VOL. 5, NO. 12, December 2015 ISSN ARPN Journal of Science and Technology All rights reserved.

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1 Moded Thomson and Tau based Imulse Nose Detecto G. Maagatham S. Md Mansoo Room 3 A. Sasthadev Assstant Pofesso Deatment of Electoncs and Communcaton Unvesty College of Engneeng Dndgul Inda Assstant Pofesso Deatment of Electoncs and Communcaton Thagaaa College of Engneeng GST Road Thuaankundam Madua Taml Nadu Inda 3 Reseach Schola Deatment of Electoncs and Communcaton Thagaaa College of Engneeng GST Road Thuaankundam Madua Taml Nadu Inda gmaagathamganesan@gmal.com smmoom@tce.edu ABSTRACT Pesevng edges and detals n the ocess of mulsve nose flteng s an motant oblem. To avod mage smoothng only couted xels must be flteed. Many flteng technques exst fo mulse nose emoval wth vaety of nose detecton methods. An analyss of such detecton methods wth vaous levels of nose shows the need of a new mulse nose detecto. In ode to denty the couted xels a new mulse detecto based on a moded Thomson Tau technque s oosed. Exemental esults show that the oosed method woks at all levels of nose couton. Keywods: Detecto mulse nose gaussan nose fltes thomson and tau estmaton. INTRODUCTION The couton by mulse nose s a fequently encounteed oblem n mage acquston and tansmsson. Attenuaton of nose and esevaton of detals ae usually two contadctoy asects of mage ocessng. Nevetheless both of them ae motant to subsequent ocessng stages []. Medan flte and ts vaants [-3] ae the ealest oosed methods fo mulse emoval. Howeve snce such fltes teat all xels of an mage n the same way they tend to mody xels that ae undstubed by nose. Theefoe late methods [-8] ae of usually two stage wth an mulse detecton stage at whch mulses ae located and an mulse flteng stage at whch only the located mulses ae flteed thus the modcaton of good xels ae avoded. The efomance of such two-staged fltes geatly deends on the effcency of the mulse detecto. An deal mulse detecto has to exactly ma the oston of all mulses wthout any msdetecton. The comutaton tme of an mulse detecto s also an motant facto of concen snce t s ust the ntal stage n flteng. Though vaous Imulse detectos avalable n the lteatue detect mulses most often they ethe msdetect non mulsve xels as mulses o comutatonally exensve. In ths ae an mulse detecto based on the moded Thomson and Tau technque [9] has been oosed along wth the efomance analyss of vaous mulse detectos. The oosed mulse detecto s comaed wth the exstng mulse detecton schemes n tems of level of exact detecton and msdetecton. The ae s oganzed as follows: Nose n an mage descbes the nose model consdeed. Some of the exstng mulse detectos ae befed n mulse detectos - an ovevew. The oosed mulse detecto s exlaned n oosed methodology. nally analyss and conclusons based on smulated exemental esults ae esented n exemental analyss.. Nose n an Image Consde an mage I of sze obsevaton mage of same sze. M N and an I () Whee s mulse nose wth andom values. The nose s assumed to be unomly dstbuted wth a obablty N I Wth Wth Pobablty () Whee Pobablty =..M and = N and z / M N. o 8 bt mages a xel s couted t s elaced by ostve o negatve mulse values. Conventonally mulse nose assumes fo a negatve mulse and 55 fo a ostve mulse. In geneal the amltude of mulses ae not fxed but ae allowed to vay between the ostve and negatve eaks. But hee fxed amltude and andom dstbuton of mulses s assumed n the obseved couted mage.. IMPULSE DETECTORS-AN OVERVIEW In ode to descbe how the mulse detectos wok on a couted mage an ovevew of mulse detectos s esented. Consde a wndow W of sze (K+)(K+) centeed aound the xel x of concen ostoned at () such that x... x... x } (3) { k k k k The ank of evey xel R s defned as the oston the xel occues when the elements of the wndow ae soted n ascendng ode. Let the medan of the wndow be gven by 67

