APPLICATION OF COARSE TO FINE LEVEL SET SEGMENTATION IN SATELLITE IMAGES

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1 APPLICATION OF COARSE TO FINE LEVEL SET SEGMENTATION IN SATELLITE IMAGES 1 DEEPA VARGHESE, 1 P. SELVARANI, Dr. V. VAITHIYANATHAN, 3 R. D. SATHIYA 1 Student, School of Computng, SASTRA Unversty Assocate Dean of Research, School of Computng, SASTRA Unversty 3 Assstant Professor, School of Computng, SASTRA Unversty Thanjavur, Tamlnadu, Inda Emal: 1 varghesedeeps@gmal.com, 1 selvaran.patnak@yahoo.co.n, vvn@t.sastra.edu, 3 sathya@t.sastra.edu ABSTRACT Segmentaton of vegetated areas s nevtable n precson agrculture and has hgh mportance n urban area wth socal and envronmental aspects. Ths paper addresses the segmentaton of fused hgh resoluton multspectral satellte mages nto dstnct regons such as vegetaton, buldngs and barren land. Even though the IHS based fuson of satellte magery mproves the vsual nterpretaton, t results n color dstorton whch can be nullfed usng vegetaton ndexes(vi).the vegetated area can be depcted usng hgh resoluton normalzed vegetaton ndex and to detect the dstrbuton of vegetated area, sol classes, buldngs and barren land. For that the coarse-to-fne level set method s used. Undecmated wavelet transform s adopted to separate focused areas from the background. Homogenety metrc s used to measure the varaton nsde and outsde the contours. The weght dstrbuton rato s proposed to adaptvely tune the relatve weght of the features. Based on the homogenety metrc and the weght dstrbuton rato, a novel energy functonal s developed to solve the contour extracton problem and a coarse-to-fne scheme s appled to progressvely extract contours n fner scale whch also reduces the computatonal burden. Keywords: Contour Extracton, Homogenety Metrc, Level Set Methods, Intensty-Hue-Saturaton (IHS) Transform, Vegetaton Enhancement 1. INTRODUCTION Segmentaton of fused remotely sensed mages provdes exact delneaton of dfferent landscape patches. The accurate segmentaton of vegetaton helps n precson agrculture, fndng rare speces of plants n forest area, unauthorzed plantaton n nteror forest and mappng of urban green for effectve management and protecton. Images from satelltes wth enhancement usng the advanced technologes of remote sensng provde detaled and accurate nformaton about land use for management and plannng. Remote sensng data and ts software processng represents powerful tool for creaton of thematc maps. Smultaneously obtaned remote low resoluton multspectral (MS) mages and hgh resoluton panchromatc (PAN) mages from earth observaton satelltes has to be fused to get a hgh resoluton mage[1][]. Hgh resoluton multspectral mages 7 are effcent for classfyng both homogeneous and heterogeneous objects. A large varety of vegetated mages are avalable from satelltes and we need effcent methods to extract the vegetaton. For obtanng the hgh resoluton mage the most commonly used fuson technque s ntensty hue saturaton (IHS) whch make use of three bands of multspectral mage but when the fourth band NIR s ncluded GIHS [1] s used. But nether IHS nor GIHS produce an mage wthout dstorton, so an enhancement step s to be ncluded. A method of weghted average s descrbed [13] whch restran spectral degeneraton. As the focus s on vegetated area, an enhancement technque usng vegetaton ndex s used [4]. In ths paper hgh resoluton vegetaton ndex s used and the resultant enhanced vegetated mages are used for segmentaton [1]. The coarse to fne segmentaton method nclude a number of steps whch results n the exact contours [5].

