DWT-BAT Based Medical Image Watermarking For Telemedicine Applications

Transcription

1 DWT-BAT Based Medcal Image Watermarkng For Telemedcne Applcatons 1 N.Venkatram, 2 L.S.S.Reddy, 3 P.V.V.Kshore, 1 K.L.Unversty, Dept of E.C.M, KL Unversty, Vaddeswaram, Green Felds, GUNTUR, AP, INDIA 2 K.L.Unversty, Dept of C.S.E, KL Unversty, Vaddeswaram, Green Felds, GUNTUR, AP, INDIA 3 K.L.Unversty, Dept of E.C.E, KL Unversty, Vaddeswaram, Green Felds, GUNTUR, AP, INDIA ABSTRACT Medcal mages communcate mperatve nformaton to the doctors about a patent s health stuaton. Internet broadcasts these medcal mages to naccessble stes of the globe whch are nspected by specalst doctors. But data transmssons through unsecured web nvoke valdaton problems for any mage data. Medcal mages that are transmtted through the nternet must be watermarked wth patent pctures for substantaton by the doctors to ascertan the medcal mage. Medcal mages contan very susceptble nformaton connected to a patent s health. Watermarkng medcal mages necesstate attentve adjustments to protect the nformaton n the medcal mages wth patent mage watermarks. The medcal mages are used as an envelope mage n the watermarkng process whch s vsble on the network. These envelope medcal mages are watermarked wth patent mages n wavelet doman there by usng the BAT algorthm form optmzng the embeddng process for peak sgnal to nose rato(psnr) and normalzed cross correlaton coeffcent (ncc) values. The medcal mage envelope and letter nsde envelope.e. watermark mage are transformed nto wavelet doman and are mxed usng scalng factor alpha whch s termed as embeddng strength. BAT algorthm s an optmzaton algorthm specalzed n optmzng the values of peak-sgnal-to-nose rato for a partcular value of alpha, the embeddng watermark strength. Fnally these watermarked medcal mages are put on the network along wth the secret key that wll be used for extracton. At the recevng the embedded watermark s extracted usng 2DWT usng the embeddng strength value usng BAT algorthm. The robustness of the proposed watermarkng technques s tested wth varous attacks on the watermarked medcal mages. Peak-Sgnal-to-Nose ratos and Normalzed cross correlaton coeffcents are computed to accesses the qualty of the watermarked medcal mages and extracted patent mages. The results are produced for three types of medcal mages wth one patent mage watermarks usng sngle key by usng four wavelets (haar, db, symlets, bor) at four dfferent levels (1&2). Keywords: Medcal Image Watermarkng, Dscrete Wavelet Transform (DWT), Optmzaton algorthms, BAT algorthm, MRI, CT and Ultrasound Images, psnr and ncc. 1. INTRODUCTION Watermarkng dgtal multmeda Cox I J, Kllan et al (1997), M.D. Swanson et al (1998), Podlchuk et al (1998), Hartung et al(1999), contents has grown rapdly n the recent past wth the advances n nternet technology. Ths watermarkng functonalty s to hde nformaton, protect dgtal copyrghts and for content dentfcaton of multmeda contents exchanged over the nternet. Internet data travels through unprotected routng swtches all over the world. Hence watermarkng comes to the rescue for protectng multmeda data that s transmtted through these unsecured servers. Medcal mage watermarkng Haley.D et al(1999), Güler et al(2002), Haley et al (2002), Smth et al(2005) functons sgnfcantly n supportng a patent by conveyng hs nfrmty usng medcal mages through unsecured networks such as the nternet to expert doctors around the world. Ths practce helps to expand the possblty of dstantly statoned patents where no expert medcal doctor s accessble to ncrease ther probablty of endurance.

2 Traffckng medcal mages through unsecure nternet s prone to unwelcomed modfcaton to the senstve contents of the medcal mages. Medcal mages contan vulnerable nformaton whch s valuable related to the health of the patent. Medcal practtoner has to take supreme care to check that the mages are not meddled wth, before analysng the medcal mages downloaded from the unsecured nternet. For ths reason, authentcaton of medcal mages such as Ultrasound scans, MRI scans, x-ray and Computer Tomography (CT) scans has to be watermarked. The host medcal mage can be watermarked wth patent nformaton before transmttng on the nternet. At the physcan s end t has to de watermarked before proceedng for dagnostcs. Medcal cover mages are watermarked wth patent mage as watermark whch forms an nvsble detecton code. A medcal mage watermarkng s a perfectly hdden watermarkng pardgrams as proposed by Anand et al (1998). The applcaton of medcal mage watermarkng s towards telemedcne. In recent years medcal mage watermarkng s prmarly used to hde patent nformaton such as patent s name, age, gender whch can unquely dentfy a patent by Zan et al (2006). Ths patent related watermark nformaton s extracted to determne the authentcty of the medcal mages. As the extracted watermark from the medcal mage matches the patent data n the doctor s offce, t s proved that these medcal mages belong to a partcular patent n Navas(2007). There s a growng demand for applcatons related to watermarkng due to the ever ncreasng storage and sharng of dgtal meda contents around the world on the nternet. Watermarkng has nvaded every multmeda transmsson on the nternet such as text documents (Jall et al (2009)), mages (E.T. Ln et al (1999)) and even audo (Boney et al (1996)) and vdeo data watermarkng (Wolfgang et al (1999)). Varous dgtal mage watermarkng schemes are proposed and mplemented successfully by researchers around the world n an mage s spatal doman (Nkolads et al(1998)), transform doman (P.V.V.Kshore et al(2014)) along wth encrypton technques whch as robust (P.V.V.Kshore et al(2014)), sem-fragle (E.T. Ln et al (1999)) and some are fragle watermarkng schemes. The growng need for medcal mage watermarkng schemes s due to the usage of nternet to transfer medcal mages among expert doctors for advces and case studes. Medcal mages can and are savng human lves around the world. But wth sharng comes the fear of hackers. Hackers attack these medcal mages modfyng ther detals makng the medcal mage data msleadng to a doctor. Ths pont can be better proved by lookng at the orgnal and modfed medcal mages as shown n fgure 1 and fgure 2. Fgure 1(a). Orgnal MRI Bran mage Transmtted to the Doctor through nternet Fgure 1(b). Hacked MRI Bran mage Transmtted to the Doctor through nternet Fgure 2(a). Orgnal CT Bran mage Transmtted to the Doctor through nternet 2 Fgure 2(b). Hacked CT Bran mage Transmtted to the Doctor through nternet