2 m medan () The absolute devaton of evey xel fom the medan s denoted as d x m (5) Each mulse detecto makes use of few of these aametes n mang the oston of mulses.. Detecto based on Rank Ode Ctea Ths detecto s called as Dfeental Rank Imulse Detecto (DRID) []. Ths detecto makes decsons based on both the ank of the xel and the absolute devaton of the xel fom the medan of the wndow as M t (3). Detecto based on Pogessve Swtchng Medan lte The mulse detecto used n ogessve swtchng medan flte [] s based on the absolute devaton of evey xel fom the medan of the set. The flag s set the absolute devaton s geate than a secc theshold t as gven below. M t (6). Detecto based on PWMAD The mulse detecto usng Pxel Wse Medan Absolute Devaton (PWMAD) [6] of the wndow W s gven as PWMAD medan d ) medan( x m ) (7) ( A xel n the couted mage s as an mulse d n PWMAD n t (8).3 Detecto based on ROAD Statstcs Rank odeed absolute dfeences (ROAD) [] statstc s defned as ROAD m x m x whee <m<7 n a 3x3 neghbohood and (9) th ( x) smallest d fo y W () xy whee x y () d xy s the dfeence n the xel values of xels x and y. The outut of the mulse detecto s dctated by a theshold t as.5 Detecto based on Imoved Medan lte In ths algothm [3] the nut mage s fst convolved usng fou kenels K = to and can be defned as K = K 3 = K = K = A aamete s obseved such that = mn { K 3 } () Whee s the convoluton oeato? The s comaed wth the theshold to detect the mulse as show below. t (5).6 Accuate Nose Detecto fo Imulse Nose Accuate nose detecto conssts of two systems. st system detemnes the locaton of mulsve nose by usng two medan fltes wth dfeent szes of wndows accodng to a new flag mage. The second system vees the weathe each nose xel detemned by the fst system s an mulse o not. 3. PROPOSED METHODOLOGY In an mage couted by fxed mulse nose a statstcal ocedue fo elmnatng mulsve data fom a samle data of wndow of tycally 7 7 s nvestgated. ROAD t () The couted mage s consdeed block by block athe xel by xel. Blocks ae allowed to ovela atally fo bette efomance. The mean and standad 68

3 devaton of the samle and S ae calculated and then the mulses ae located based on Moded Thomson and Tau Technque. o the atcula wndow W the mean and the standad devaton ae calculated as mean W S N Whee N s the numbe of elements n the set? (6) (7) The devaton ( ) of evey xel ( ) fom mean s then detemned a (8) These devatons ae standadzed as (9) S S nally the lagest s comaed wth that of the tabulated tau values n Table. If t s geate than the tabulated value then the xel s maed as an mulse. Now the mean and devaton of the set elmnatng the xel coesondng to the mulse s ecalculated and the ocedue s eeated teatvely untl all the values ae less than the tabulated tau value. Evey teaton checks fo the esence of an mulse Snce t consdes nut mage as atally ovelang blocks the comutatonal comlexty s O ((N-m) ^) whee m s the ovela allowed. When m= the comutatons become O (N^) whch s same as that of othe detectos. Ths bnay flag matx s used fo estmatng the level of couton and also n flteng of mulses. 3. Poosed Imulse Nose Level Estmaton Technque In a couted mage the level of mulse nose couton s to be estmated. Cetan aametes of fltes lke the wndow o kenel sze theshold values etc ae deendent on the nose level. Hence a new nose level estmaton scheme fo mulse nose couted mages s oosed. The oosed nose level estmaton technque s based on the flag matx obtaned fom the mulse detecton stage. The accuacy of estmaton hghly deends on the elablty of flag matx. Geneally the mulse detectos efom well at hghe nose levels whee the numbe of msdetectons deceases. Hence the obseved mage s futhe couted by mulse nose as Only one mulse could be detected at a tme. The seach fo an mulse could be caed ove block by block. o bette efomance the mage s consdeed as ovelang block of data by whch the msdetectons ae educed. Hence the oosed technque eques elatvely less comutatonal tme and calculatons. The oosed mulse detecton technque well suts n dentyng the mulses n the nosy envonment. The comutatonal comlexty of the oosed mulse detecto s low when comaed to othe state of at fltes. Table : Standad Tau values N Tau N Tau ( ) wth obablty Y( ) wth obablty () Whee s the nose fom a contolled souce? The oston of these addtve mulses s eesented by a bnay flag matx f n whch eesents the esence of an mulse. Ths stochastc nose added mage s gven as nut to the mulse detecto a flag matx f s obtaned. Ths flag matx s efned so as to exclude the mulses that ae ntentonally added to the obseved mage and s gven as f () Whee s the bnay flag matx coesondng to the oston of mulses n the obseved mage? When the addtve mulses ovela wth the actual mulses the accuacy of the estmate s deceased. 69

