KR20140094163A - Watermarking Method and Apparatus for Inserting Watermark Created from an image into another image - Google Patents

Abstract

Provided are a watermarking method and an apparatus for inserting a watermark created from an image into another image. According to an embodiment of the present invention, a watermarking method includes creating a watermark using a first image, determining a position on a second image in which the created watermark is to be inserted, and inserting the watermark in the determined position. Accordingly, the integrity of another image can be verified by inserting a watermark created from an image into another image.

Description

TECHNICAL FIELD [0001] The present invention relates to a watermarking method and apparatus for inserting a watermark generated from an image into an image,

The present invention relates to a watermarking method and apparatus, and more particularly, to a watermarking method and apparatus for inserting a watermark in an image for integrity verification of an image or medium on which an image is recorded.

The MRTD is encrypted and stored in an IC chip / card (Integrated Circuit Chip / Card), such as passport number, English name, gender, and resident registration number corresponding to the information in the machine-readable zone (MRZ). The e-resident card (e-resident registration card) stores information such as resident registration number, address, and fingerprint on the IC chip / card.

In order to ensure interoperability, the face, fingerprint, and iris information must be stored as image prototypes. To improve the reading speed, the face and iris must be stored in JPEG or JPEG200 format And the fingerprint is compressed and stored in the WSQ format.

In the case of electronic resident cards, fingerprints are likely to be compressed into image circles and stored in the IC chip / card according to the above example of the ePassport.

However, if the IC chip / card in the ePassport is only compatible with the protocol, any reader can read and modify the information stored in the IC chip / card in the ePassport, and falsify it to create a false ePassport. This will be the same for the electronic resident card.

In particular, the identification photographs stored in the ePassport or the electronic resident card are not encrypted and stored, so the risk of forgery / alteration is higher.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method and apparatus for simultaneously providing a confidentiality of fingerprint information stored in an electronic passport or an electronic resident card, And a face image watermarking method and apparatus using a part of feature points selected from identifiable fingerprint information.

It is another object of the present invention to provide a method and apparatus for watermarking by a technique of inserting a watermark generated from an image into another image. It is still another object of the present invention to provide an integrity verification method and apparatus corresponding to the above-mentioned watermarking method and apparatus.

According to an aspect of the present invention, there is provided a watermarking method including: generating a watermark using a first image; Determining a position on a second image where the watermark generated in the generating step is to be inserted; And inserting the watermark at a position determined in the determining step.

The generating step may include extracting feature points from the first image, and generating a watermark using position information of the feature points.

The generating may further include calculating | (x-y) | s for each of the position information (x, y) of the minutiae points; And selecting a part of the calculated | (x-y) |, and generating a watermark with the selected part.

The selected part may be m (m: natural number) higher m among the calculated | (x-y) |.

The generating may further include converting a selected portion into binary digits of the same digits and arranging the converted digits to complete a watermark.

The determining step may include: generating secret key arrays by randomly generating secret keys that are not duplicated; And selecting positions of watermark bits constituting the watermark to be inserted into positions of the second image indicated by the secret keys arranged in the secret key arrangement, respectively.

Also, the selecting step may select the blocks into which the watermark bits are inserted, from among the blocks constituting the second image.

The inserting step may insert watermark bits constituting the watermark into the Y-image for the second image.

Also, the inserting step may insert the watermark bits into a portion of the AC coefficients of the Y-image.

Some of the AC coefficients into which the watermark bits are inserted may be the top n (n: natural number) having a large absolute value magnitude.

Also, the second image is divided into a plurality of blocks, and the same watermark bit may be inserted into the AC coefficients included in the same block.

In the inserting step, the watermark bit may be inserted in digits except for the largest digit and the smallest digits above the decimal point of the AC coefficients.

If the watermark bit is " 1 ", the watermark bit is set to one of an odd number and an even number. When the watermark bit is "0 ", the watermark bit is inserted The number of digits to be set can be set to either odd or even.

In the inserting step, the decimal point of the AC coefficients may be discarded, and the least significant digit of the decimal point may be set to "5 ".

