modulation, which is a bipolar, as given in Equation (4).

Step 4: The moving picture data (x ' _i ) of the I picture into which the duplication control information is inserted is generated. This can be expressed by the following equation (5).

x _i '= IDCT (DCT (x _i ) +? (DCT (b _i , p _i )

here, alpha Is a visual sensitivity coefficient, DCT and IDCT units are 8 pixels × It is a block unit of 8 lines. Therefore, one of the four patterns of copy control information is inserted as watermark information into the original image I picture in the form of noise through the above equation (5).

FIG. 7 is a detailed block diagram according to another embodiment of the watermark information inserter 206 shown in FIG. 4 and the watermark inserter 205 shown in FIG. 5, Inserting the digital watermark of the spread spectrum technique using the pseudo noise sequence to prevent deterioration of the image quality in the MPEG coding by the inserted copyright information and the duplication control information and impart robust characteristics to the removed copyright information and duplication control information A block sorter 235, an insertion intensity calculator 237, an insertion mask generator 239, a watermark information generator 241, a spectrum spreader 243, a pseudo noise column generator 245 A modulator 247, a second DCT transformer 249, a multiplier 251, an adder 253 and an IDCT transformer 255.

The description of the operation of the watermark information inserter shown in FIG. 7 will be described in connection with FIG. 5 for convenience. The watermark information includes not only copy control information but also author information.

7, the first DCT transformer 233 transforms the intra-picture data I _mn (i, j) supplied from the frame / field memory 203 shown in Fig. × 8, and then the block classifier 235 performs block classification on the DCT block that has passed through the first DCT transformer 233 using the classification mask shown in FIG. 8 as follows. That is, each DCT block is classified according to the energy distribution using a classification mask.

- Flat block

- horizontal edge block

- vertical edge block

- diagonal edge block

- Detailed block

The classification mask used for the block classification in the present invention includes a vertical edge mask shown in FIG. 8 (a), a horizontal edge mask shown in FIG. 8 (b), a diagonal edge shown in FIG. 8 (c) Mask, and the complex block mask shown in Fig. 8 (d). Here, the mask may be referred to as a window. Additionally, 8 × 8, the AC coefficients among the DCT coefficients generated after the DCT transform on the block image are the vertical AC coefficients, as shown in FIG. 8 (a) Likewise 8 × 8 block image is a horizontal edge image, the AC coefficients among the DCT coefficients generated after the DCT transform on the block image are mainly AC coefficients in the vertical direction as shown in FIG. 8 (b). The classification of the DCT block performed in the block classifier 235 is expressed as follows.

That is, × When the value (B _sum ) obtained by subtracting the DC coefficient from the absolute value of the sum of DCT coefficients of 8 blocks is smaller than the first threshold value Th1, the class is classified as a flat block. The absolute sum of the result of multiplying each DCT coefficient of the DCT block by the horizontal edge mask shown in FIG. 8B is multiplied by _Hsum , and the _sum of the DCT coefficients of the DCT block and the DCT coefficients shown in FIG. the absolute sum of the results by multiplying the vertical edge mask multiplying V _sum La, and the DCT block absolute sum of the diagonal result by multiplying the edge mask multiplication shown in (c) of Figure 8 with each DCT coefficient d _sum La , If the value of the H _SUM , D _SUM , and V _SUM is greater than the second threshold value Th2, the class is classified as a block in the edge direction having the maximum value among them. B _sum is not smaller than the first threshold value Th1 and the values of H _sum , D _sum and V _sum are not larger than the second threshold value TH2, the class is classified as a complex block.

When the block classifier 235 classifies the block, the insertion strength calculator 237 calculates an insertion strength (hereinafter referred to as &quot; insertion strength &quot;) corresponding to the local property of each DCT block alpha ) Is calculated using Equation (7).

Insertion strength ( alpha ) Is adaptively selected according to the total energy of each block. If the block has a relatively small energy, the insertion strength ( alpha ) And a block having a relatively large energy, the insertion strength ( alpha ).

The insertion mask generator 239 generates an insertion mask _tmn (i, j) indicating the position at which the watermark information is inserted according to the characteristics of the block classified by the block classifier 235 using Equation (8).

