U.S. patent application number 11/712435 was filed with the patent office on 2007-08-02 for apparatus and method for preventing illegal distribution of digital contents by using a fingerprinting technique.
This patent application is currently assigned to Electronics and Telecommunications Research Institute. Invention is credited to Sanghyun Joo, Won Gyum Kim, Chang Soon Park, Yong-Seok Seo.
Application Number | 20070177763 11/712435 |
Document ID | / |
Family ID | 32822495 |
Filed Date | 2007-08-02 |
United States Patent
Application |
20070177763 |
Kind Code |
A1 |
Joo; Sanghyun ; et
al. |
August 2, 2007 |
Apparatus and method for preventing illegal distribution of digital
contents by using a fingerprinting technique
Abstract
An apparatus and method for preventing illegitimate distribution
of digital contents on Internet obtains a first wavelet image
having a user information-embedding region by performing a wavelet
transformation (WT). The user information embedding region of the
first wavelet image is wavelet-transformed to obtain a second
wavelet image composed of a discrete cosine (DC) region and
high-frequency regions second wavelet image. A high-frequency
components removed image is obtained by removing high-frequency
components in the high-frequency regions of the second wavelet
image, and subjected to an inverse WT (IWT) to be outputted as an
IWT image. A user information embedding unit embeds user
information to the IWT image, wherein data of the user information
are sequentially embedded to positions where a difference value
between the user information embedding region and the new user
information embedding region is small, to thereby reset the user
information embedding region as the user information.
Inventors: |
Joo; Sanghyun; (Daejeon,
KR) ; Kim; Won Gyum; (Daejeon, KR) ; Seo;
Yong-Seok; (Daejeon, KR) ; Park; Chang Soon;
(Daejeon, KR) |
Correspondence
Address: |
LOWE HAUPTMAN BERNER, LLP
1700 DIAGONAL ROAD
SUITE 300
ALEXANDRIA
VA
22314
US
|
Assignee: |
Electronics and Telecommunications
Research Institute
|
Family ID: |
32822495 |
Appl. No.: |
11/712435 |
Filed: |
March 1, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10648517 |
Aug 27, 2003 |
|
|
|
11712435 |
Mar 1, 2007 |
|
|
|
Current U.S.
Class: |
382/100 ;
382/276 |
Current CPC
Class: |
G06T 2201/0063 20130101;
G06T 1/005 20130101; G06T 2201/0083 20130101; G06T 2201/0081
20130101; G06T 2201/0052 20130101 |
Class at
Publication: |
382/100 ;
382/276 |
International
Class: |
G06K 9/00 20060101
G06K009/00; G06K 9/36 20060101 G06K009/36 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 23, 2002 |
KR |
2002-64922 |
Claims
1-14. (canceled)
15. An apparatus for preventing illegitimate distribution of
digital contents on Internet by employing a fingerprinting
technique, comprising: a first wavelet image obtained by performing
a wavelet transformation (WT) to an original image of the digital
contents, wherein the first wavelet image has a user information
embedding region; a second wavelet image obtained by performing a
WT to the user information embedding region of the first wavelet
image, wherein the second wavelet image composed of a discrete
cosine (DC) region and high-frequency regions; a high-frequency
components removed image composed of the DC region and regions
obtained by removing high-frequency components in the
high-frequency regions of the second wavelet image, i.e., by
setting high-frequency components other than the DC as "0", and
subjected to an inverse WT (IWT) to be outputted as an IWT image;
and a user information embedding unit for embedding user
information, which is provided from an operator, to the IWT image,
thereby obtaining a user information embedded image with a new user
information embedding region, and embedding the user information to
a position determined by a random sequence generated from a
location key in a blind information embedding system which does not
use the first wavelet image, to thereby reset the user information
embedding region as the new user information embedding region.
