WO2008060115A1 - Procédé de détection de filigrane au moyen d'un sous-bloc et appareil correspondant - Google Patents

Procédé de détection de filigrane au moyen d'un sous-bloc et appareil correspondant Download PDF

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Publication number
WO2008060115A1
WO2008060115A1 PCT/KR2007/005767 KR2007005767W WO2008060115A1 WO 2008060115 A1 WO2008060115 A1 WO 2008060115A1 KR 2007005767 W KR2007005767 W KR 2007005767W WO 2008060115 A1 WO2008060115 A1 WO 2008060115A1
Authority
WO
WIPO (PCT)
Prior art keywords
sub
watermark
wnr
correlation
block
Prior art date
Application number
PCT/KR2007/005767
Other languages
English (en)
Inventor
Hyuk Choi
Hyun Wook Kim
Hae Kyung Jung
Tae Jeong Kim
Original Assignee
Hyuk Choi
Hyun Wook Kim
Hae Kyung Jung
Tae Jeong Kim
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hyuk Choi, Hyun Wook Kim, Hae Kyung Jung, Tae Jeong Kim filed Critical Hyuk Choi
Publication of WO2008060115A1 publication Critical patent/WO2008060115A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T1/00—General purpose image data processing
    • G06T1/0021—Image watermarking
    • G06T1/005—Robust watermarking, e.g. average attack or collusion attack resistant
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F15/00—Digital computers in general; Data processing equipment in general
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32—Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N1/32101—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N1/32144—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/32—Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
    • H04N1/32101—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
    • H04N1/32144—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
    • H04N1/32352—Controlling detectability or arrangements to facilitate detection or retrieval of the embedded information, e.g. using markers
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2201/00—General purpose image data processing
    • G06T2201/005—Image watermarking
    • G06T2201/0051—Embedding of the watermark in the spatial domain
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2201/00—General purpose image data processing
    • G06T2201/005—Image watermarking
    • G06T2201/0061—Embedding of the watermark in each block of the image, e.g. segmented watermarking
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2201/00—General purpose image data processing
    • G06T2201/005—Image watermarking
    • G06T2201/0065—Extraction of an embedded watermark; Reliable detection
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2201/00—General purpose image data processing
    • G06T2201/005—Image watermarking
    • G06T2201/0083—Image watermarking whereby only watermarked image required at decoder, e.g. source-based, blind, oblivious