In addition, the first image and the second image may be images of different body parts of the same person.

The first image may be a fingerprint image, and the second image may be a face image.

On the other hand, according to another embodiment of the present invention, a watermarking apparatus uses a first image to generate a watermark, determines a position on a second image where the generated watermark is to be inserted, And a processor And a storage unit for providing the storage space required for the process of generating the watermark, determining the position, and inserting the watermark.

On the other hand, according to another embodiment of the present invention, an integrity verification method includes: extracting watermark bits from a watermarked second image; Restoring a watermark by arranging the watermark bits in place using the watermark embedding position information; Generating a watermark from index information of a first image used to generate a watermark embedded in the second image; And comparing the watermark reconstructed in the reconstructing step with the watermark generated in the generating step to determine the integrity of the second image.

According to yet another aspect of the present invention, there is provided an apparatus for verifying integrity, comprising: extracting watermark bits from a watermarked second image and using the watermark embedding position information to return the watermark bits to the original position Generating a watermark from the index information of the first image used to generate the watermark embedded in the second image, and comparing the recovered watermark with the generated watermark, A processor for determining the integrity of the processor; And a storage unit for extracting the watermark bits, restoring the watermark, and providing a storage space necessary for the process of generating the watermark.

As described above, according to the embodiments of the present invention, it is possible to verify the integrity of another image by inserting a watermark generated from the image into another image.

In particular, in order to provide the confidentiality of the fingerprint information stored in the electronic passport and the electronic resident card IC chip / card and the integrity of the face image information, some feature points selected from the fingerprint information capable of identifying the user are extracted, It is possible to verify the integrity by inserting it into the mark.

In particular, watermark prediction or estimation is very difficult because the watermark is generated from the index information of the feature points of the fingerprint image. In addition, since the blocks into which the watermark is inserted are randomly selected, the security is excellent.

In addition, it is possible to improve the non-visibility of the watermark by making the watermark size relatively small, inserting them into the AC coefficients of the Y-image having a large data size, and inserting it into the DC coefficient.

In addition, not only the watermark is inserted using the coefficient averaging but also the watermark is robust against the image processing process or the noise input by keeping the number of digits smaller than the inserted number of the watermark to "5".

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a process of generating a watermark from a fingerprint image,
2 is a diagram illustrating a result of extracting feature points from a fingerprint image and a fingerprint image,
FIG. 3 is a diagram illustrating index information on minutiae points and a supplementary description of a watermark generating process using the index information.
4 is a view of a secret key arrangement and a watermark position change using the same,
FIG. 5 is a view showing a process of inserting a watermark into a proof photograph,
6 is a diagram illustrating a watermark bit insertion method in a block,
7 is a diagram illustrating a method for selecting AC coefficients to insert a watermark bit in a block,
8 is a diagram summarizing a watermark bit insertion technique,
Fig. 9 is a diagram provided in the description of the integrity verification process of the ID photograph stored in the IC chip / card of the ePassport;
10 is a block diagram of a MRTD according to another embodiment of the present invention,
11 is a block diagram of a MRTD examination apparatus according to another embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In a preferred embodiment of the present invention, a watermark is generated from a fingerprint image, and the generated watermark is inserted into an ID photo to be stored in an IC chip / card (Integrated Circuit Chip / Card) of the ePassport so that the integrity of the ID photo / The watermarking technique for ensuring transparency is described in detail.

1. Create a watermark

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram provided for explanation of a process of generating a watermark from a fingerprint image. FIG.

As shown in FIG. 1, first, a fingerprint image is obtained (S110) and feature points are extracted (S120). The fingerprint image is illustrated on the left side of FIG. 2, and the feature points extracted from the fingerprint image on the left side of FIG. 2 are illustrated.

The minutiae extracted in step S120 include a point where the ridge starts or ends, a divergence point where the ridge is divided, a center point where the direction of the fingerprint is suddenly changed, and a delta where the ridge is divided into three directions.