16. The apparatus of claim 15, wherein the random sequence
[locat(K) .epsilon.{0,1}, 1.ltoreq.k.ltoreq.S(LL.sub.n)] is set to
have a probability defined in the following equation and wherein
the user information is embedded to a position corresponding to "1"
of the random sequence, LLn being a user information embedding
region: P(1)=ui.sub.--len/S(LL.sub.n)
P(0)=1-ui.sub.--len/S(LL.sub.n).
17. The apparatus of claim 16, wherein ui_len and S(LL.sub.n)
respectively represent the size of LL.sub.n and the user
information.
18. A method for preventing illegitimate distribution of digital
contents on Internet comprising the steps of: performing a WT to an
original image to obtain a first wavelet image; determining a user
information-embedding region in the first wavelet image and
performing a WT to the user information-embedding region, thereby
obtaining a second wavelet image; removing high-frequency
components from the second wavelet image by setting regions other
than the user information-embedding region of a discrete cosine
(DC) as "0", thereby obtaining a high frequency components removed
image and performing an inverse WT (IWT) to the high-frequency
components removed image, thereby obtaining an IWT image; embedding
user information and a location key provided from an operator to
the IWT image to obtain a user information embedded image, thereby
obtaining a user information embedded image with a new user
information embedding region; and embedding the user information to
a position determined by a random sequence generated from a
location key in a blind information embedding system which does not
use the first wavelet image, to thereby reset the user information
embedding region as the user information.
19. The method of claim 18, wherein the random sequence [locat(K)
.epsilon.{0,1}, 1.ltoreq.k.ltoreq.S(LL.sub.n)] is set to have a
probability defined in the following equation and wherein the user
information is embedded to a position corresponding to "1" of the
random sequence, LLn being a user information embedding region:
P(1)=ui.sub.--len/S(LL.sub.n) P(0)=1-ui.sub.--len/S(LL.sub.n).
20. The method of claim 18, wherein ui_len and S(LL.sub.n)
respectively represent the size of LL.sub.n and the user
information.
21. The method of claim 16, wherein ui_len and S(LL.sub.n)
respectively represent the size of LL.sub.n and the user
information.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional of U.S. Ser. No.
10/648,517, filed on Aug. 27, 2003. This application, in its
entirety, is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to an apparatus and method for
preventing illegal distribution of digital contents by using a
fingerprinting technique; and, more particularly, to an apparatus
and method for preventing illegitimate distribution of digital
contents by using a fingerprinting technique which allows to embed
purchaser information to the digital contents, sold through an
electronic commercial activity, in the form of a watermark.
BACKGROUND OF THE INVENTION
[0003] In general, recent increase of illegitimate copying and
purchase of digital contents through the use of Internet has
intensified a demand for a technology capable of protecting
intellectual property.
[0004] Unlike off-line contents, digital contents on the web can be
easily copied and distributed all through the Internet. Thus,
various technologies have been developed in order to protect
intellectual property in the Internet environment. Among such
technologies, there exist an encryption system, an access control
system and a copyright marking system.
[0005] The encryption system and the access control system,
however, are rarely utilized in recent years since they have a
defect that contents can be illegally copied after being legally
decoded.
[0006] On the other hand, the copyright marking system is gaining
popularity since it employs a technique for directly embedding
information to a media itself and, thus, can provide legal evidence
in case a litigation for a literary piracy occurs, thereby
contributing to finding out a copyright holder and an illegitimate
distributor of contents.
[0007] More specifically, the copyright marking technology can be
classified into a watermarking technique, a fingerprinting
technique, etc.
[0008] The watermarking technique is used to prove only the
property of contents by embedding information of an owner of the
property to contents. Since, however, the same information, i.e.,
the owner information, is uniformly embedded to digital contents to
be sold, all of the watermark embedded digital contents are
undistinguishable from each other. For the reason, the watermarking
technique is considered as a passive way to protect the
property.
[0009] The fingerprinting technique, on the other hand, serves to
find out a re-distributor of illegally copied contents by embedding
information of a legitimate purchaser to the contents.