3 Fgures 1(a) s the orgnal MRI mage of a patent. When a doctor at a remote locaton wants a second opnon about the dsease, he transmts t to another expert through nternet. Fgure 1(b) shows the modfed medcal mage by the hackers. Ths knd of modfcatons can sometmes cost a human lfe. Here there s a need to prevent medcal data from hackers and prove the authentcty of the medcal mages at the recevng doctor s end. Fgure 2 shows the orgnal and attacked CT bran mage. Coatreux et al (2000) enlghtened that dgtal watermarks should be consdered as a securty tool n order to protect medcal records. Gakoumak et al (2003) proposed a wavelet transform-based watermarkng, whch fulflls the strct requrements concernng the acceptable alteratons of medcal mages. The proposed scheme embeds numerous watermarks helpng dverse functonalty such as authentcaton contanng doctor s dgtal sgnature as a robust watermark, patent s personal and examnaton related data and a fragle watermark for data ntegrty control. Thus, they state that the watermarkng tool offers alternatves for dfferent ssues assocated wth medcal data management and dstrbuton. Ths research paper proposes to fnd whch wavelets are better for watermarkng medcal mages and up to what level of decomposton wll result n perfect watermarked mage. Irany et al (2011) proposes a hgh capacty reversble multple watermarkng scheme for medcal mages based on nteger-to-nteger wavelet transform and hstogram shftng. The novelty of the proposed scheme s that t uses a scalable locaton map and ncorporates effcent stoppng condtons on both wavelet levels and dfferent frequency subbands of each level to acheve hgh capacty payload embeddng, hgh perceptual qualty, and multple watermarkng capabltes. Results show that the proposed method attans hgh perceptual qualty n hgh capacty rates for the medcal mages. Lavanya et al (2012)proposed non regon of ntrest(nroi) based medcal mage watermarkng schemes[22] where the patent detals are embedded n non-roi regon of an mage. The encrypted mage s dvded nto non overlappng tles to dentfy regon of nterest and non-regon of nterest. In examnaton ste examner embeds patent detals n non-roi of encrypted mage usng a data-hdng key. Wth an encrypted mage contanng patent detals, a recever may frst defle and decrypt t usng the encrypton key, and the decrypted verson s smlar to the orgnal mage. Wakatan et al (2002), proposes a dgtal watermarkng technque by shunnng the deformaton of the mage data n ROI by embeddng watermark nto areas other than the ROI. Watermark mage s compressed by a progressve codng algorthm whch s used as the sgnature nformaton. The proposed method can detect the sgnature mage wth moderate qualty from a clpped mage ncludng the ROI. Furthermore, by dvdng the contour of the ROI nto several regons and embeddng the sgnature nformaton n the regons respectvely, the sgnature mage wth moderate qualty can be acqured from a clpped mage ncludng only part of the ROI. Ths research proposes to use wavelet transform and BAT algorthm proposed by X.-S. Yang (2010) and Xn-She Yang (2012) for medcal mage watermarkng. The medcal mage s transformed nto wavelet doman usng a 2D DWT. The type of mother wavelet and level of scalng are two parameters that are of nterest to look for whle applyng the algorthm. Watermark n ths case s a patent mage. Ths patent mage s embedded nto the medcal cover mage n transform doman. The extracton process s a nverse algorthm to embeddng process. From the watermark embeddng and extracton process two performance parameters are computed n the form of peak-sgnal-to-nose rato (psnr) and normalzed cross correlaton (ncc). Ths procedure of watermarkng gves unpredctable outcomes for medcal mages as cover mages wth out of bounds psnr and ncc values. These unpredctable results of watermarkng algorthm can be controlled usng optmzaton algorthms such genetc algorthm (GA), partcle swarm optmzaton (PSO) and ant colony optmzaton (ANO). Ths research uses BAT algorthm for optmzng the psnr and ncc values durng watermark embeddng and extracton process. The results of smulaton show a better performance of BAT algorthm over GA and non optmzaton watermarkng process for medcal mages wth patent mage as watermark[28]. 3