Then, the index information (coordinate information) of the minutiae points extracted in step S120 is acquired (S130). The index information acquisition result through step S130 is shown in (a) of FIG.

3, the index information (coordinate information) of the minutiae is assumed to be in the form of [x coordinate] [y coordinate], [0] [0] [255] [255].

3 (a) shows that the feature points in the fingerprint image are (12,6), (15,102), (35,201), (47,95), (56,62), Position.

The index information obtained in step S130 is matched with the MRTD number and stored in the DB of the Ministry of Justice server (S140). This is because it is used for integrity verification of the watermarked proof photograph.

In step S150, the absolute value | (x-y) | of the result of subtracting the y coordinate from the x coordinate is calculated for each of the index information obtained in step S130. In step S150, the reason for applying the subtraction operation is to prevent the calculation result from exceeding 8 bits, and the reason for taking the absolute value is to prevent the calculation result from being negative.

FIG. 3 (b) shows the result of performing step S150. As shown in FIG. 3 (b), it can be confirmed that 6, 87, 166, 48, 6, and 24 are calculated as a result of calculating | (x-y) |

Thereafter, the calculation result values calculated in step S150 are sorted in descending order (S160). At this time, for those having the same calculation result value, the calculation result value having a large x coordinate is first arranged. The alignment result in step S160 is shown in FIG. 3 (c).

Finally, in step S160, the top eight (from first to eighth) of the operation result values sorted in the descending order are selected, and the selected eight are converted into eight-digit binary numbers, 8x8) bit watermark is generated (S170). The results of converting the operation result values in step S170 into binary numbers are shown in FIG. 3 (d).

The reason for applying the above-described watermark generation method is that a significant amount (watermark information generated depending on the characteristic of the user's biometric information pattern) that provides both improvement in image reading speed and security, and a small amount (64 bits) .

2. Create secret key array and determine watermark insertion position

Up to now, the process of generating a watermark with a fingerprint image has been described in detail. Hereinafter, a technique of inserting the generated watermark into the proof photograph will be described in detail.

If the watermark is simply inserted into the ID picture, it can be easily extracted by the attacker. Therefore, in the proposed technique, secret keys are randomly generated and arranged, and the embedding positions of the watermark bits constituting the watermark are randomly determined according to the secret key arrangement.

2.1 Creating a secret key array

The secret key sequence is generated by first generating 63 random numbers and arranging the generated random numbers into secret keys. At this time, the random number can be generated as a remainder obtained by dividing the current time by 64. For example, if the current time is 13:10:7, the random number is a random number obtained by dividing the current time by 47,407 seconds (= 13 * 3600 + 10 * 60 + 7) .

At this time, the secret key generated later is not overlapped with the generated secret key first. For example, if the first generated secret key [0] is "47" and the random number generated by the second secret key [1] is also "47", the random number is regenerated to be "47" The secret key is [1]. With this principle, the random number generated by the third secret key [2] is not duplicated with the first secret key [0] and the second secret key [1].

Accordingly, 0 to 63 are randomly included in the secret key arrangement randomly once without duplication. In the center of FIG. 4, a secret key arrangement is exemplified. Meanwhile, the completed secret key arrangement information is matched with the ePass number and stored in the DB of the Ministry of Justice server. This is because it is used for integrity verification of the watermarked proof photograph.

2.2 Decide watermark embedding block by secret key arrangement

The secret key arrangement is used to determine where the watermark bits constituting the watermark are to be inserted.

Specifically, the insertion positions of the watermark bits are determined by arranging 'the 64 bits constituting the watermark generated in advance' in 'indexes (positions) indicated by the secret keys arranged in the secret key arrangement' .

Here, the index indicated by the secret key designates one of the blocks constituting the proof photograph. That is, it is understood that the watermark bit is inserted into the block at the position designated by the secret key.

The first bit "1" constituting the watermark shown on the left side of Fig. 4 is arranged at the index "47" indicated by the first secret key "Key [0]" As shown in the right side of Fig. 4, the index "47 " designates a block whose position is (8,6) among the blocks constituting the proof photograph. Therefore, the first bit "1" constituting the watermark is inserted into the (8, 6) block of the proof photograph.