Fingerprinted contents can be distinguished from each other since
it is purchaser information, not property owner information, which
is embedded to the digital contents. Therefore, the fingerprinting
technique is a more active way of protecting intellectual property
than the watermarking technique.
[0010] The fingerprinting technique involves three steps of
generating, embedding and extracting user information by using an
encryption protocol. The user information is embedded to contents
by using a user key of a purchaser of the contents and the user key
information is preserved in order to use later to trace a
distributor of illegal copies of the contents.
[0011] Further, there is prepared a registration center (RC)
between a seller and a purchaser, which takes charge of generating
and embedding a user key, i.e., seller information, thereby
allowing to obtain evidence of an illegal purchaser of illegally
copied contents, if any.
[0012] However, the conventional technologies using the encryption
protocol as described above have a defect in that digital contents
can be illegally copied after being legally decoded and, further, a
new user key can be generated by colluding user keys which have
been respectively allotted to individual purchasers. Furthermore,
since the fingerprinting technique using the encryption protocol is
time-consuming in performing an embedding process due to its use of
the encryption protocol, a quality of service (QOS) may be
deteriorated in view of the fact that an e-purchase on the Internet
should be processed on a real time basis.
[0013] In Eurocrypt97 (1997), there is disclosed a technology for
preventing illegitimate distribution of contents by using such a
conventional fingerprinting system, entitled "Anonymous
Fingerprinting".
[0014] The anonymous fingerprinting is a fingerprinting technique
using an encryption protocol. Purchaser information is attached to
purchased contents. Thus, if the contents are illegally copied and
distributed, a legitimate purchaser can be distinguished from
illegitimate purchasers by extracting the purchaser information
that has been embedded to the contents earlier.
[0015] To be more specific, a purchaser of certain contents
registers his own purchaser information at a certified registration
center. Then, the registered purchaser information is fingerprinted
to the contents. A seller generates purchase information including
the purchaser information registered at the registration center
and, then, embeds to the sold contents the generated purchase
information. Then, the seller distributes the purchase information
embedded contents after encrypting the contents by using a user's
key. If a redistributed content is founded, the seller extracts the
embedded information from the redistributed content and sends the
extracted information to the registration center to identify the
legitimate purchaser of the contents.
[0016] In other words, the purchaser information serves as a single
fingerprinting data to identify the purchaser. The purchaser
information is embedded to contents when the contents are
purchased. This system, however, does not specify where to embed
the purchaser information but just suggests a simple transaction
method between a seller and a purchaser, which uses an encryption
technique.
[0017] Further, since multimedia data such as image and audio data
is redistributed in a decoded state unlike general software, it is
impossible to maintain the purchaser information as fingerprinting
information. Therefore, another type of fingerprinting embedding
and extraction technique is required in order to use the purchaser
information as a fingerprinting data for the multimedia data such
as image and audio data.
[0018] As described above, the prior-art technologies for
protecting intellectual property exhibit drawbacks in that digital
contents can be illegally copied after being legally decoded by
making use of an encryption technique and, further, a new user key
can be generated by colluding user keys already allotted to
purchasers.
SUMMARY OF THE INVENTION
[0019] It is, therefore, an object of the present invention to
provide an apparatus and method for preventing illegitimate
redistribution of digital contents by employing a non-blind and a
blind fingerprinting technique.
[0020] In accordance with one aspect of the invention, there is
provided an apparatus for preventing illegitimate distribution of
digital contents on Internet by employing a fingerprinting
technique, including: a first wavelet image obtained by performing
a wavelet transformation (WT) to an original image of the digital
contents, wherein the first wavelet image has a user information
embedding region; a second wavelet image obtained by performing a
WT to the user information embedding region of the first wavelet
image, wherein the second wavelet image composed of a discrete
cosine (DC) region and high-frequency regions; a high-frequency
components removed image composed of the DC region and regions
obtained by removing high-frequency components in the
high-frequency regions of the second wavelet image, i.e., by
setting high-frequency components other than the DC as "0", and
subjected to an inverse WT (IWT) to be outputted as an IWT image;
and a user information embedding unit for embedding user
information, which is provided from an operator, to the IWT image,
thereby obtaining a user information embedded image with a new user
information embedding region, comparing the user information
embedding region of the first wavelet image with the new user
information embedding region of the user information embedded
image, and embedding the new user information to positions where a
difference value between the user information embedding region and
the new user information embedding region is small while minimizing
a size change of the user information embedding region, to thereby
reset the user information embedding region as the new user
information.