4 The rest of the paper s organzed as follows. Secton 2 gves a bref ntroducton of dscrete wavelet transform and BAT algorthm (Altrngham (1996)). Secton 3 deals wth the process of watermarkng. Secton 4 gves medcal mage dewatermarkng algorthm. Results and dscusson n secton 5 present nsghts nto the use of multresoluton wavelet transform wth BAT for medcal mage watermarkng. Fnally conclusons are made on the medcal mage watermarkng procedures n secton WAVELET THEORY AND BAT ALGORITHM Ths research proposes the use of two most popular technques used n data encrypton and mage processng n computer communcatons for copyrght protecton. The watermarkng of the encrypted patent mage watermark nto a medcal mage s accomplshed usng 2D dscrete wavelet transform. The amount of watermark requred for producng a nformaton preservng watermark s done usng optmzng the values of psnr and ncc wth the help of BAT algorthm. Ths secton provdes the bascs of DWT and BAT algorthm used for medcal mage watermarkng. 2.1 Dscrete Wavelet Transform M Wavelet transform s appled to decompose a medcal mage I ( x, y) nto varous levels of abstracton A H V D,,, and can be reconstructed perfectly wth fewer number of wavelet coeffcents wthout compromsng on vsual qualty n P.V.V.Kshore et al (2011, 2012, 2012). The structure of Wavelet transform provdes an multlevel decomposton on mages, wth each level correspondng to a lesser resoluton compared to the prevous level as shown n fgure 3. Ths mult resoluton analyss of 2D DWT permts to decompose an mage nto approxmate and detals coeffcents. The 2D dscrete wavelet transform dvdes the mage nto low frequency (L) and hgh frequency components (H) at level1 usng 4 decomposton flters{ll_d, LH_D, HL_D, HH_D}. M The 2D medcal mage I ( x, y) passes through low pass flter and a downsampler of level 2 to produce approxmate mage at level-1 wavelet decomposton. Smlarly 2D medcal mage I ( x, y) s appled to a hgh pass flter and downsampler to create detaled mage at level-1 wavelet decomposton. Further n level2 decomposton the low frequency nformaton s agan dvded nto four LL, LH,HL and HH coeffcents. The hgh frequency detaled components n level1 are ntact. The second level decomposton also uses same set of decomposton flters as level-1. The wavelet decomposton process s shown n the fgure 3. M Fgure 3: Wavelet Decomposton of an Ultrasound Medcal based on 2D Flter Dscrete Wavelet 4 Transform

5 The noton L 2 (R 2 M ), where R s a set of real numbers, denote the fnte energy functon I ( x, y ) n R 2 ; and x,y n R. In two dmenson wavelet transform, a 2D scalng functon ( xy, ), and three two dmensonal wavelets, H ( xy, ), V ( xy, ) and D ( xy, ) are produced as shown n fgure 3. The above functons represent gray level varatons along dfferent drectons such as horzontal varatons, vertcal varatons and dagonal varatons. The DWT of I ( x, y ) of sze M N s M1N1 1 M 0 0 MN m0 n0 W ( j, m, n) I ( x, y) ( j, m, n) (1) Where j, m, n, M, N are ntegers, = {H, V, D}, j0 s an arbtrary startng scale and the coeffcents W defne an approxmaton of f at scale j 0. M1N1 1 M ( 0,, ) (, ) j, m, n MN x0 y0 W j m n I x y (2) The coeffcents n the above equaton add horzontal, vertcal and dagonal detals as shown n fgure.3.8 for scales j j0. The j, m, n and j, m, n denote scaled and translated bass functons as shown below, j, m, n j /2 j ( x, y) 2 (2 x m,2 n 1) j /2 j j, m, n M ( x, y) 2 (2 x m,2 n 1) Gven W and W, I ( x, y ) s obtaned va nverse DWT as: M1N1 1 W j0 j IM W j W W 0 j MN m0 n0 j j0 Eq.4 produces a watermarked medcal mage n spatal doman. 2.2 BAT Algorthm (4) BAT algorthm s a heurstc search and optmzaton algorthm based on echolocaton behavor of bats was proposed by Xn-She Yang(2010). Bats use sonar type of processng called, echolocaton, to locate prey, to avod obstructon and navgate through the dark nghts. Bats lsten to the echo s that are receved from the surroundng objects by transmttng a very loud sound pulse. Dfferent speces of bats use sound pulses wth dfferent propertes such as short frequency modulated sound pulses or constant frequency sound pulses. Ths echolocaton behavor of bats s devsed to optmze a gven objectve functon as proposed by Xn-She Yang(2010) s called BAT Algorthm(BA). The startng pont n BAT based optmzaton algorthm s to defne a objectve functon f x. Intalze a few parameters such as bat populaton x ( 1 to n) and ntal veloctes of bats v. Intalze pulse max frequency f at x. Pulse frequency can vary n the range f 0, f 1 to n. For a partcular optmzaton functon the soluton space can be adjusted by selectng frequency range close to sphere of nterest. Fnally ntalze pulse rate and loudness L. By selectng teratons tr to a specfc count, new solutons are generated by adjustng the frequences. Ths means the bats try to reach ther target M (3) 5