Similarly, the second bit "0" constituting the watermark is inserted into the (1,6) block specified by the index "5 " indicated by the second secret key" Key [ The third bit "0" constituting the mark is inserted into the (1,8) block specified by the index "7" indicated by the third secret key "Key [2]" listed in the secret key arrangement.

3. Insert watermark

Up to now, a process of generating a watermark using a fingerprint image and generating a secret key array that can be referred to as watermark insertion position information has been described in detail. Hereinafter, a process for inserting a watermark into a proof photograph (assumed to be a 256x256 JPEG image) using a coefficient augmentation is a blind watermarking method capable of extracting a watermark without an original image, see Fig. 5 Will be described in detail.

3.1. Select watermark insertion factor

As shown in FIG. 5, first, an ID photograph is obtained, and the obtained ID photo is converted from RGB format to YCbCr format. As will be described later, the watermark is to be inserted into the Y-image, so that the proof photograph, which is a JPEG image in the RGB format, is converted into the YCbCr format.

The reason for inserting the watermark into the Y-image is that Cr or Cb has a small amount of information and color distortion may occur when the watermark is inserted, while Y has a large amount of information, This is because the invisibility of the mark is improved. Since human vision is more sensitive to brightness than color, the information amount of Y in the image is larger than the information amount of Cr or Cb.

Thereafter, the Y-image is divided into 32x32 blocks, and the DCT coefficients are aligned by DCT (Discrete Cosine Transform) on a block-by-block basis. Since the size of the Y-image is 256 × 256, it is divided into 64 (= 8 × 8) blocks.

Sixty-four bits constituting a watermark are inserted one by one in the divided 64 blocks, and the watermark bit inserted is determined by the secret key arrangement. That is, a watermark bit matched to a secret key having an index "0 " is inserted into a block whose position is (1, 1).

Referring to FIG. 4, a watermark bit "1" matched with a secret key Key [0] having an index "47 " The watermark bit "0" matched with the secret key Key [1] having the index of "5" is inserted into the (1, 6) block, and the secret key A watermark bit "0" matched to [2] is inserted.

On the other hand, the DCT block includes one DC coefficient and 1,023 AC coefficients, in which no watermark bits are inserted. Watermark bits are inserted only in 10 of these AC coefficients. The watermark bits inserted in the ten AC coefficients are the same.

FIG. 6 shows a watermark bit insertion method for a (1,1) block. As shown in FIG. 6, watermark bits are inserted only in 10 AC coefficients indicated in black in the (1,1) block.

A method for selecting AC coefficients to insert a watermark bit is shown in FIG. As shown in FIG. 7, 1,023 AC coefficients are rearranged in descending order according to the magnitude of the absolute value, and then the top 10 coefficients are selected as the AC coefficients to insert the watermark bit. That is, one of the 1,023 AC coefficients included in the block is to insert a watermark bit only in 10 AC coefficients having a large absolute value magnitude.

The DC coefficient is the most important information that represents the average value of the luminance of the block. The watermark is inserted in the DC coefficient, and the watermark bit is not inserted.

In addition, watermark nonvisibility is improved by minimizing the luminance distortion that may occur by inserting watermark bits only in 10 AC coefficients having a large absolute value among the AC coefficients.

As described above, the AC coefficients are rearranged and the top 10 watermarks are inserted by selecting the upper 10 coefficients having a large coefficient size because the watermark is inserted into a large value of the AC coefficient value to protect the watermark against the image attack such as JPEG compression It is more likely.

3.2 Selected AC  Insert watermark bits into coefficients

Hereinafter, a method of inserting watermark bits into the previously selected 10 AC coefficients will be described in detail. In the proposed method, we use blind watermarking using coefficient averaging.

The position where the watermark bit is inserted in the AC coefficient is 10 digits. If the watermark bit is inserted into the 100-digit number, luminance distortion may occur. When the watermark bit is inserted into the 1-digit number, the watermark bit itself may be distorted due to the image processing process or noise input. (The number of digits except the largest digit and the smallest digits above the decimal point) is selected as the position where the watermark bit is inserted.