[0021] In accordance with another aspect of the invention, there is
provided a method for preventing illegitimate distribution of
digital contents on Internet, including the steps of: performing a
WT to an original image to obtain a first wavelet image;
determining a user information embedding region in the first
wavelet image and performing a WT to the user information embedding
region, thereby obtaining a second wavelet image; removing
high-frequency components from the second wavelet image by setting
regions other than the user information embedding region of a
discrete cosine (DC) as "0", thereby obtaining a high-frequency
components removed image and performing an inverse WT (IWT) to the
high-frequency components removed image, thereby obtaining an IWT
image; embedding user information provided from an operator to the
IWT image to obtain a user information embedded image, comparing a
user information embedding region of the user information embedded
image with the user information embedding region and resetting the
user information embedding region as a new user information
embedding region LL.sub.1, which is determined by a length and an
embedding intensity of a data sequence of the user information in
order to minimize deterioration of image quality; and embedding the
user information to a position where a difference value between the
user information embedding region and the new user information
embedding region is small.
[0022] In accordance with still another aspect of the invention,
there is provided an apparatus digital contents on Internet by
employing a fingerprinting technique, including: a first wavelet
image obtained by performing a wavelet transformation (WT) to an
original image of the digital contents, wherein the first wavelet
image has a user information embedding region; a second wavelet
image obtained by performing a WT to the user information embedding
region of the first wavelet image, wherein the second wavelet image
composed of a discrete cosine (DC) region and high-frequency
regions; a high-frequency components removed image composed of the
DC region and regions obtained by removing high-frequency
components in the high-frequency regions of the second wavelet
image, i.e., by setting high-frequency components other than the DC
as "0", and subjected to an inverse WT (IWT) to be outputted as an
IWT image; and a user information embedding unit for embedding user
information, which is provided from an operator, to the IWT image,
thereby obtaining a user information embedded image with a new user
information embedding region, and embedding the new user
information to a position determined by a random sequence generated
from a location key in a blind information embedding system which
does not use the first wavelet image, to thereby reset the user
information embedding region as the new user information.
[0023] In accordance with still another aspect of the invention,
there is provided a method for preventing illegitimate distribution
of digital contents on Internet including the steps of: performing
a WT to an original image to obtain a first wavelet image;
determining a user information embedding region in the first
wavelet image and performing a WT to the user information embedding
region, thereby obtaining a second wavelet image; removing
high-frequency components from the second wavelet image by setting
regions other than the user information embedding region of a
discrete cosine (DC) as "0", thereby obtaining a high-frequency
components removed image and performing an inverse WT (IWT) to the
high-frequency components removed image, thereby obtaining an IWT
image; embedding user information and a location key provided from
an operator to the IWT image to obtain a user information embedded
image, thereby obtaining a user information embedded image with a
new user information embedding region; and embedding the new user
information to a position determined by a random sequence generated
from a location key in a blind information embedding system which
does not use the first wavelet image, to thereby reset the user
information embedding region as the new user information.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The above and other objects and features of the present
invention will become apparent from the following description of
preferred embodiments given in conjunction with the accompanying
drawings, in which:
[0025] FIG. 1 shows a non-blind information embedding apparatus in
accordance with the present invention;
[0026] FIG. 2 is a flowchart describing operations of the non-blind
information embedding apparatus in accordance with the present
invention;
[0027] FIG. 3 illustrates a blind information embedding apparatus
in accordance with the present invention; and
[0028] FIG. 4 offers a flowchart explaining operations of the blind
information embedding apparatus in accordance with the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] Referring to FIG. 1, there is provided a non-blind
information embedding apparatus in accordance with the present
invention. After inputted to the non-blind information embedding
apparatus, an original image S1 is subjected to a first-order
wavelet transformation (WT) to be outputted as a first wavelet
image S2. LL.sub.1 of the first wavelet image S2 is set as a user
information-embedding region and is subjected again to a
first-order wavelet transformation (WT) to be outputted as a second
wavelet image S3. Subsequently, high-frequency components are
removed from the second wavelet image S3, i.e., regions other than
the region LL.sub.1 of a discrete cosine (DC) are all set to have a
value of "0", thereby obtaining a high-frequency components removed
image S4 composed of LL.sub.2 serving as a DC region and HL.sub.2,
LH.sub.2, and HH.sub.2 respectively set to be "0". The
high-frequency components removed image S4 is undergone through an
inverse WT (IWT), thereby obtaining an IWT image S4' (not shown).