6 locaton by adjustng ther frequences and computng ther veloctes and locatons at each new frequency. Ths computaton can be mathematcally modeled as mn max mn f f f f (5) Where 0,1 s a unformly dstrbuted random vector. * tr tr1 tr v v x x f (6) * Where vtr 1 s the ntal velocty of the bat populaton. x s the current global best soluton,.e. locaton of the target whch s located after comparng all the solutons among all the n bats. The fnal or next best locaton of the target can be updated usng the followng mathematcal model xtr xtr 1 vtr (7) From eqn(7) t can be seen that the locaton or soluton space s updated wth the bat updated velocty n each teraton v tr. vtr n turn s derved from bat frequences or wavelengths as vtr ftr or f tr. Intally bat frequences are randomly allocated between [ f, f ], whch can be chosen based on the objectve functon that s beng mnmzed. The above process provdes a soluton space contanng global best postons of the n bats target. A local best soluton can be generated locally for each bat usng random walk n o tr x x L (8) n x s the new locaton or soluton space that s produced from mn max o x, the old global soluton space usng a loudness updaton factor wth a random constant 1,1. Further updaton of loudness are done between teratons. L and pulse rate n L ntal loudness can be set as 1 and the fnal loudness that s to be fn reached s set as L 0 ndcatng that the bat has fnally reached ts target where t stops temporarly ts search process. The new loudness factor can be mathematcally modeled as tr tr1 L L (9) Where s a constant. The pulse rate s updated as ( ) 0 1 tr tr e (10) Where s a constant. For our expermentaton both the defned constants are gven values rangng from 0 to 0.7 based on varous medcal cover mages used for watermarkng. A seres of experments are to be conducted to fx the values of loudness Ltr and pulse rate tr. For watermarkng smulatons usng medcal mages as cover mages the value of loudness vares L 0.5,1.5 and pulse rate 0.2, WATERMARK EMBEDDEDING tr. Watermarkng s wavelet doman s not new to researchers. Our prevous work N.Venkatram et al (2014), used dscrete wavelet transform to watermark medcal mages. Fgure 4 shows the watermarkng technque used by N.Venkatram et al Ths medcal mage watermarkng usng wavelet transform s modfed n ths research paper as shown n fgure 5. The modfcaton s proposed usng BAT algorthm to optmze the values of psnr and ncc to produce a good embeddng strength for the watermark. Our technque s very robust to attacks whch wll be demonstrated usng smulatons n secton 5. Medcal Images of standard resoluton are watermarked wth ther analogous patent mage as watermark of slghtly lower resoluton of usng the followng steps. S1. Carry out n th level 2D Dscrete Wavelet Transform (DWT) on the Medcal Image (Cover Image) (N.Venkatram et al (2014)) and decompose n to followng sub-bands (LL, LH, HL, HH). Where n s the tr 6

7 number of levels a wavelet s supposed to be decomposed. In our research we tred wth four dfferent levels.e. n=1, 2, 3 and 4. S2. The watermark s embedded usng the formula Sub e W(, j) W (, j) 2 (2 w ( k) 1) (11) Where W(, j) s watermarked medcal mage wth encrypted patent mage. W (, j) s n th level wavelet subbands of medcal mage. s the rato of standard devaton of wavelet coeffcent block and the maxmum standard devaton of all the coeffcent blocks. s the fxed embeddng watermark strength whch wll be found usng BAT algorthm n ths paper. w ( k) s the encrypted patent mage at k th poston. S3. Assemble all the modfed sub-bands and apply nverse 2D Wavelet Transform (IDWT) and s formulated as WM ( n) I W (12) 1 Where n represents 4 sub-bands for n=1, LL, LH, HL, HH. s the watermarked medcal mage. The WM watermarked medcal mage I s obtaned whch contans patent mage as watermark. S4. Compute embedded psnr and ncc values usng the watermarked medcal mage and orgnal medcal mage from equatons 14 and 15 n secton 5. S5. Intalze BAT algorthm parameters as dscussed n secton 2.2. The value of s estmated usng BAT algorthm. Psnr and ncc are used as objectve functons for optmzaton. Psnr should have a mnmum value and ncc should have a maxmum value less than 1. Proposed watermarkng s shown n fgure 5. e Sub Fgure 4. Medcal Image Watermarkng n Wavelet Doman 7