That is, if the characteristic of the current DCT block is classified as a flat block in the block classifier 235 and the coefficients of the DCT block have a value larger than the B _sum value multiplied by the third threshold value Th3, i, j) is set to " 0 &quot;, i.e., if the block is a flat block, the watermark information is not inserted. Otherwise, the value of the insertion mask (t (0,0)) of the DC coefficient position is set to "0" and the value of the insertion mask (t (i, j) If the insertion mask having the subtracted value occurs, that is, the block excluding the flat block, the watermark information is inserted at a position excluding the DC position and the position where the classification mask of the block is " 1 &quot;. The main reason for the watermark extraction error is that the watermark information is inserted into a relatively large DCT coefficient. In the present invention, the insertion mask is used to prevent the watermark information from being inserted into a relatively large DCT coefficient. The insertion mask is opposite to the block classification mask.

On the other hand, the watermark information generator 241 generates watermark information w _m . Here, author information and duplication control information inserted in the digital watermark technique of the present invention can be configured as follows.

- Author information is: N bits,

- Replication control information: 2 bits

Therefore, the watermark information amount to be inserted is M = N + 2 bits. Among these, the copy control information is composed of the following four patterns.

- one copy

- copy never (copy never)

- No more copy (no more copy)

- Other

Spectrum spreader 243 spectrally spreads and inserts the watermark information bits within the chip rate. The pseudo noise row generator 245 generates a pseudo noise row p _mn (i, j) for modulation. The modulator 247 modulates the diffused watermark information w _m supplied from the spectrum spreader 243 using the pseudo noise sequence p _mn (i, j) supplied from the pseudo noise heat generator 245 . That is, the thus-spread author information and duplication control information are modulated into a pseudo noise sequence known only to the author, and then DCT transformed by the second DCT transformer 249.

The multiplier 251 multiplies the insertion strength calculated from the insertion strength calculator 237 alpha ), Multiplies the insertion mask value _tmn (i, j) supplied from the insertion mask generator 239 by the DCT coefficient for the watermark information supplied from the second DCT converter 249, and outputs the multiplication result to the adder 253 .

The adder 253 adds the DCT coefficient of the I picture of the source image supplied from the first DCT converter 233 through the block classifier 235 to the multiplication result of the multiplier 256 and outputs the result of addition to the IDCT converter 255 . Here, the addition result of the adder 253 is expressed as follows.

The IDCT converter 255 performs IDCT conversion on the addition result of the adder 253 and transmits the picture I ' _mn (i, j) into which the watermark information is inserted to the MPEG encoder.

That is, in the watermark embedding process of the present invention, the watermark is intensively inserted into a relatively small DCT coefficient so that image quality degradation due to watermark embedding and watermark embedding using only watermarked MPEG- It is intended to reduce detection error in detection.

Here, the method of inserting watermark information can be performed as follows.

Step 1: DCT-transform the inputted intra picture data and perform block classification on the DCT area using Equation (6).

A second step; After the block classification is performed, the insertion strength corresponding to the local property of each DCT block is obtained using Equation (7) above, and the insertion mask indicating the insertion position corresponding to the characteristic of the classified block is calculated using Equation (8) Occurs.

Third step: The watermark information to be inserted is configured to spread the watermark information within the chip rate represented by the following equation (10).

Here, horizontal_pixel_size is the number of pixels per line, vertical_line_size is the number of lines per frame, block_size is 8 (pixels) × 8 (lines), and M is the number of copyright information and control information bits to be inserted.

Step 4; Diffused watermark information is modulated using a pseudo noise sequence and DCT transformed.

Step 5: The watermarked image is generated by inserting the modulated watermark information matching the characteristic of the block from the insertion strength and the insertion mask value in the DCT region.

On the other hand, when digital watermark information in the form of a noise is inserted into an I picture of the original image to be coded, and the coded I picture is locally decoded to be used as a reference in predicting motion of P and B pictures, An error may occur in predicting the motion of the P and B pictures.

In order to solve this problem, as shown in FIG. 9, digital watermark information embedded in an I picture is removed at the time of local decoding, thereby reducing motion estimation and compensation errors in the time domain for P and B pictures .

FIG. 9 is a detailed block diagram according to one embodiment of the watermark information remover 222 shown in FIG. 4, which includes a first DCT transformer 262, an accumulator and divider 264, A calculator 266, an amplifier 268, a spectrum spreader 270, a modulator 272, a second DCT converter 274, a multiplier 276, a subtractor 278 and an IDCT converter 280.

Compared with the configuration of the watermark information eliminator shown in Fig. 9 and the configuration of the watermark information inserter shown in Fig. 6, the watermark information eliminator in place of the adder 258 of the watermark information inserter is a watermarked I it is different to that by subtracting the DCT coefficients for the copying control information from the DCT coefficients for the picture (x _'i) a subtracter for extracting a DCT coefficient to the original I-picture (x _i) (278) configuration. The duplication control information generator for generating the duplication control information a _i to be applied to the spectrum spreader 270 is not separately configured for simplification of the circuit but is shared with the duplication control information generator 246 shown in Fig. The pseudo noise generator for generating the pseudo noise sequence p _i applied to the modulator 272 is also shared with the pseudo noise generator 250 shown in Fig.