Then, user information (UI) S5 provided from an operator (not
shown) is embedded to the IWT image S4' to thereby generate a UI
embedded image S6. The UI embedded image S6 has a new UI embedding
region LL.sub.2'. The new UI embedding region LL.sub.2' of the UI
embedded image S6 is compared with LL.sub.1 of the first wavelet
image in size and LL.sub.1 is reset as LL.sub.1' which is
determined by a length and an embedding intensity of a data
sequence of the UI S5 in order to minimize deterioration of image
quality, LL1' being located in a watermark embedded wavelet image
S2' (not shown) corresponding to the first wavelet image S2.
[0030] At this time, the user information S5 is embedded to where
the size difference between LL.sub.1 and LL.sub.1' is small in
order to minimize a size change of LL.sub.1. To be more specific,
values corresponding to |LL.sub.1-LL.sub.1'| are arranged according
to the order of size and data of the user information S5 are
sequentially embedded to positions of the arranged values in a
magnitude order, starting from where a difference value between
LL.sub.1(p) and LL.sub.1'(p) is smallest, wherein LL.sub.1(p)
represents a pth position of LL.sub.1 and LL.sub.1'(p) refers to a
pth position of LL.sub.1' corresponding to the pth position of
LL.sub.1. Thereafter, the watermark embedded wavelet image S2' is
undergone through an inverse WT (IWT), thereby obtaining a
watermark embedded image S7.
[0031] Referring to FIG. 2, there are described operations of the
non-blind information embedding apparatus in accordance with the
present invention.
[0032] First, an original image S1 is subjected to a first-order WT
to be outputted as a first wavelet image S2 and user information S5
is embedded into a wavelet DC region LL.sub.1 (Step 201). The order
number of the wavelet transformation should be carefully selected
since it determines the size of the DC region.
[0033] The DC region can include the largest amount of the user
information S5 when it has a size equal to that of the original
image S1. If an n-order WT is performed for an image having a size
of M.times.N, the region LL.sub.1 to which the user information S5
is to be embedded can be determined from the following Eq. 1. size
.function. ( LL n ) = M 2 n .times. N 2 n Eq . .times. 1
##EQU1##
[0034] At this time, it is preferable that the size of the region
LL.sub.1 is determined by considering a length and an embedding
intensity of the data sequence of the user information S5, and a
degree of image deterioration due to the embedding of the user
information S5 data sequence.
[0035] After the step 201 is completed, the user information
embedding region LL.sub.1 of the first wavelet image S2 is
subjected to a first-order wavelet transformation (WT) again to be
outputted as a second wavelet image S3 having sub bands of
LL.sub.2, LH.sub.2, HL.sub.2 and HH.sub.2 (Step 202).