Specifically, when the watermark bit is "0 ", the watermark is inserted in such a manner that the 10th digit of the AC coefficient becomes an even number and the 10th digit of the AC coefficient becomes an odd number when the watermark bit is" 1 & .

For this, when the watermark bit is "0", if the 10th digit of the AC coefficient is an odd number, the digit number of 10 is incremented by one (10 is added if the AC coefficient is positive (+10) Subtraction (-10)) to an even number.

This is to prevent an absolute value ranking of the AC coefficient from being changed in the process of inserting the watermark, thereby preventing an error in the process of extracting a watermark to be described later. For example, when 10 is added to the AC coefficient "-100" and converted to "-90", the absolute value is reduced and a problem may occur in which the selection of the upper 10 AC coefficients performed in the extraction of the watermark is omitted have.

On the contrary, if the watermark bit is "1", if the 10th digit of the AC coefficient is an even number, the digit number of 10 is incremented by one (10 is added (+10) if the AC coefficient is positive and 10 is subtracted -10)) to convert to an odd number.

On the other hand, the 1 digit of the AC coefficient into which the watermark bit is inserted is fixed to "5 ", and the decimal point is discarded. The reason why the 1 digit of the AC coefficient is fixed to "5" is that when the number of digits of 1 is "9" or "1 ", 10 digits are increased or decreased by the image processing process or noise input, This is to prevent the mark bit from being distorted.

8, the watermark bit inserting technique described above is specifically divided and summarized.

3.3 Watermarked photographic records

When the watermark bit insertion is completed for all the blocks constituting the Y-image by the above-described method, the Y-image is IDCT as shown in the middle of FIG. 5, and the proof photograph of the YCbCr format is the proof Converts the image into a photograph, and generates a watermarked proof photograph. The watermarked proof photograph is recorded on the IC chip / card of the MRTD (P).

4. Identification Photo Integrity Verification

In the following description, the watermarked proof photographs recorded on the IC chip / card of the MRTD P shown in Fig. 5 are read through the RF reader (R) The process of performing the integrity verification of the watermarked proof photograph by receiving the index information and the secret key arrangement information of the minutiae points of the fingerprint image will be described in detail with reference to FIG.

As shown in FIG. 9, first, the watermarked proof photograph stored in the IC chip / card of the ePassport is read (S205). Then, the read watermarked proof photograph is converted from the RGB format to the YCbCr format (S210).

Next, the Y-image of 256 × 256 size is divided into 32 × 32 blocks and DCT is performed on a block-by-block basis (S215), and the AC coefficients are rearranged in ascending order according to the absolute value size for each 64 blocks (S220) . Then, watermark bits are read with reference to the top 10 AC coefficients for each 64 blocks, and a 64-bit watermark is extracted (S225).

Specifically, the watermark bit determination in step S225 is performed with reference to the 10-digit digits of the top 10 AC coefficients. When the number of odd number is large, the watermark bit is determined as "1 &Quot; 0 ".

Thereafter, the secret key arrangement is received from the DB (D) through the server S (S230), and the watermark bits extracted in step S225 are rearranged with reference to the secret key arrangement (S235). The in-situ array in step S235 can be understood as a process of returning the watermark array shown on the right side of FIG. 4 to the watermark array shown on the left side of FIG. 4 with reference to the secret key array shown in the center of FIG.

Next, in step S235, the watermark in which the watermark bits are arranged in the original order is converted into a decimal number in 8 bits, and the watermark is restored (S240).

Then, the index information is received from the DB (D) through the judicial affairs server S (S245), and | (x-y) | is calculated for each index information (S250). The index information received in step S245 is the index information (coordinate information) of the minutiae points extracted from the fingerprint image when the watermark is generated.

Thereafter, the calculation result values calculated in step S250 are sorted in descending order (S255), and the upper eight calculation result values are selected (S260).