8 BAT algorthm returns value of by optmzng the values of psnr and ncc for embeddng the patent mage watermark nto the medcal cover mage. The value of s updated n every teraton tll optmum values of psnr and ncc are not reached. The only constrant n usng an optmzaton technque for medcal mage watermarkng s the tme for smulaton, whch n ths case s acheved wth teratons ranged tr 15,36. as 4. WATERMARK EXTRACTION PROCESS WM The watermarked medcal mage I s sent dstantly through unsecured nternet servers to expert medcal doctors from remote parts of the world. At the doctor s place the system decouples the attacked watermarked medcal mage form the watermark for authentcaton. The followng extracton process s ncorporated at the doctor s sde to extract the encrypted watermark patent mage and decrypt the patent watermark mage. S1. The possbly attacked watermark medcal mage s treated wth 2D dscrete wavelet transform (DWT) and decomposed to n th level wth n sub-bands LL, LH, HL and HH. S2. Medcal mage s decoupled from the patent watermark mage usng the nverse expresson RM M ep 2( W (, j) W (, j)) I ( x, y) (2 ) 1 RM Where W (, j) s transformed the receved watermarked medcal mage at th and j th locaton. M W (, j) s the subbands of orgnal cover mage that s receved wth the transmtted watermarked mage. ep I ( x, y) s the recovered watermark patent mage. S3. Extracted watermark s a patent mage whch agan s accomplshed usng a precse value of. Ths value s estmated usng BAT algorthm by computng values from extracted psnr and ncc objectve functons. An optmum value of s obtaned for extracton of watermarked medcal mages. Fnally authentcaton of the medcal mage s dentfed by extracted patent mage. 5. RESULTS AND DISCUSSION The proposed watermarkng method s put nto operaton on MATLAB software wth three dfferent types of medcal mages whch are consdered as cover mages. MRI, CT and Ultrasound medcal (US) mages are used as cover mages of standard resoluton Watermark s a patent mage of resoluton Snce medcal mages are gray scale mages, t s ntended to consder grayscale patent mage as watermark. The dynamc standard devaton rato factor σ s used for watermarkng n our experments whch s computed from wavelet coeffcents. The other scalng factor s estmated usng BAT algorthm. The estmaton of optmum embeddng strength, for mnmum value of psnr and maxmum value of ncc s used to embedded the patent watermark n the medcal cover mage. The performance of the proposed medcal mage watermarkng s judged by computng peak sgnal to nose rato (psnr) and normalzed cross correlaton coeffcent (ncc). These parameters wll decde the robustness of the watermarkng method usng DWT watermarkng process by most of the researchers. Watermarkng of medcal mages s relatvely susceptble process as the medcal mages contan nformaton related to lfe changng scenaros of human subject. Corrupton of the orgnal medcal mage by watermarkng process should be wthn the acceptable confnes of human percepton. The vsual (13) 8

9 senstvty of the watermarked and extracted mages s mathematcally represented by calculatng psnr and ncc. The values of psnr and ncc values are refned usng BAT algorthm to produce a watermarked medcal mage that exactly mmcs the orgnal medcal mage before watermarkng. 5.1 Embedded Peak Sgnal to Nose Rato (psnr) Embedded psnr [29] s the measure of peak error between orgnal mage and watermarked mage and s computed usng the followng expresson 2 M MN max(max( I ( x, y) psnr 10log (14) 10 2 M MI I ( x, y) W xn ym M Where N and M represent mage resoluton. I ( x, y) s the orgnal medcal mage and W s the watermarked medcal mage. psnr s the peak sgnal to nose rato n db whch range between 40db to 60 db generally for good watermarkng. 5.2 Extracted Normalzed Cross Correlaton Coeffcent (ncc) Normalzed cross correlaton [29] s mostly used by pattern recognton research for measurng smlarty between a query mage and the mages from the database. The cross correlaton s normalzed by subtractng the mean and dvdng by standard devaton. Embedded normalzed cross correlaton coeffcent gves the measure of closeness between watermarked mage and orgnal medcal mage. M ncc xn ym M M I ( x, y) W ( x, y) 2 2 M M I ( x, y) W ( x, y) xn ym xn ym (15) The values of normalzed cross correlaton coeffcents (ncc) range from 0 to 1. Larger values of ncc are preferred for better watermarkng. Fgure 6 shows a patent s skull CT along wth ts 2D dscrete wavelet transform. 2D DWT decomposes the medcal mage usng db2 mother wavelet to level-1 decomposton. All the medcal mages used n ths research are acqured from radology department of NRI medcal college and Hosptal at Guntur, Andhra Pradesh, INDIA. Fgure 6(a) shows orgnal bran CT mage of a patent. Fgure 6(b) shows a decomposed CT medcal mage usng db2 wavelet. 9 (a) (b)

10 (a) (b) Journal of Engneerng Technology CT bran medcal mage( ) s used as cover mage for watermarkng n fgure 7(a) and lena mage s used as patent mage(64 64) n fgure 7(b). DWT-BAT watermarkng procedure proposed n ths research embeds watermark patent mage nto bran CT cover mage to produce a watermarked medcal mage as shown n fgure 7(c). Fgure 7(d) shows the extracted watermark of patent mage. Vsually fgure 7 shows that the watermarked mage and extracted mage match powerfully as per human vsual system. Fgure 7: (a) Bran CT Cover Image (b) Watermark Patent Image (c) CT Watermarked Medcal Image (d) Extracted Watermark patent mage Fgure 7 shows the robustness of DWT-BAT algorthm. Smlar results are acqured usng MRI bran mage, fgures 8 and 9, and Ultrasound (US) Medcal mages, fgures 10 and 11 as cover mages. 10

11 Fgure 9: (a) MRI Bran Cover Image (b) Watermark Patent Image (c) MRI Watermarked Medcal Image (d) Extracted RSA Encrypted Watermark (e) Decrypted Watermark patent Image Wth KEY (a) (b) Fgure 10: Dscrete Wavelet Transform of Level -1 usng db2 mother wavelet (a) Orgnal pregnant ultrasound (US) Medcal Image (b) ts 2D DWT 11