[0036] Thereafter, high-frequency components are removed from the
second wavelet image S3 by setting regions other than the region
LL.sub.1 of a discrete cosine (DC) as "0", thereby obtaining a
high-frequency components removed image S4 composed of LL.sub.2
serving as a DC region and LH.sub.2, HL.sub.2 and HH.sub.2,
respectively set to be "0" (Step 203). The high-frequency
components removed image S4 is undergone through an IWT, thereby
obtaining an IWT image S4' (Step 204).
[0037] Subsequently, user information S5 provided from an operator
is embedded to the IWT image S4', whereby a user information
embedded image S6 is obtained. Then, a user information embedding
region LL.sub.2' of the user information embedded image S6 is
compared in size with the user information embedding region
LL.sub.1 in order to reset the LL.sub.1 as LL.sub.1' which is
determined by a length and an embedding intensity of a data
sequence of the user information S5 in order to minimize
deterioration of image quality (Step 205).
[0038] Positions of LL.sub.1' to which data of the user information
S5 is embedded are determined by comparing components of
LL.sub.1(p) and LL.sub.1' (p), wherein LL.sub.1(p) represents a PTH
position of LL.sub.1 and LL.sub.1' (p) refers to a pth position of
LL.sub.1' (Step 206).
[0039] If a component of LL.sub.1(p) is larger than that of
LL.sub.1' (p), LL.sub.1(p) is considered as +1 (Step 207) while if
a component of LL.sub.1(p) is smaller than that of LL.sub.1'(p),
LL.sub.1(P) is regarded as -1 (Step 208).
[0040] In other words, since LL.sub.1' is obtained from LL.sub.1,
the size of LL.sub.1 should be properly adjusted to satisfy the
binary information. At this time, it is notable that an enough
distance K should be secured between LL.sub.i and LL.sub.i' because
the value of a DC region, e.g., LL.sub.i, can be changed by an
arbitrary attack. The distance K is a variable that serves to
determine the embedding intensity of the user information S5. The
distance K should be set to have a proper value by considering the
fact that if the distance value K is too big or is changed too
often, the image quality may be greatly deteriorated.
[0041] As such, it is the most efficient way to embed the user
information S5 to a position where a difference value between
LL.sub.1(p) and LL.sub.1'(p) is found to be small since this way
enables to minimize a size change of LL.sub.1. Specifically, values
corresponding to |LL.sub.1-LL.sub.1'| are arranged according to the
order of size and data of the user information S5 are sequentially
embedded to positions of the arranged values in a magnitude order,
starting from where a difference value between LL.sub.1(p) and
LL.sub.1'(p) is smallest. By performing a series of user
information embedding processes described above repeatedly
(experiments shows, e.g., ten times is preferable), deterioration
of image quality can be greatly reduced (Step 209).
[0042] Referring to FIG. 3, there is shown a blind information
embedding apparatus in accordance with the present invention. An
inputted original image is subjected to a first-order WT to be
outputted as a first wavelet image S2. LL.sub.1 of the first
wavelet image S2 is set as a user information-embedding region and
is subjected again to a first-order WT, thereby obtaining a second
wavelet image S3. Subsequently, high-frequency components are
removed from the second wavelet image S3, i.e., regions other than
the region LL.sub.1 of a discrete cosine (DC) are all set to have a
value of "0", thereby obtaining a high-frequency components removed
image S4 composed of LL.sub.2 serving as a DC region and HL.sub.2,
LH.sub.2 and HH.sub.2 respectively set to be "0". The
high-frequency components removed image S4 is subjected to an
inverse Wt (IWT), thereby obtaining an IWT image S4' (not shown).
Then, user information (UI) S5 and a location key S8 provided from
an operator (not shown) are embedded to the IWT image S4', thereby
generating a UI embedded image S6 having a new UI embedding region
LL.sub.2'. Thereafter, the new UI embedding region LL.sub.2' of the
UI embedded image S6 is compared with LL.sub.1 in size. LL.sub.1 is
reset as LL.sub.1', which is determined by a length and an
embedding intensity of a data sequence of the user information in
order to minimize deterioration of image quality, LL.sub.1'
existing in a watermark embedded wavelet image S2' (not shown)
corresponding to the first wavelet image S2.