Although the configuration of the watermark information eliminator shown in FIG. 9 can be shared with the blocks identical to those of the duplication control information inserter shown in FIG. 6, the watermark information eliminator may be separately configured as shown in FIG. 9 desirable. Because the watermarked I picture x ' _i input to the first DCT transformer 262 shown in FIG. 9 is supplied to the DCT transformer 210, the quantizer 212, the inverse quantizer 218 Since the data loss is inevitable through the IDCT converter 220, it is not the same as the watermarked I picture output from the watermark information inserter 206 shown in FIG.

FIG. 10 is a detailed block diagram according to another embodiment of the watermark information eliminator 222 shown in FIG. 4, which includes a first DCT transformer 257, a block sorter 259, an insertion intensity adjuster 261, an insertion mask generator 263, a spectrum spreader 265, a modulator 267, a second DCT converter 269, a multiplier 271, a subtractor 273 and an IDCT converter 275.

10 and the configuration of the watermark information inserter shown in FIG. 7, the watermark information inserter 205 can be replaced by the watermark information inserter 205, instead of the adder 253, It is by subtracting the DCT coefficient of the watermark information in the DCT coefficient to the watermark I picture _{(I 'mn (i, j} )) extracts the DCT coefficients for the original I-picture _{(I mn (i, j)} ) The subtracter 273 is constituted. The watermark generator for generating the watermark information w _m applied to the spectrum spreader 265 for simplification of the circuit is not separately configured but is shared with the watermark information generator 241 shown in Fig. Noise column generator that generates a pseudo noise sequence p _mn (i, j) applied to the pseudo noise generator 265 shown in FIG.

FIG. 11 is a block diagram of a general MPEG-2 moving image data decoding apparatus for facilitating understanding of the present invention, wherein decoding is performed in the reverse order of the encoding order. In Fig. 11, the buffer 302 temporarily stores the MPEG-2 encoded bit stream. The variable length decoding and demultiplexing unit (VLD & DEMUX) 304 detects a quantization interval and a motion vector from the variable length decoded data by variable length decoding the coded bit stream, and the quantization interval and the variable length decoded data are decoded by an inverse quantizer 306, and the motion vector is applied to the motion compensator 312.

The inverse quantizer 306 inversely quantizes the variable length decoded data supplied from the VLD & DEMUX 304 according to the quantization interval, and the IDCT converter 308 converts the inverse quantized data supplied from the inverse quantizer 306 IDCT conversion.

The adder 310 outputs the decoded picture supplied from the IDCT transformer 308 through the buffer 314 as it is if it is an I picture and outputs it to the motion compensator 312 in order to decode the P or B picture with reference to the I picture. And adds the motion compensated signal and the currently decoded P or B picture using the motion vector output from the motion compensator 312 and outputs the result through the buffer 314 if the P or B picture is the P or B picture.

That is, the P picture can be completely reconstructed through motion compensation using the decoded previous I picture or P picture, and the B picture can be reconstructed in the future as well as the previous I or P picture, The motion compensator 312 stores the previous I and P pictures and the subsequent I and P pictures, since the motion compensator 312 can decode the I and P pictures using the motion vector.

FIG. 12 is a block diagram of an apparatus for decoding moving image data in which a digital watermark is embedded according to the present invention. A watermark information detector (not shown) for detecting watermark information embedded with moving image data on an encoded bit stream And a watermark information remover 412 for removing a watermark from a decoded I picture used as a reference picture in motion compensation to prevent an error in motion compensation of the P and B pictures by the watermark information Which is different from the general MPEG-2 moving picture data decoding apparatus shown in FIG.

That is, the watermark information detector 410 detects the watermark information from the decoded I picture supplied from the IDCT converter 408, and applies it to the digital recorder to control illegal copying. The watermark information remover 412 removes the watermark information from the decoded I picture used as the reference picture output from the IDCT converter 408 to prevent an error in motion compensation of the P and B pictures by the watermark information And applies it to the adder 414. Here, the watermark information remover 412 may be configured similar to the configuration shown in Figs.