Definitions

  • the present invention relates to a watermark, and more particularly, to a method and an apparatus for detecting a watermark using a sub-block.
  • the watermarking technique is designed to protect intellectual property with respect to contents by inserting copyright information, which is unrecognizable for people, into the copyrighted digital content of the copyright holder, when intellectual property right is legally disputed.
  • Watermark systems are classified into a type of a watermark system in which the watermark can be detected by using an original and a type of a watermark system in which the watermark can be detected without an original. The latter is referred to as a blind watermark system.
  • the watermark is added to the original signal or multiplied by the original signal. It is important to know how to find the inserted watermark more than to insert the watermark.
  • the present invention provides a method and an apparatus for detecting a watermark using a sub-block for optimizing correlation-detection performance.
  • a method of detecting a watermark using sub-blocks comprising: selecting a sub-block in which the watermark-to-noise ratio (WNR) is higher than a predetermined value; and correlation-detecting the sub-block, when the sub-block in which the WNR is higher than the predetermined value is selected.
  • WNR watermark-to-noise ratio
  • the selecting of the sub-block in which the WNR is higher then a predetermined value may comprises: dividing a block into a plurality of sub-blocks; calculating a WNR for each sub-block; and aligning WNRs in descending order and selecting a sub-block in which a WNR is equal to or greater than a predetermined value in which a variance of a degree of correlation among cover or stego signal and the watermark is minimized.
  • correlation-detection may be performed by using only the sub-blocks in which WNRs are higher than the predetermined value obtained until the lowest variance is detected.
  • an apparatus for detecting a watermark using sub-blocks which detect the watermark from a system including an encoder for encoding a signal by inserting a watermark signal into the signal, the apparatus comprises a detector which detects the watermark signal by selecting a part having higher WNR among signals output from the encoder and correlation-detecting the part.
  • the apparatus may further comprise: a sub-block processing unit which divides a block into a plurality of sub-blocks; a sub- WNR calculation unit which calculates a WNR for each sub-block obtained by dividing the block in the sub-block processing unit; a sub-WNR alignment unit which aligns WNRs in descending order according to the result calculated by the sub-WNR calculation unit; a correlation-detection entry selection unit which selects a part in which the WNR is equal to or greater than a predetermined value in which the degree z of correlation among the cover or stego signals and the watermark can be minimized, according to the alignment order obtained from the sub-WNR alignment unit; and a correlation-detection unit which detects watermark using sub-blocks selected by the correlation-detection entry selection unit.
  • the sub watermark-to-noise ratio alignment unit may align the WNRs in ascending order.
  • a correlation- detection entry may be selected from the back side of the sub-WNR alignment unit.
  • a watermark inserting device is used as in the past, and only a part having higher WNR according to characteristics of a cover signal (an original signal) is selected and watermark is detected using the selected part.
  • the watermark can be detected without errors and the detection performance is improved by selecting sub-blocks in which WNRs are high until the estimated variance of the degree of correlation is the minimum and performing correlation-detection using only the selected sub-blocks.
  • the watermark is robust with respect to various attacks such as compression, down sampling, DA/AD conversion, jittering, and recording by decreasing the variance between the cover signal and the watermark.
  • FIG. 1 illustrates an apparatus for detecting a watermark to which the present invention is applied
  • FIG. 2 illustrates a structure obtained by dividing a block into sub-blocks in an apparatus for detecting a watermark according to an embodiment of the present invention
  • FIG. 3 is a detailed block diagram illustrating a detector shown in FIG. 1;
  • FIG. 4 is a flowchart illustrating a method of detecting a watermark according to an embodiment of the present invention
  • FIG. 5 is a graph of a case where variance is large.
  • FIG. 6 is a graph of a case where variance is small.
  • FIG. 1 illustrates an apparatus for detecting a watermark to which the present invention is applied.
  • an original signal x[k] is not used.
  • noise n[k] is added due to an attack, watermark noise w[k] can be detected.
  • the correlation between w[k] and s[k] is obtained when the watermark is desired to be detected.
  • the watermark signal w[k] is noise which damages the original signal.
  • the watermark w[k] is the noise-like signal, it has to be under the following rules which are suitable to maintain signal quality. The rules will be described in the following.
  • the watermark signal w[k] to be concealed has to have a characteristic of a random number. Like the random number, irregularity of the watermark signal w[k] prevents attackers from estimating the watermark signal w[k]. Otherwise, the watermark signal w[k] can be easily estimated. The attackers attack the watermark signal w[k], thereby paralyzing the watermark signal w[k].
  • the random number has to be regenerated as it is.
  • the random number that satisfies the aforementioned characteristics is referred to as a pseudo-random number or PN sequence.
  • PN sequence When the pseudo-random number is used, the same pseudo-random number as the pseudo-random number used by an encoder can be regenerated by the detector, and the watermark can be reconstructed with the pseudo-random number.
  • ⁇ ,> indicates an inner product (scalar product).
  • N is a length of a signal x
  • P is a mean power of the signal x
  • E[c] is a mean value of the random number c
  • var[c] is a variance of the random number c.
  • the watermark is inserted by generating a stego signal s by adding a watermark aw to the cover signal x according to Math Figure 3.
  • the stego signal indicates a source obtained by inserting the watermark into the cover signal.
  • H is the abbreviation of hypothesis.
  • H indicates an index for representing a case.
  • H indicates a case where there is no watermark in the original signal.
  • H indicates a case where a watermark is inserted into the original signal.
  • FIG. 2 illustrates a structure obtained by dividing a block into sub-blocks in an apparatus for detecting a watermark according to an embodiment of the present invention. As shown in FIG. 2, blocks B of any data are divided into sub-blocks.
  • FIG. 3 is a detailed block diagram illustrating a detector shown in FIG. 1.
  • a watermark detector 200 is designed to detect a watermark signal by selecting a part of a signal output from the encoder 100 shown in FIG. 1, in which a watermark-to-noise ratio (hereinafter, abbreviated to WNR ) is high and correlation-detecting the part of the signal.
  • WNR watermark-to-noise ratio
  • the watermark detector 200 includes a sub-block processing unit 210, a sub- WNR calculation unit 220, a sub- WNR alignment unit 230, a correlation-detection entry selection unit 240, and a correlation-detection unit 250.
  • the sub-block processing unit 210 serves to divide blocks into a plurality of sub- blocks.
  • the sub- WNR calculation unit 220 serves to calculate a WNR for each sub- block obtained by dividing the blocks in the sub-block processing unit.
  • the sub-WNR alignment unit 230 serves to align WNRs in descending order, according to the result calculated by the sub-WNR calculation unit 220.
  • the correlation-detection entry selection unit 240 serves to select a part in which the WNR is equal to or greater than a predetermined value in which the degree z of correlation among the cover and stego signals and the watermark can be minimized, according to the alignment order obtained from the sub-WNR alignment unit 230.
  • the correlation-detection unit 250 serves to detect the watermark by correlation- detecting the sub-blocks selected by the correlation-detection entry selection unit 240.
  • the part in which WNR is high can be correlation-detected by correlation-detecting the back side of the sub-WNR alignment unit 230.
  • FIG. 4 is a flowchart illustrating a method of detecting a watermark according to an embodiment of the present invention.
  • a block of a watermark and a stego signal is divided into sub-blocks (operation SlO).
  • Sub-WNRs are calculated for the sub-blocks obtained by dividing the blocks of the watermark and the stego signal in operation SlO (operation S 12).
  • the sub- WNRs calculated in operation S 12 are aligned in descending order (operation S 14). That is, the sub-WNRs are aligned in ascending order of the WNRs.
  • the WNR is large, the variance is small.
  • Variance of the watermark detector is estimated by adding sub-blocks in the order of alignment.
  • N k indicates length of selected k number of sub-blocks.
  • FIG. 5 is a graph of a case where a variance is large. Referring to FIG. 5, since two histograms have wide widths, the two histograms overlap with each other.
  • FIG. 6 is a graph of a case where a variance is small.
  • the two histograms do not overlap with each other. That is, when the variance is large, the histograms have wide widths as shown in FIG. 5. When the variance is small, the histograms have narrow widths as shown in FIG. 6.
  • the watermark can be detected without errors and the detection performance is improved by selecting sub- blocks in which WNRs are high until the estimated variance of the degree of correlation is the minimum and performing correlation-detection using only the selected sub-blocks.
  • the watermark is robust with respect to various attacks such as compression, down sampling, DA/AD conversion, jittering, and recording by decreasing the variance between the cover signal and the watermark.