12 From fgure 11(c) t can vsually be observed that the watermarkng process proposed n ths paper has actually removed nose from the ultrasound mage. At ths pont we want to hghlght the use of optmzaton technque such as BAT algorthm for watermarkng. Fgure 12 shows the comparson of DWT-BAT proposed n ths research to other watermarkng technques used by us [] for medcal mage watermarkng. Fgure 12.Vsual Comparson of (d) DWT-BAT wth three other medcal mage watermarkng methods used by us prevously (a) Only DWT (b) RSA-DWT (c) LWT-SVD Performance of the watermarkng methods s also formulated usng equatons 14 and 15 n Table-I for the embedded watermark and orgnal medcal mage for all three dfferent medcal mages. The values are computed for all our prevously accomplshed methods. The data analyss hghlghts the effectveness of the DWT-BAT watermarkng method for medcal mage watermarkng wth patent mage as a payload. Table-1: Embedded psnr and ncc for Medcal Cover Images for varous watermarkng methods 12

13 Watermarkng Method Cover Medcal Image PSNR (db) DWT RSA-DWT LWT-SVD DWT-BAT NCC PSNR (db) NCC PSNR (db) NCC PSNR (db) MRI CT Ultrasound(US) Performance plots usng embedded psnr and ncc are plotted from table-1 n the fgures 13 and 14 respectvely. From the graphs t can be confrmed that DWT-BAT outperforms the other watermarkng methods usng medcal mages of varous types. NCC Fgure 13. Comparson graph for watermarkng methods wth DWT-BAT usng embedded psnr values Fgure 14. Comparson plot for watermarkng Methods wth DWT-BAT usng ncc values The performance analyss for extracton of watermark and the qualty of medcal cover mage are very smlar to that of embeddng process for all the watermarkng methods. In the extracton process also there s a clear dstncton shown by DWT-BAT watermarkng algorthm whch outperformed all other methods. Computng normalzed cross correlaton coeffcent form equaton 15 for the extracted watermark patent mages reveals the performance of the RSA-DWT medcal Image watermarkng process. The values are put up n Table-2. The watermarked medcal mages are transmtted through unsecured networks and are most lkely to be attacked from varous unlawful hackers. Hence to test the robustness of the watermarkng method proposed n ths paper, varous attacks are smulated. The total number of attacks smulated for testng our DWT-BAT proposed watermarkng algorthm s 12. Generally the ncc coeffcent for better watermark s somethng above 0.75[16]. For remarkably excellent correlaton the value of ncc should be around or 1. A value of zero for ncc ndcates a complete uncorrelaton between the orgnal cover mage and the watermarked mage. Table-2 ncc values are computed for db2 wavelet at level-1 of watermarked mage. Table 2: Comparson of Extracted watermarks Cover Images DWT RSA-DWT LWT-SVD DWT-BAT Attacks MRI CT US MRI CT US MRI CT US MRI CT US Mean Flterng Medan Flterng Rotaton (45 ) Rotaton (135 ) Rotaton (225 ) Rotaton (315 ) Gaussan Nose

14 (0.001) Gaussan Nose (0.005) Gaussan Nose (0.01) Salt & Pepper Nose( ) Shear [x=1,y= ] Crop(10 0,100) The watermarked medcal mage s subjected to twelve attack categores such as a 3 3 wndow mean flterng, a 3 3 wndow medan flterng, 45, 90, 135 and 180 rotaton, Gaussan nose and salt & pepper nose of nose denstes 0.001,0.005,0.01 and 0.1, shear attack wth [x=1,y=0] and fnally crop wth crop area [100,100]. Table-2 shows the robustness of DWT-BAT under these attacks. Plottng the extracted ncc values of the patent mage watermark for varous technques wth three sets of medcal cover mages wll reveal the extraordnary qualty of watermarks produced by proposed DWT-BAT watermarkng algorthm. Fgure 15 plots ncc values of extracted patent mage watermarks for 4 watermarkng procedures aganst attacks wth MRI cover mages. Smlar plots are produced n fgures 16 and 17 for CT and US medcal cover mages. Fnally fgure 18 shows the dynamc range varatons n extracted watermark ncc values for three medcal cover mages n four dfferent watermarkng algorthms. Fgure 15:Plot showng Extracted ncc values for MRI Medcal cover mages aganst varous attacks for 4 watermarkng algorthms Fgure 16:Plot showng Extracted ncc values for CT Medcal cover mages aganst varous attacks for 4 watermarkng algorthms 14

15 Fgure 18. Box plot showng dynamc range of extracted watermark ncc values From the box plot of fgure 18, t s observable that the extracted ncc values for the proposed DWT- BAT watermarkng algorthm have produced a small dynamc range compared to our prevously smulated watermarkng algorthms under attacks for medcal mage watermarkng. Ths shows that the proposed DWT-BAT watermarkng for medcal mages can wthstand attacks and reproduce better qualty extracted watermarks. Vsual analyss of the attacked watermarked mages wth ther extracted medcal cover mages and watermark patent mages are shown n fgures for three types of medcal cover mages.e. MRI, CT and US respectvely. 15