Namely, if the watermark information eliminator 412 shown in Fig. 12 has the configuration of the watermark information eliminator shown in Fig. 9, the watermarked I picture input to the first DCT transformer 262 corresponds to the IDCT Watermarked I picture outputted from the converter 408 and the duplication control information a _i input to the spectrum spreader 270 is different from the duplication control information detected by the watermark information detector 410, 10, the watermarked I picture input to the first DCT transformer 257 becomes the watermarked I picture output from the IDCT transformer 408 shown in FIG. 12 And the watermark information w _m input to the spectrum spreader 265 is watermark information detected by the watermark information detector 410.

Therefore, when the coding apparatus excludes the influence of the watermark in coding the P or B picture, the decoding apparatus also removes the watermark detected in the decoding of the I picture, Errors can be reduced.

13 is a block diagram according to another embodiment of the apparatus for decoding moving image data in which a digital watermark is embedded according to the present invention. The difference from the conventional MPEG-2 moving picture data decoding apparatus shown in FIG. 11 is that the buffer 413 And further comprises a watermark information detector 415 for detecting watermark information from the decoded video data.

14 is a detailed block diagram according to an embodiment of the watermark information detector 412 shown in Fig. 12 and the watermark information detector 415 shown in Fig. 13, and the watermark information detector includes a DCT converter 420, A DC coefficient remover 422, an IDCT converter 424, a pseudo noise heat generator 426, a demodulator 428, a circuit 430, a duplication control information pattern generator 432 and a comparator 434.

The operation of the watermark information detector shown in Fig. 14 will be described with reference to Fig. 12 for convenience of explanation, and it is assumed as duplication control information as an example of watermark information. 14, the DCT transformer 420 DCT transforms the watermarked I picture data x ' _i supplied from the IDCT transformer 408 shown in FIG. 12, and the DC coefficient eliminator 422 transforms DCT transformed DCT coefficients The DC coefficient among the DCT coefficients supplied from the IDCT converter 420 is removed, and the IDCT converter 424 performs IDCT conversion on the AC coefficient. This is because the watermark information is detected in the AC coefficient among the DCT coefficients because the watermark information is inserted as a noise form.

The demodulator 428 demodulates the IDCT data using the pseudo noise sequence p _i generated from the pseudo noise sequence generator 426 and adds the data b _i demodulated in units of chip rate to the multiplexer 430, Control information is detected. That is, if the result of the addition is positive, the copy control information is " 1 &quot;, and if it is negative, the copy control information is " -1 &quot;. The pseudo noise generator 426 may be shared with a pseudo noise generator used in the encoder.

The comparator 434 compares the output of the convolution circuit 430 with the replica control information pattern generated by the replica control information pattern generator 432. If the comparison result is smaller than the threshold value TH, And otherwise outputs copy control information indicating no copy control information.

An example of the detected copy control information is as follows.

- one copy

- copy never (copy never)

- No more copy (no more copy)

- Other

- no watermark

In the present invention, in order to detect a watermark inserted without an original image, since the chip rate of the duplication control information in the coding apparatus reconstructs the image in an area where the correlation of the image is relatively strong, × 8 × 8 in the unit of the chip rate.

One embodiment of a method of detecting duplication control information is as follows.

Step 1: The decoded I picture is subjected to DCT conversion on a DCT block basis.

Step 2: IDCT data is generated by IDCT using only AC coefficient among DCT coefficients

Step 3: Demodulate IDCT data using the same pseudo noise sequence p _i used in the encoding apparatus to generate demodulated data b _i .

Step 4: sums the demodulated data (b _i) at a chip rate increments. This can be expressed by Equation (11).

Step 5: Restore the inserted duplication control information using the result of the fourth step, and express it as Equation (12).

Step 6: If the watermark information is the copy control information, the inserted copy control information is compared with the copied copy control information bit and the copy control information pattern, or information indicating that there is no watermark information is generated. This expression is given by Equation (13), and the detected copy control information is transferred to the digital recorder to control illegal copying.

Here, pattern_a _{j, k} is a duplication control information pattern, and if simiarity_test is larger than the threshold, it means no watermark.

FIG. 15 is a detailed block diagram according to another embodiment of the watermark information detector 412 shown in FIG. 12 and the watermark information detector 415 shown in FIG. 13, and the watermark information detector includes a DCT converter 417, A block sorter 419, an insertion mask extractor 421, a multiplier 423, a subtractor 425, an IDCT converter 427, a demodulator 429 and a pseudo noise column generator 431 and a conferencing channel 433 .

The operation of the watermark information detector shown in Fig. 15 will be described in conjunction with Fig. 13 for convenience of explanation, and the detected watermark information includes both author information and duplication control information. In Fig. 15, the DCT transformer 417 performs DCT transform on the decoded video data supplied from the buffer 413 shown in Fig. Let the data input to the DCT transformer 417 be R _mn (i, j).