4 Hence the ocess of addng nose and detectng the ostons s eeated fo k teatons the outut of each teaton beng eesented as k. The Comason of Imulse Detectos fnal flag matx s obtaned fom the bnay summaton of all these k flag matces. ^ f ^ ^ ^ f f... f k ^ f k () Pecentage of coect detecton 8 6 Rank Ode lte PSM PWMAD Unvesal Imulse Detecto Imoved Medan lte Accuate Nose Detecto Poosed Detecto A facto called Nose Count (NC) whch s the numbe of mulses n the couted mage s defned. It s deved fom the flag matx and s gven as S S NC (3) Nose Pecentage gue : Comason of mulse detectos-n mages couted wth mulse nose alone The estmate fo nose level N s based on the NC. The level s calculated as NC N () S S whee S and S eesent the dmensons of the mage.. EPERIMENTAL ANALYSIS The oosed mulse detecto based on moded Thomson and Tau technque s tested fo mages couted wth only mulse nose and fo mages couted wth mxed nose also. The efomance of the oosed mulse detecto n comason wth othe detectos on mages couted wth only mulse nose s lotted n gue-. The oosed technque faly detects the mulses wth the least comutatonal tme. The Nose estmaton scheme s also tested fo mulse nose couted mages and mxed nose couted mages. Table- and gue- show the dfeence between actual and estmated nose level. The mulse nose level estmaton s consstent nste of nose levels and mage detals as nfeed fom Table 3. gue-3 lots the estmaton eo ecentage aganst the numbe of teatons emloyed n estmatng the nose vaance. It could be seen that at least 3 teatons s necessay fo exact estmaton of nose vaance. The mulse nose level calculaton s exemented on mages couted only wth mulse nose and on mages couted wth mxed nose. The esults valdate that the estmaton s elable untl the mulse detecto s elable gue : Nose estmaton at vaous nose levels Table : Eo n nose estmaton fo vaous mages at vaous nose levels Inut Nose Level Images Eo n Estmaton Tle lowes Ccut Eght Pout Pond Temle Mandll Test Llly

5 Eo n Estmaton gue 3: Eo n nose estmaton fo vaous mages at vaous nose levels Table 3: Nose estmaton fo dfeent mages Image Actual Nose level Estmated Nose Level Lena 5 % 9.85 % Cameaman 5 % 9.93 % Bdge 5 % 5.38 % Pees 5 % 9.85 % Mandll 5 % 5.8 % % Eo Inut Nose Level Te lowes Ccut Eght Pout Pond Temle Pefomance Analyss of Estmaton Stategy No. of Iteattons gue : Pefomance of estmaton stategy vesus teatons nvolved 5. CONCLUSION Ths eseach wok oosed a Moded Thomson and Tau Technque to detect the mulse nose esecally when the mage s affected at hgh densty. The ablty of the Moded Thomson and Tau Technque towads detectng mulse nose s demonstated by comang vaous detectos. REERENCES [] Rafael C. Gonzalez and Rchad E. Woods Dgtal mage ocessng nd Edton Pentce- Hall. [] N. C. Gallaghe J and G.W. Wse A theoetcal analyss of the oetes of medan fltes IEEE Tans. Acoust. Seech Sgnal Pocessng vol [3] S.J.Ko and Y.H Lee Cente Weghted Medan ltes and the Alcaton to Image Enhancement IEEE Tans. Ccuts Syst. vol 38 no.9 Set. 99. [] E. Abeu and S. K. Mzta A Sgnal-Deendent Rank Odeed Mean (SD-ROM) lte A New Aoach fo Removal of Imulses fom Hghly Couted Images IEEE 995. [5] Davd Zhang and Zhou Wang Image Infomaton Restoaton Based on Long-Range Coelaton IEEE Tansactons on Ccuts and Systems fo Vdeo Technology vol. no. 5 May. [6] Vladm Cnoevc Von Senk and Želen Tovsk Advanced Imulse Detecton based on Pxel-Wse MAD IEEE Sgnal Pocessng Lettes vol. no. 7 July [7] Raymond H. Chan Chung-Wa Ho and Mla Nkolova Salt-and-Pee Nose Removal by Medan-Tye Nose Detectos and Detal- Pesevng Regulazaton IEEE Tansactons on Image Pocessng vol. No. Octobe 5 [8] P.Badulescu and R. Zacn() A two-state swtched-medan flte CAS Poceedngs vol [9] Alan C. Acock A Gentle Intoducton to Stata Second Edton A Stata Pess Publcaton Texas. [] Z. Wang and D. Zhang Pogessve swtchng medan flte fo the emoval of mulse nose fom hghly couted mages IEEE Tans. Ccuts Syst. vol Jan [] Roman Ganett Tmothy Huegech Chales Chu Wene He A Unvesal Nose Removal Algothm wth an Imulse Detecto IEEE Tansactons on Image Pocessng vol. No. Novembe 5. [] Igo Azenbeg and Constantne Butakoff Effectve Imulse Detecto Based on Rank-Ode Ctea IEEE Sgnal Pocessng Lettes vol. no. 3 Mach. [3] Son Zocan Imoved Medan lte fo Imulse Nose Removal TEELSIKS Octobe 3. 65