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Computer Hardware Design (AREA)
  • General Engineering & Computer Science (AREA)
  • Editing Of Facsimile Originals (AREA)
  • Image Processing (AREA)

Abstract

La présente invention concerne un procédé et un appareil de détection de filigrane au moyen d'un sous-bloc. Selon le procédé de l'invention, il est possible d'améliorer les performances de détection de filigrane par sélection de sous-blocs ayant un rapport filigrane-bruit (watermark-to-noise ratio / WNR) supérieur, puis exécution d'une corrélation-détection avec les sous-blocs sélectionnés. En outre, le procédé est résistant vis-à-vis des offensives existantes.
PCT/KR2007/005767 2006-11-17 2007-11-16 Procédé de détection de filigrane au moyen d'un sous-bloc et appareil correspondant WO2008060115A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020060114013A KR100862101B1 (ko) 2006-11-17 2006-11-17 서브 블록을 이용한 워터마크 검출 방법 및 그 장치
KR10-2006-0114013 2006-11-17

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WO2008060115A1 true WO2008060115A1 (fr) 2008-05-22

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Cited By (2)

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Publication number Priority date Publication date Assignee Title
CN104182927A (zh) * 2014-09-12 2014-12-03 北京国双科技有限公司 图片水印添加方法及装置
CN105761199A (zh) * 2016-03-25 2016-07-13 鲁东大学 一种基于组合域的鲁棒彩色图像水印方法

Families Citing this family (2)

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Publication number Priority date Publication date Assignee Title
KR101051002B1 (ko) * 2010-02-09 2011-07-26 (주)인포마크 서브스페이스 기반의 비대칭 워터마킹 시스템
KR101271197B1 (ko) * 2011-10-20 2013-06-07 한국과학기술원 가로축 노이즈 평균이동을 이용한 워터마킹 시스템

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WO1999060792A1 (fr) * 1998-05-20 1999-11-25 Macrovision Corporation Procede et appareil de traitement de bloc selectif
US6707928B2 (en) * 2000-11-29 2004-03-16 Intel Corporation Method for block-based digital image watermarking
US7013021B2 (en) * 1999-03-19 2006-03-14 Digimarc Corporation Watermark detection utilizing regions with higher probability of success

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US5915027A (en) * 1996-11-05 1999-06-22 Nec Research Institute Digital watermarking
KR100560429B1 (ko) * 2003-12-17 2006-03-13 한국전자통신연구원 비선형 양자화를 이용한 워터마킹 장치 및 그 방법

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WO1999060792A1 (fr) * 1998-05-20 1999-11-25 Macrovision Corporation Procede et appareil de traitement de bloc selectif
US7013021B2 (en) * 1999-03-19 2006-03-14 Digimarc Corporation Watermark detection utilizing regions with higher probability of success
US6707928B2 (en) * 2000-11-29 2004-03-16 Intel Corporation Method for block-based digital image watermarking

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104182927A (zh) * 2014-09-12 2014-12-03 北京国双科技有限公司 图片水印添加方法及装置
CN104182927B (zh) * 2014-09-12 2017-12-19 北京国双科技有限公司 图片水印添加方法及装置
CN105761199A (zh) * 2016-03-25 2016-07-13 鲁东大学 一种基于组合域的鲁棒彩色图像水印方法
CN105761199B (zh) * 2016-03-25 2018-10-12 鲁东大学 一种基于组合域的鲁棒彩色图像水印方法

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Publication number Publication date
KR20080044680A (ko) 2008-05-21
KR100862101B1 (ko) 2008-10-09

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