The block classifier 419 may be constructed in the same manner as the block classifier 235 shown in FIG. 7, and the DCT block supplied from the DCT transformer 417 may be a flat block, an edge block, Cognition.

The insertion mask extractor 421 extracts the insertion mask t _mn (i, j) from the block classified by the block classifier 419 through the above expression (8). The multiplier 423 multiplies the coefficients of the DCT block output through the block classifier 419 by the insertion mask value t _mn (i, j) extracted by the insertion mask extractor 421, Can be expressed by Equation (14).

_{F (E mn (i, j} )) = F ((R mn (i, j)) ⋅t mn (i, j)

The subtracter 425 subtracts the multiplication result of the multiplier 423 from each coefficient of the DCT block output through the block sorter 419, thereby removing the DC coefficient of the DCT block and the AC coefficient of the classified block. And the IDCT converter 427 performs IDCT conversion on the result of the subtractor 425 to an integer precision.

The demodulator 429 is IDCT converter 427 output (E _mn (i, j)) demodulated by the pseudo noise column (p _mn) generated in the pseudo-noise heat generator 431, and from the demodulation result (b in _mn can be expressed as shown in Equation (15). The pseudo noise generator 426 may be shared with a pseudo noise generator used in the encoder.

The conferencing circuit 433 selects only one of the pieces of information of {-1, 1} output from the demodulator 429 on a block-by-block basis and adds the result to the chip rate unit to obtain a signum function . That is, if the sign of the result of the conferencing channel 433 is positive, the detected watermark information is " 1 ", and if it is negative, the detected watermark information is " -1 ". This can be expressed by Equation (16).

Further, the conferencing circuit 433 selects only one of the last {-1,1} pieces of information on a chip rate basis using the above expression (16), and detects inserted author information and duplication control information. Since zero can occur other than {-1,1} in the summation process according to Equation (16), it is compensated by using Equation (17). Namely, the sign of the block having the largest value among the values obtained by adding the information of {-1,1} in each block within the chip rate unit and taking the absolute value is taken to detect the watermark information.

The watermark information detector shown in Fig. 15 can further be configured with a duplication control information pattern generator and a comparator as shown in Fig. 14 when the watermark information is duplication control information.

Here, another embodiment of the method of detecting watermark information is as follows.

Step 1: DCT-transform the input intra-picture data and perform block classification on the DCT region using Equation (6).

A second step; The insertion mask is extracted using the characteristics of the classified block.

A third step; The DC coefficient of the current DCT block and the AC coefficient of the classified block are removed using the extracted insertion mask to perform IDCT conversion with an integer precision.

Step 4; And demodulates the result of the IDCT conversion using the pseudo noise sequence.

Step 5: Detect watermark information by summing the demodulated data on a chip rate basis.

The present invention can be applied not only to the MPEG-2 moving picture compression / decompression apparatus but also to the block-based moving picture codec. In addition, both the compressed data and the uncompressed data can be inserted and detected using the present invention, and watermark information can be inserted and detected in still picture data as well as moving picture data using the present invention .

INDUSTRIAL APPLICABILITY As described above, the present invention minimizes deterioration of image quality of a moving picture compression / decompression apparatus employing an MPEG moving picture coding algorithm, and can prevent illegal copying using a digital recorder or the like.

In addition, the present invention inserts watermark information such as author information, as well as duplication control information transmitted to a digital recorder, which is difficult to remove by watermark information by a user, into video data, and detects inserted watermark information even without an original image And can be applied to a real-time moving image compression / decompression apparatus.

Claims (36)