[0043] In the meanwhile, since it is impossible to arrange the
values |LL.sub.1-LL.sub.1'| according to the size order in the
blind information embedding apparatus which does not use the first
wavelet image S2, the embedding positions of the user information
S5 and the location key S8 are determined arbitrarily to minimize
deterioration of the image quality. The wavelet image S2' in which
a watermark is embedded through the user information embedding
processes as described above is undergone through an IWT, thereby
attaining a watermark embedded image S7.
[0044] FIG. 4 shows a flowchart describing operations of the blind
information embedding apparatus in accordance with the present
invention.
[0045] First, an original image S1 is subjected to a first-order WT
to be outputted as a first wavelet image S2 and user information S5
is embedded into a wavelet DC region LL.sub.1 (Step 401). The order
number of the wavelet transformation should be carefully selected
since it determines the size of the DC region.
[0046] The DC region can accommodate the largest amount of the user
information S5 when it has a size equal to that of the original
image S1. If an n-order WT is performed for an image having a size
of M.times.N, the region LL.sub.1 to which the user information S5
is to be embedded can be determined from the Eq. 1 described
above.
[0047] At this time, it is preferable that the size of the region
LL.sub.1 is determined by considering the length and the embedding
intensity of the data sequence of the user information S5, and a
degree of image deterioration due to the embedding of the user
information S5 data sequence.
[0048] As described before, the user information embedding region
LL.sub.1 of the first wavelet image S2 is subjected to a
first-order wavelet transformation (WT) again to be outputted as a
second wavelet image S3 having sub bands of LL.sub.2, LH.sub.2,
HL.sub.2 and HH.sub.2 (Step 402).
[0049] Thereafter, high-frequency components are removed from the
second wavelet image S3 by setting regions other than the region
LL.sub.1 of DC as "0" (Step 403) and thus obtained high-frequency
components removed image S4 composed of LL.sub.2 serving as a DC
region and LH.sub.2, HL.sub.2 and HH.sub.2 respectively set to be
"0" is subjected to an IWT (Step 404).
[0050] Afterwards, user information S5 and a location key provided
from an operator are embedded to the IWT image S4', whereby a user
information embedded image S6 is obtained. Then, a user information
embedding region LL.sub.2' of the user information embedded image
S6 is compared with the user information embedding region LL.sub.1
in size in order to reset the LL.sub.1 as LL.sub.1' which is newly
determined by considering a length and an embedding intensity of
the user information S5, which are found to be the most suitable
for minimizing deterioration of image quality (Step 405).
[0051] Since it is impossible to arrange the values
|LL.sub.1(12)-LL.sub.1'| according to the size order in the blind
information embedding system which does not use the first wavelet
image S2, the embedding position of the user information S5 is
determined by a random sequence generated from the location key S8
in order to minimize deterioration of the image quality (Step
406).
[0052] The random sequence [locat(K) .epsilon.{0,1},
1.ltoreq.k.ltoreq.S(LL.sub.n)] is set to have a probability defined
in Eq. 2. The user information S5 is embedded to a position
corresponding to "1" of the random sequence.
P(1)=ui.sub.--len/S(LL.sub.n) P(0)=1-ui.sub.--len/S(LL.sub.n) Eq.
2
[0053] Herein, ui_len and S(LL.sub.n) respectively represent the
size of LL.sub.n and the user information S5.
[0054] Provided in the following description are three experimental
results for the blind fingerprinting technique in accordance with
the present invention.
Experiment 1
[0055] 16-byte (128-bit) information is embedded to Barbara and
Lena's black-and-white picture having a size of 512.times.512 and
the embedded information is extracted after a JPEG compression
attack has been conducted thereto.