16 Fgure 20. Extracted Patent mages from US Watermarked Images wth db2 after (a) 3 3 wndow mean attack,(b) medan attack,(c)-(f) rotaton attacks,(g)-(j) nose attack, and (k) shows shear attacks and (l) crop attacks Fgure 21. Attacked watermarked CT Images(a)Mean (b) Medan (c)gaussan Nose(.001) (d) Gaussan Nose(0.005)(e) Gaussan Nose(.01) (f) Salt & Pepper Nose(.001) (g) Rotaton (45 0 ) (h) Rotaton (135 0 ) () Rotaton (225 0 ) (j) Rotaton (315 0 ) (k) Shear attack(x-1,y=0) (l) Crop attack (100,100) 16

17 Fgure 23. Attacked watermarked CT Images(a)Mean (b) Medan (c)gaussan Nose(.001) (d) Gaussan Nose(0.005)(e) Gaussan Nose(.01) (f) Salt & Pepper Nose(.001) (g) Rotaton (45 0 ) (h) Rotaton (135 0 ) () Rotaton (225 0 ) (j) Rotaton (315 0 ) (k) Shear attack(x-1,y=0) (l) Crop attack (100,100) Fgure 24. Extracted Patent mages from US Watermarked Images wth db2 after (a) 3 3 wndow mean attack,(b) medan attack,(c)-(f) rotaton attacks,(g)-(j) nose attack, and (k) shows shear attacks and (l) crop attacks From fgures 19,21 and 23, t can be observed that the attacked watermarked medcal mages usng DWT-BAT algorthm produces remarkably good medcal mages wthout loss of nformaton related to patents health. The watermarked medcal mages after attacks are very close to orgnal medcal mages n both vsual qualty and quanttatvely usng psnr and ncc values from table-2. Smlarly extracted watermark patent mages from attacked watermarked medcal mages wth proposed DWT-BAT algorthm are of good qualty as shown n fgures 20, 22 and 24. Ths DWT-BAT watermarkng algorthm was tested for varous decomposton levels of dscrete wavelet transform and varous mother wavelets. The vsual qualty of watermarked medcal mages and ther extractons are almost smlar to that obtaned usng db2 17

18 wavelet at level-1. Hence DWT-BAT watermarkng algorthm s ndependent of mother wavelet and level of decomposton of the wavelet. Comparng Nose attacked watermarked mages n DWT-BAT wth other watermarkng algorthms proposed by us for medcal mage watermarkng s shown n fgure 25. From fgure 25 t s clear that DWT- BAT has produced exceptonally good watermarked medcal mages than the remanng wavelet based medcal mage watermarkng algorthms. Fgure 25. Nose attacked watermarked medcal mages usng (a) DWT based (b) RSA-DWT based (c) LWT-SVD based and (d) DWT-BAT based algorthms 6. CONCLUSION A DWT-BAT medcal mage watermarkng algorthm was proposed n ths research paper. Three dfferent types of medcal mages such as MRI, CT and US are used as cover mages and a patent mage s used as watermark to load the medcal mage. Medcal mage s loaded wth patent mage n wavelet transform doman. The amount of load from watermark s optmzed by usng BAT algorthm. Ths process of watermarkng helps n retanng the qualty of the medcal mage. Ths s mportant n many telemedcne applcatons. Testng of the proposed DWT-BAT watermarkng procedure s accomplshed by smulatng varous possble attacks on watermarked mages when transported through nternet. Expermental results show that the DWT-BAT algorthm demonstrates superor protecton on unsecured networks compared to normal DWT based watermarkng algorthms proposed earler. The expermental results prove ths fact vsually and mathematcally n ths paper. The proposed method does not put constrants on the resoluton of the watermarks used. The DWT-BAT watermarkng algorthm s also ndependent of mother wavelet and wavelet decomposton level. 18