A copy control apparatus using a watermark for copyright protection, comprising: A modulation unit for spreading watermark information on a spectral basis in a sub-image unit of a predetermined size, and modulating the watermark information using a pseudo noise sequence to generate modulated watermark information; And And an insertion unit for inserting the modulated watermark information into an input image with an invisible signal to generate watermarked data. The duplication control apparatus according to claim 1, further comprising an insertion strength adjusting unit for controlling an insertion strength of the modulated watermark information. The apparatus of claim 1, wherein the input image is a block input image, and the sub-image unit is a unit of a chip rate consisting of a predetermined number of blocks of a predetermined size taking into account the degree of correlation. [4] The apparatus of claim 3, wherein the insertion strength adjusting unit uses the variance of the blocked input image and the average variance of the chip rate unit, if the variance of the blocked input image is larger than the average variance of the chip rate, And adjusts the intensity of the mark information. 4. The method of claim 3, wherein the insertion strength adjusting unit is configured such that a block having a relatively small energy according to the total energy of each block of the blocked input image has a small insertion strength and a block having a relatively large energy has a large insertion strength Wherein the control unit controls the reproduction control unit. The method according to claim 1, A demodulation unit for demodulating watermark information from the watermarked data using the pseudo noise sequence to generate demodulated watermark information; And And a detection unit for detecting the watermark information by summing the demodulated watermark information in units of sub-images. The image processing apparatus according to claim 6, further comprising: a comparison unit for comparing the detected watermark information with a reference pattern and outputting the detected watermark information as actual watermark information according to the comparison result or generating information indicating that there is no watermark information Further comprising a copy control device. A variable length encoder for performing variable length coding on the quantized data; a variable length encoder for quantizing the DCT coefficients by applying a discrete cosine transform (DCT) to the input image; a variable length encoder for quantizing the quantized data; 1. A moving picture data encoding apparatus comprising a local decoder for local decoding data, and a motion prediction and compensator for predicting and compensating for motion from the locally decoded data, And a watermark information inserter for inserting watermark information into intra (I) picture data of the input image and applying the watermark information to the DCT performer. 9. The method of claim 8, Further comprising a watermark information remover for removing the watermark information from the locally decoded I picture data and for applying the I picture data from which the watermark information is removed to the motion prediction and compensator. The watermark embedding apparatus according to claim 9, A first DCT transformer for DCT transforming the I picture data; A first calculator for accumulating the outputs of the first DCT transformer and calculating an average variance in units of a chip rate in units of a predetermined number of DCT blocks considering the degree of correlation; A second calculator for calculating a variance of a current DCT block supplied from the first DCT transformer; A first amplifier for adjusting the visual sensitivity coefficient if the variance of the current DCT block is greater than an average variance of the chip rate; A first spread spectrum spreader for spreading watermark information within the chip rate; A first modulator for modulating the watermark information output from the first spread spectrum unit using a pseudo noise sequence to generate modulated watermark information; And And inserting means for inserting the modulated watermark information in consideration of the visual sensitivity coefficient into the I picture on the DCT region. 11. The apparatus according to claim 10, A second DCT transformer for DCT transforming the modulated watermark information; A first multiplier for multiplying a DCT coefficient for watermark information supplied from the second DCT transformer by the visual sensitivity coefficient; An adder for inserting a DCT coefficient of watermark information obtained by multiplying a DCT coefficient for an I picture supplied from the first DCT transformer by a visual sensitivity coefficient outputted from the multiplier; And And a first IDCT converter for performing inverse discrete cosine transform (IDCT) on the output of the adder. 12. The information processing apparatus according to claim 11, A third DCT transformer for DCT transforming the locally decoded I picture data; A third calculator for accumulating outputs of the third DCT transformer to calculate an average variance of the chip rate units; A fourth calculator for calculating a variance of a current DCT block supplied from the third DCT transformer; A second amplifier for amplifying a visual sensitivity coefficient if a variance of a current DCT block supplied from the fourth calculator is greater than an average variance of a corresponding chip rate supplied from the third calculator; A second spread spectrum spreader for spreading the watermark information within a chip rate; A second modulator for modulating the watermark information output from the second spread spectrum by using the pseudo noise sequence; And And extracting means for extracting the modulated watermark information considering the visual sensitivity coefficient from the locally decoded I picture on the DCT region. 