[0056] Conditions for the experiment 1 are as follows. [0057] User
information S5: ETRI WaterMarks! 16 bytes [0058] Image quality
(PSNR) after the embedding of the user information: 44.05 dB
(finger_Barb)
[0059] Table 1 shows the result of extracting the embedded
information after the JPEC compression attack is conducted at 46.45
dB (finger_Lena). TABLE-US-00001 TABLE 1 Image attack Objects
finger_Barb finger_Lena JPEG QF 10% U >
.quadrature..quadrature..quadrature.;.quadrature. MSeq
.quadrature..quadrature..quadrature.u.quadrature. JPEG QF 20%
dRTGeMrE(13)iY.quadrature. rB.quadrature.!tm O.quadrature. +
C.quadrature. JPEG QF 30% ]DRli.quadrature.terMk! .quadrature.Rl
Vat .quadrature..quadrature.r.quadrature. JPEG QF 40% ETRI
W!termarks% .quadrature.RI GAtermarks! JPEG QF 50% ETRI Watermarks!
ETRI Watermarks! JPEG QF 60% ETRI Watermarks! ETRI Watermarks! JPEG
QF 70% ETRI Watermarks! ETRI Watermarks! JPEG QF 80% ETRI
Watermarks! ETRI Watermarks! JPEG QF 90% ETRI Watermarks! ETRI
Watermarks!
Experiment 2
[0060] Different sets of user information are respectively embedded
to the black-and-white picture of 512.times.512 and an averaging
attack is conducted thereto. The result is shown in Table 2.
TABLE-US-00002 TABLE 2 Image quality Key values for after the
determining an Embedded User embedding of UI Result embedding
position Information (UI) (PSNR) Image 3000 joo sanghyun1632 46.14
dB img1 3001 kim jinho8606578 46.00 dB img2 3002 jang howook6694
45.55 dB img3 3003 moon kyungae5340 46.73 dB img4 3004 suh
youngho6841 46.45 dB img5
Experiment 3
[0061] A conspiracy trace is conducted based on correlativity with
other images for the averaging attack. The results are provided in
Tables 3 and 4. TABLE-US-00003 TABLE 3 avg1 = (img1 + img2)/2
decision img1 0.7938 Involved in conspiracy trace img2 0.7584
Involved in conspiracy trace img3 0.0417 img4 -0.0161 img5
-0.0236
[0062] TABLE-US-00004 TABLE 4 Avg2 = (img1 + img2 + img3 + img4 +
img5)/5 decision img1 0.4298 Involved in conspiracy trace img2
0.3665 Involved in conspiracy trace img3 -0.0068 img4 -0.0208 img5
0.4465 Involved in conspiracy trace
[0063] As described above, purchaser information is embedded to
digital contents sold through electronic commercial activities by
employing a non-blind fingerprinting and a blind fingerprinting
technique and is extracted depending on allowance or disallowance
of the use of an original image. Therefore, illegitimate copying
and distribution of the digital contents can be prevented, so that
property of the digital contents is effectively protected and safe
and legitimate distribution thereof is secured. Further, since the
system and method defined in the present invention are compatible
with existing encryption systems or control systems using a
specific browser and the system is designed to embed information,
regardless of whether the information is the user information or
any other kind of information related to a use control, to the
digital contents in a predetermined input amount, it is possible to
identify the owner of the contents and clarify where the
responsibility lies even though an encryption of the contents is
broken and the contents are illegally distributed. Accordingly, as
this technology is known to the public more and more, legitimate
distribution of the digital contents can be encouraged.
Furthermore, the present technology can be applied, in addition to
a stop image, to an audio/video system needing a real-time based
embedding and detection. In particular, if the present invention is
applied to a video system involving a large data amount, a greater
amount of data can be embedded and, further, a meta data for
managing the great amount of data need not be generated.
[0064] While the invention has been shown and described with
respect to the preferred embodiments, it will be understood by
those skilled in the art that various changes and modifications may
be made without departing from the spirit and scope of the
invention as defined in the following claims.
* * * * *