Finally, the result of step S240 is compared with the result of step S260, and if the two match, it is determined that the integrity of the proof image stored in the IC chip / card of the ePassport is secured (S265).

If the result of step S240 and the result of step S260 do not match, the proof photograph or ePassport may be treated as falsified or altered.

5. MRTD Recording Device

10 is a block diagram of a MRTD according to another embodiment of the present invention. The illustrated MRTD 300 is an apparatus for recording passport information, a fingerprint image of a user, and a proof photograph watermarked according to the above technique, on an IC chip / card provided in the user's passport P. In the recording process, the MRTD 300 also functions as a watermarking device.

10, the MRTD 300 for performing such functions includes a display 310, an RF writer 320, a processor 330, a communication interface 340, and a storage unit 350, Respectively.

The display 310 displays the fingerprint image, the proof photograph, the passport information, the recording completion guidance message, and the like, which are time information provided while the MRTD 300 is operating.

The RF writer 320 can read passport information, a fingerprint image, and a watermarked proof photograph on an IC chip / card provided in the electronic passport P, as well as information and images recorded on the IC chip / card .

The processor 330 generates a watermark from the fingerprint image according to the watermarking technique shown in Figs. 1 to 8, and inserts the generated watermark into the proof photograph.

The communication interface 340 transmits the index information about the minutiae points of the fingerprint image and the secret key arrangement information generated in the watermarking process by the processor 330 to the DB D through the Ministry of Justice server S .

The storage unit 350 is a storage medium that provides a storage space necessary for the watermarking process by the processor 330.

6. The ePassport control device

11 is a block diagram of a MRTD examination apparatus according to another embodiment of the present invention. The illustrated MRTD device 400 is a device for reading passport information, a fingerprint image, and an ID photograph from an IC chip / card provided in the MRTD to provide it to immigration control or immigration control. In the examination process, the MRTD examination apparatus 400 according to the present embodiment also functions as an integrity verification apparatus.

11, the MRTD examination apparatus 400 that performs the above function includes a display 410, an RF reader 420, a processor 430, a communication interface 440, and a storage unit 450, Respectively.

The RF reader 420 reads the passport information, the fingerprint image and the watermarked proof photograph recorded on the IC chip / card in the ePassport P of the outgoing / incoming person.

The display 410 is time information for immigration control of the immigration manager. The display 410 includes passport information read by the RF reader 420, a fingerprint image, a watermarked ID photograph, an integrity verification result (whether the MRTD / ).

The processor 430 performs integrity verification of the watermarked proof photograph according to the proof photo integrity verification technique shown in Fig.

The communication interface 440 receives from the DB D the index information about the minutiae points of the fingerprint image and the secret key arrangement information necessary for the integrity verification process by the processor 430 through the Ministry of Justice server S And transfers it to the processor 430.

The storage unit 450 is a storage medium that provides the storage space necessary for the integrity verification process by the processor 430. [

7. Variation example

Up to now, a watermarking technique for generating a watermark from a fingerprint image and inserting it into a proof photograph has been described in detail with a preferred embodiment.

The ePassport referred to in the above embodiment is a kind of a medium for storing digital images such as fingerprint information and proof photographs. Even when the ePassport is replaced with an 'electronic resident card' or 'another medium for storing digital images' It goes without saying that the invention can be applied.

Also, the server / DB of the Ministry of Justice mentioned in the above embodiments can be replaced with a server / DB of another organization or company depending on the type of service and system to which the technical idea of the present invention is applied.

In addition, the fingerprint image and the ID photograph shown in the above embodiments exemplify images. When a watermark is generated from an image other than a fingerprint image and a watermark is inserted into an image other than the ID photo, Technical ideas are applicable.

At this time, there is no limitation on the type of image. The image may be an image irrelevant to the human body, and the technical idea of the present invention may also be applied to a case where a watermark is inserted into an image document (including an official document and an apostrophe).