13. The apparatus according to claim 12, A fourth DCT transformer for DCT transforming the modulated watermark information supplied from the second modulator; A second multiplier for multiplying a DCT coefficient for watermark information supplied from the fourth DCT transformer by a visual sensitivity coefficient supplied from the second amplifier; A subtracter for subtracting the DCT coefficient of the watermark information multiplied by the visual sensitivity coefficient supplied from the multiplier from the DCT coefficient for the locally decoded I picture data supplied from the third DCT transformer; And And a second IDCT converter for IDCT-converting the output of the subtracter. The watermark embedding apparatus according to claim 9, A first DCT transformer for DCT transforming the I picture data in units of DCT blocks; A first block classifier for classifying each DCT block supplied from the first DCT transformer as an edge block, a complex block, and a flat block according to an energy distribution thereof using a classification mask; A first insertion strength calculator for adaptively calculating an insertion strength according to the total energy of the classified block; A first insertion mask generator for generating an insertion mask indicating an insertion position of watermark information according to the classified block; A first spread spectrum spreader for spreading watermark information within a chip rate composed of a predetermined number of DCT blocks considering a degree of correlation; A first modulator for modulating the watermark information output from the first spread spectrum unit using a pseudo noise sequence to generate modulated watermark information; And And inserting means for inserting the modulated watermark information into the I picture on the DCT area according to the insertion strength and the insertion mask. 15. The apparatus of claim 14, wherein the inserting means A second DCT transformer for DCT transforming the modulated watermark information; A first multiplier for multiplying a DCT coefficient for watermark information supplied from the second DCT transformer, the insertion strength and an insertion mask; An adder for inserting a DCT coefficient of watermark information multiplied by an insertion mask and an insertion strength output from the multiplier into a DCT coefficient for an I picture supplied from the first DCT transformer; And And a first IDCT converter for performing inverse discrete cosine transform (IDCT) on the output of the adder. 15. The watermark detection apparatus according to claim 14, A third DCT transformer for DCT transforming the locally decoded I picture data; A second block classifier for classifying each DCT block supplied from the third DCT transformer as an edge block, a complex block, and a flat block according to an energy distribution thereof using a classification mask; A second insertion strength calculator for adaptively calculating the insertion strength according to the total energy of the classified block; A second insertion mask generator for generating an insertion mask indicating the insertion position of the watermark information according to the classified block; A second spread spectrum spreader for spreading the watermark information within the chip rate; A second modulator for modulating the watermark information output from the second spread spectrum unit using the pseudo noise sequence to generate modulated watermark information; And And extraction means for extracting the modulated watermark information considering the insertion strength and position from the locally decoded I picture on the DCT region. The image processing apparatus according to claim 16, A fourth DCT transformer for DCT transforming the modulated watermark information; A second multiplier for multiplying a DCT coefficient for the watermark information supplied from the fourth DCT transformer, the insertion strength and an insertion mask; A subtractor for subtracting a DCT coefficient of watermark information multiplied by an insertion mask from an insertion strength supplied from the second multiplier, from a DCT coefficient for an I picture supplied from the third DCT transformer; And And a second IDCT converter for IDCT-converting the output of the subtracter. The duplication control apparatus according to claim 16, wherein the first and second insertion strength calculators increase the insertion strength of a block having a relatively small energy and the insertion strength of a block having a relatively large energy. A variable length decoder for variable length decoding the received coded bit stream to apply variable length decoded data and a motion vector, an inverse quantizer for applying inverse quantized data by inverse quantizing the variable length decoded data, There is provided an apparatus for decoding moving picture data comprising an IDCT transformer for performing inverse discrete cosine transform (IDCT) of quantized data and applying decoded data, and a motion compensator for performing motion compensation using the motion vector from the decoded data, And a watermark information detector for detecting watermark information from the decoded intra (I) picture data. 20. The apparatus of claim 19, And removing the watermark information embedded in the decoded I picture data and applying the removed watermark information to the motion compensator. The apparatus of claim 20, wherein the watermark information detector comprises: A first DCT transformer for DCT transforming the decoded I picture data; A first IDCT transformer for IDCT transforming DCT coefficients excluding DC coefficients; A demodulator for demodulating an output of the first IDCT transducer using a pseudo noise sequence; And And a conferencing unit for combining the demodulated data with a unit of chip rate consisting of a predetermined number of DCT blocks considering the degree of correlation and restoring the watermark information. 22. The apparatus of claim 21, wherein the watermark information detector comprises: Further comprising a comparator for comparing the restored watermark information with a predetermined duplication control information pattern to detect duplication control information according to a result of the comparison or generating information indicating that there is no watermark information. 23. The information processing apparatus according to claim 22, A second DCT transformer for DCT transforming the decoded I picture data; A first calculator for accumulating outputs of the second DCT transformer and calculating an average variance of the chip rate units; A second calculator for calculating a variance of a current DCT block supplied from the second DCT transformer; An amplifier for amplifying the visual sensitivity coefficient if the variance of the current DCT block is greater than an average variance of the chip rate; A spectrum spreader for spreading the watermark information within a chip rate; A modulator for modulating the watermark information output from the spectrum spreader using a pseudo noise sequence; A third DCT transformer for DCT transforming the modulated watermark information supplied from the modulator; A multiplier for multiplying a DCT coefficient of the watermark information supplied from the third DCT transformer by the visual sensitivity coefficient; A subtractor for subtracting the DCT coefficient of the watermark information