19 REFRENCES: Cox I J, Kllan J, Leghton F T and Shamoon T, Secure Spread Spectrum Watermarkng for Multmeda. IEEE Transacton on Image Processng, vol.6, no,12, pp (1997). M.D. Swanson, M. Kobayash and A.H. Tewfk "Multmeda Data Embeddng and Watermarkng Technologes", Proceedngs of the IEEE, vol. 86, no. 6, pp (1998). Podlchuk, Chrstne I., and Wenjun Zeng. "Image-adaptve watermarkng usng vsual models." IEEE Journal on Selected Areas n Communcatons, vol.16, no. 4,pp (1998). Hartung, Frank, and Martn Kutter. "Multmeda watermarkng technques."proceedngs of the IEEE, vol. 87, no. 7 pp (1999). Haley, D., P. Jacobs, J. Smpson, and S. Doze. "An assessment framework for telemedcne applcatons." Journal of Telemedcne and Telecare 5, no. 3,pp (1999). Güler, Nhal Fatma, and Elf Derya Übeyl. "Theory and applcatons of telemedcne." Journal of Medcal Systems 26, no. 3 (2002): Haley, Davd, Rsto Rone, and Arto Ohnmaa. "Systematc revew of evdence for the benefts of telemedcne." Journal of Telemedcne and Telecare 8, no. suppl 1 (2002): 1-7. Smth, Anthony C., M. Bensnk, N. Armfeld, J. Stllman, and L. Cattery. "Telemedcne and rural health care applcatons." Journal of postgraduate medcne 51, no. 4 (2005). Anand, Deepth, and U. C. Nranjan. "Watermarkng medcal mages wth patent nformaton." In Engneerng n Medcne and Bology Socety, Proceedngs of the 20th Annual Internatonal Conference of the IEEE, vol. 2, pp IEEE, 1998 Zan, Jasn M., and Abdul RM Fauz. "Medcal mage watermarkng wth tamper detecton and recovery." In Engneerng n Medcne and Bology Socety, EMBS'06. 28th Annual Internatonal Conference of the IEEE, pp IEEE, Navas, K. A., and M. Saskumar. "Survey of medcal mage watermarkng algorthms." In Proc. Internaton Conf. Scences of Electroncs, Technologes of Informaton and Telecommuncatons, pp Jall, Zunera, and Anwar M. Mrza. "A revew of dgtal watermarkng technques for text documents." In Informaton and Multmeda Technology, ICIMT'09. Internatonal Conference on, pp IEEE, E.T. Ln and E.J. Delp "A Revew of Data Hdng n Dgtal Images", Proceedngs of the Image Processng, Image Qualty, Image Capture Systems Conference, PICS \'99, pp Boney, Laurence, Ahmed H. Tewfk, and Khaled N. Hamdy. "Dgtal watermarks for audo sgnals." In Multmeda Computng and Systems, 1996., Proceedngs of the Thrd IEEE Internatonal Conference on, pp IEEE, Wolfgang, Raymond B., Chrstne I. Podlchuk, and Edward J. Delp. "Perceptual watermarks for dgtal mages and vdeo." Proceedngs of the IEEE 87, no. 7 (1999): Nkolads, Nkos, and Ioanns Ptas. "Robust mage watermarkng n the spatal doman." Sgnal processng 66, no. 3 (1998): N.Venkatram, L.S.S.Reddy, P.V.V.Kshore, Multresoluton Medcal Image Watermarkng for Telemedcne Applcatons, CT Internatonal Journal of Dgtal Image Processng, Vol(6),Issue 1, Jan 2014,pp6-15. N.Venkatram, L.S.S.Reddy, P.V.V.Kshore, RAS-DWT based medcal mage watermarkng for telemedcne applcatons Journal of Theoretcal and Appled Informaton Technology, An Internatonal Journal, Vol(65),Issue 2, July ISSN: E.T. Ln and E.J. Delp "A Revew of Fragle Image Watermarks", Proceedngs of the Multmeda and Securty Workshop at ACM Multmeda\'99, pp Coatreux, G., H. Matre, B. Sankur, Y. Rolland, and R. Collorec. "Relevance of watermarkng n medcal magng." In Informaton Technology Applcatons n Bomedcne, Proceedngs IEEE EMBS Internatonal Conference on, pp IEEE, Gakoumak, A., S. Pavlopoulos, and D. Koutours. "A medcal mage watermarkng scheme based on wavelet transform." In Engneerng n medcne and bology socety, Proceedngs of the 25th annual nternatonal conference of the IEEE, vol. 1, pp IEEE,

20 Irany, Behrang Mehrbany, Xn Cndy Guo, and Dmtros Hatznakos. "A hgh capacty reversble multple watermarkng scheme for medcal mages." In Dgtal Sgnal Processng (DSP), th Internatonal Conference on, pp IEEE, Lavanya, A., and V. Natarajan. "Watermarkng patent data n encrypted medcal mages." Sadhana 37.Part 6 (2012). Inoue, H., Myazak, A., Yamamoto, A., & Katsura, T. (1998, October). A dgtal watermark based on the wavelet transform and ts robustness on mage compresson. In Image Processng, ICIP 98. Proceedngs Internatonal Conference on (Vol. 2, pp ). IEEE. Wakatan, Akyosh. "Dgtal watermarkng for ROI medcal mages by usng compressed sgnature mage." In System Scences, HICSS. Proceedngs of the 35th Annual Hawa Internatonal Conference on, pp IEEE, X.-S. Yang, A New Metaheurstc Bat-Inspred Algorthm, n: Nature Inspred Cooperatve Strateges for Optmzaton (NISCO 2010) (Eds. J. R. Gonzalez et al.), Studes n Computatonal Intellgence, Sprnger Berln, 284, Sprnger, (2010). Xn-She Yang and Amr H. Gandom, Bat Algorthm: A Novel Approach for Global Engneerng Optmzaton, Engneerng Computatons, Vol. 29, Issue 5, pp (2012). Altrngham, J. D.: Bats: Bology and Behavour, Oxford Unvesty Press, (1996). Kshore, P. V. V., & Rajesh Kumar, P. (2012). A Vdeo Based Indan Sgn Language Recognton System (INSLR) Usng Wavelet Transform and Fuzzy Logc. Internatonal Journal of Engneerng & Technology ( ), 4(5). Kshore, P. V. V., & Kumar, P. R. (2012). A Model For Real Tme Sgn Language recognton System. Internatonal Journal of Advanced Research n Computer Scence and Software Engneerng, vol.2,(6). Kshore, P. V. V., Kumar, P. R., Kumar, E. K., & Kshore, S. R. C. (2011). Vdeo Audo Interface for Recognzng Gestures of Indan Sgn. Internatonal Journal of Image Processng (IJIP), 5(4), 479. N.Venkatram, L.S.S.Reddy, P.V.V.Kshore, Blnd Medcal Image Watermarkng wth LWT SVD for Telemedcne Applcaton, WSEAS Transactons on sgnal processng, Vol(10),Issue 2, June