It goes without saying that the technical idea of the present invention can also be applied to a computer-readable recording medium having a computer program for performing the functions of the apparatus and method according to the present embodiment. In addition, the technical idea according to various embodiments of the present invention may be embodied in computer-readable code form recorded on a computer-readable recording medium. The computer-readable recording medium is any data storage device that can be read by a computer and can store data. For example, the computer-readable recording medium may be a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical disk, a hard disk drive, or the like. In addition, the computer readable code or program stored in the computer readable recording medium may be transmitted through a network connected between the computers.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention.

P: ePassport
R: Leader
S: Server
D: DB (DataBase)

Claims (19)

Generating a watermark using the first image;
Determining a position on a second image where the watermark generated in the generating step is to be inserted; And
And inserting the watermark at a position determined in the determining step.
The method according to claim 1,
Wherein the generating comprises:
Extracting feature points from the first image,
And generating a watermark with the position information of the minutiae points.
3. The method of claim 2,
Wherein the generating comprises:
Calculating (xy) | for each of the position information (x, y) of the feature points; And
Selecting some of the calculated | (xy) | values,
And a watermark is generated as a selected portion.
The method of claim 3,
The selected portion may include,
(M: natural number) among the calculated | (xy) | s that are large in magnitude.
The method of claim 3,
Wherein the generating comprises:
And converting the selected portion into binary digits of the same digits and arranging the selected digits to complete the watermark.
The method according to claim 1,
Wherein,
Generating secret key arrays by randomly generating secret keys that are not duplicated; And
And selecting positions of watermark bits constituting the watermark at positions of the second image indicated by the secret keys arranged in the secret key arrangement, respectively.
The method according to claim 6,
Wherein the selecting step comprises:
Wherein the blocks to be embedded with the watermark bits are selected from the blocks constituting the second image.
The method according to claim 1,
In the inserting step,
And inserting the watermark bits constituting the watermark into the Y-image for the second image.
9. The method of claim 8,
In the inserting step,
And inserting the watermark bits into a portion of the AC coefficients of the Y-image.
10. The method of claim 9,
Some of the AC coefficients into which the watermark bits are inserted,
(N is a natural number) having a large absolute value magnitude.
10. The method of claim 9,
Wherein the second image is divided into a plurality of blocks,
Wherein the same watermark bit is inserted in the AC coefficients included in the same block.
10. The method of claim 9,
In the inserting step,
Wherein a watermark bit is inserted in digits other than the largest digit and the smallest digit of decimal places of the AC coefficients.
13. The method of claim 12,
In the inserting step,
When the watermark bit is "1 ", the number of digits into which the watermark bit is inserted is set to one of an odd number and an even number, and when the watermark bit is" 0 & And the other is set to the other.
13. The method of claim 12,
In the inserting step,
Wherein the decimal point of the AC coefficients is discarded, and the least significant digit on the decimal point is set to "5 ".
The method according to claim 1,
Wherein the first image and the second image are < RTI ID = 0.0 >
And images of different body parts of the same person.
16. The method of claim 15,
Wherein the first image is a fingerprint image,
Wherein the second image is a face image.
A processor for generating a watermark using the first image, determining a position on the second image to be inserted with the generated watermark, and inserting the watermark at the determined position; And
And a storage unit for storing the watermark information, the watermark information, the watermark information, and the storage space necessary for the process of generating the watermark, determining the position, and inserting the watermark.
Extracting watermark bits from the watermarked second image;
Restoring a watermark by arranging the watermark bits in place using the watermark embedding position information;
Generating a watermark from index information of a first image used to generate a watermark embedded in the second image; And
And comparing the watermark reconstructed in the reconstructing step with the watermark generated in the generating step to determine the integrity of the second image.
Extracts watermark bits from the watermarked second image, restores the watermark by arranging the watermark bits in place using the insertion position information of the watermark, and generates a watermark embedded in the second image A processor for generating a watermark from the index information of the first image used to compare the reconstructed watermark with the generated watermark to determine the integrity of the second image; And
And a storage unit for extracting the watermark bits, restoring the watermark, and providing a storage space necessary for the process of generating the watermark.

Images