multiplied by the visual sensitivity coefficient outputted from the multiplier from the DCT coefficient for the decoded I-picture data supplied from the second DCT transformer; And And a second IDCT converter for IDCT-transforming the output of the subtracter to apply I picture data whose watermark information is removed to the motion compensator. The apparatus of claim 20, wherein the watermark information detector comprises: A first DCT transformer for DCT transforming the decoded I picture data in units of DCT blocks; A first block classifier for classifying each DCT block supplied from the first DCT transformer as an edge block, a complex block, and a flat block according to an energy distribution thereof using a classification mask; An insertion mask extractor for extracting a value of an insertion mask indicating an insertion position of watermark information according to the classified block; A first multiplier for multiplying the coefficients of the DCT block output through the block classifier by the insertion mask value; A first subtractor for subtracting the multiplication result of the multiplier from each coefficient of the DCT block outputted through the block classifier to remove the DC coefficient of the DCT block and the AC coefficient of the classified block; A first IDCT converter for IDCT-converting the result of the first subtracter; A demodulator for demodulating an output of the first IDCT transducer using a pseudo noise sequence; And And a conferencing unit for combining the demodulated data with a unit of chip rate consisting of a predetermined number of DCT blocks considering the degree of correlation and restoring the watermark information. The apparatus of claim 24, wherein the watermark information detector comprises: Further comprising a comparator for comparing the restored watermark information with a predetermined duplication control information pattern to detect duplication control information according to a result of the comparison or generating information indicating that there is no watermark information. The apparatus of claim 24, wherein the watermark information remover comprises: A second DCT transformer for DCT transforming the decoded I picture data; A second block classifier for classifying each DCT block supplied from the second DCT transformer as an edge block, a complex block, and a flat block according to an energy distribution thereof using a classification mask; An insertion strength calculator for calculating the insertion strength adaptively according to the total energy of the classified block; An insertion mask generator for generating an insertion mask indicating an insertion position of the watermark information according to the classified block; A spectrum spreader for spreading watermark information within the chip rate; A modulator for modulating the watermark information output from the spectrum spreader using the pseudo noise sequence; A third DCT transformer for DCT transforming the modulated watermark information; A second multiplier for multiplying a DCT coefficient for watermark information supplied from the third DCT transformer, the insertion strength and an insertion mask; A second subtractor for subtracting an output of the second multiplier from a DCT coefficient for an I picture supplied from the second DCT transformer; And And a second IDCT converter for IDCT-converting the output of the second subtractor. A method of encoding and decoding video data by a block-based compression encoding scheme, the method comprising: (a) configuring watermark information by allocating a bit number and a pattern of watermark information; (b) diffusing the watermark information into a chip rate composed of a predetermined number of blocks considering a degree of correlation to generate watermark information spread; And (c) inserting the diffused watermark information into the video data. 28. The method of claim 27, wherein the video data is intra picture data. 28. The method of claim 27, (d) modulating the spread watermark information using a pseudo noise sequence to generate modulated watermark information; And (e) controlling the insertion strength of the modulated watermark information. The method as claimed in claim 29, wherein, in the step (e), if the variance of the currently input image is greater than the mean variance of the chip rate using the variance of the input image block and the average variance of the chip rate, And the intensity of the information is adjusted. The method of claim 29, wherein, in the step (e), a block having a relatively small energy according to the total energy of each block of the blocked input image has a small insertion strength and a block having a relatively large energy has a large insertion strength Wherein the copy control method comprises the steps of: 29. The method of claim 28, (f) performing DCT on the intra-picture data in which the watermark information is inserted and applying a DCT coefficient; (g) performing IDCT transformation on only the AC coefficients among the DCT coefficients to generate IDCT data; (h) demodulating the IDCT data using a pseudo noise sequence to generate demodulated data; And (i) detecting watermark information by summing the demodulated data for each chip rate. 33. The method of claim 32, (j) comparing the detected watermark information with a predetermined duplication control information pattern to detect duplication control information or generating information indicating that there is no watermark (j). 29. The method of claim 28, (f1) DCT transforming the intra picture data into which the watermark information is inserted, and classifying the blocks on the DCT area; (g1) extracting an insertion mask using characteristics of the classified block; (h1) applying an IDCT coefficient on the DCT coefficients of the current DCT block and the DCT coefficients excluding the AC coefficients of the classified block using the extracted insertion mask to perform IDCT transformation; (i1) demodulating the IDCT coefficients using a pseudo noise sequence to apply demodulated data; And (j1) detecting watermark information by summing the demodulated data for each chip rate. The method as claimed in claim 34, wherein, in step (j1), if the sum of the results in units of chip rate becomes zero, watermark information is detected using a sign of the block having the largest absolute value in the chip rate unit Wherein the copy control method is characterized by: 35. The method of claim 34, (k1) detecting copy control information by comparing the detected watermark information with a predetermined copy control information pattern, or generating information indicating that there is no watermark.