2 The relevance of ths paper s to have a three dmensonal segmentaton whose mage s obtaned by applyng a fuson algorthm whch safeguards the spatal propertes of PAN and spectral propertes of MS mage. The fuson s done wth GIHS method wth some spectral adjustment [1]. After enhancng, Intensty dfference s calculated usng haar flter and passed to the homogenety metrcs [5]. The homogenety metrc measures the varatons of mages nsde and outsde contours. Based on the homogenety metrcs dscrmnatve ablty s also calculated. Weght dstrbuton rato s calculated to tune the relatve weght of the mages. The result of homogenety metrcs and the weght dstrbuton rato leads to novel energy functon. The purpose of novel energy functon s to solve contour extracton problem. Fnally coarse to fne level set s mplemented by Euler Lagrange equaton to reduce the computaton cost. Ths paper s organzed as follows. Secton s dvded nto three whch dscusses the related works. Secton 3 presents the archtecture and model. Secton 4 s about the problem defnton. Secton 5 presents the mplementaton of the proposed algorthm and the performance analyss. Secton 6 contans the concluson.. RELATED WORKS.1. FUSION AND SEGMENTATION Varous fuson methods based on PCA, Brovey, wavelet and IHS exst for obtanng a hgh multspectral mage resoluton mage.as we consder vegetated area, the fuson should be free from color dstorton and the latest IHS technques proposed by M. Mezouar, N. Taleb [1] helps n achevng the same. And for segmentaton [10] tells about a herarchcal method of segmentaton and [11] of a regon based method. Ths paper proposes a new approach whch makes use of Euler Lagrange equatons [5]... IHS FUSION AND ENHANCEMENT IHS fuson s most commonly used fuson technque and t uses an RGB mage consstng of dstant bands and transforms them nto the IHS space, and the ntensty component s replaced by PAN and s transformed back to orgnal RGB space. The IHS fuson for each pxel s dscussed n paper [] [3]. R, G and B are the correspondng values to RGB n the fused mages. R' R G' = G (1) B' B From the above equaton a much more effcent method Fast IHS (FIHS) s computed. Even though FIHS fuson provdes the full detals of PAN, ntroduces certan dstorton due to the dfference n PAN and Intensty (I). Two algorthms exsts whch reduces the dfference ( ) by generatng an I component close to PAN. In ths the Near Infra Red (NIR) component s added and the frst method s termed as Generalzed IHS(GIHS) whose ntensty value s calculated by I=(R+G+B+NIR)/4 () and the second method s spectral adjustment IHS whch nclude a weghtng coeffcent whch s related to the spectral characterstcs of the sensors[14]. The ntensty calculaton for SAIHS s termed as I=(R+aG+bB+NIR)/3 (3) where 0.75 and 0.5 corresponds to a and b, respectvely, are found to be sutable for fuson. Next step s the enhancement of the vegetated area, but before enhancement the vegetated area has to be detected and s performed wth hgh resoluton normalzed ndex [1] [4]. HRNDVI = NIR-R (4) NIR+R-B+4PAN-G and If HRNDVI s greater than 0.15 the green bands are enhanced usng G'' B'' = (5) s set to 0.5 whch gves a natural look n the vegetated areas. The fused bands are computed usng R' G' B' NIR' = Where 0. 6 G' 4 B' 4 R 4 G 4 B 4 NIR 4 (6) 8

3 .3. AREA EXTRACTION AND NOVEL ENERGY FUNCTIONAL MODEL Here we extract the object from background by usng undecmated wavelet transform (UWT) [1]..The undecmated wavelet transform s selected because t s shft nvarant and produces sub bands of same sze as the nput mage. There are three types of undecmated wavelet transform (Dscrete cosne transform). ) Hough Transform ) Haar flter banks ) Daubeches The haar flter banks are used to calculate the ntensty dfference between object and the background [5], [6]. Homogenety metrc s used to measure the varaton of the mages nsde and outsde contours. So ths homogenety s calculated based on the ntensty dfference usng haar flter. The homogenety metrc of d n regon k (k=0,1,)s defned by E (d, k ) = (d (x,y)-d k ) dxdy (7) The dscrmnatve ablty of d can be measured by E, 0 0 d, c E, 1 E, 0 (8) Where d k s the mean value of d over regon k. Weght dstrbuton rato s used to tune the relatve weght of the features. And ths weght dstrbuton rato s calculated based on dscrmnatve ablty component. d, c 4 ( d j 1 ( d, c) j, c) (9).4. COARSE TO FINE LEVEL SET SCHEME The purpose of ths scheme s to reduce the resoluton level at a tme. It conssts of three sub modules Coarse Scale Extracton The purpose s to mnmze the energy functon, whch s the summaton of weghted homogenety metrc of four components n a regon. The four components are haar flter, homogenety metrcs, and dscrmnatve ablty component and weght dstrbuton rato F N (c)= H dxdy, c ( d d 1 4 ) H dxdy d d H + c 1, 0 1 dxdy (10).4.. Fne scale Contour Extracton Contour poston constrant s used to reduce the contour evoluton space to a small regon t s obtaned by the followng equaton R x, y d exp x, y, Euler Lagrange Numerc Soluton (11) In order to mnmze the unform level set functonal, we deduce the assocated Euler Lagrange [5] [7] [8] equaton for by ntroducng the artfcal varable t to.the Equaton R dv, c d d1, c d d 4 (1) t 1 Fne scale can be mplemented by Euler-Lagrange equaton. It solves the contour extracton problem. 3. ARCHITECTURE AND MODELING Many a tme s data gathered from remote sensng satelltes provdes excellent possbltes for mappng, montorng, measurng, and managng varous earth surface features. Ths helps n areas where only lmted feldwork s possble. The archtecture and modelng of the proposed algorthm s shown below. The step by step process of fuson and the segmentaton s shown n fgure. It begns wth the panchromatc mage, multspectral mage of the same locaton. The IHS fused mage, the vegetaton enhanced mage and the segmentaton usng coarse to fne level set s shown n fgure. 9

4 Algorthm for fuson and enhancement Step 1: Input the Enhanced mage. Step : Elmnate nose from the mage. Step 3: Dstngush mage from background usng haar flter Step 4: Calculate homogenety metrc and weght dstrbuton rato. Step 5: Based on ths novel energy functonal calculated. Step 6: Segment the mage nto dstnct regons lke resdental area, vegetaton and barren land. Algorthm for coarse-to-fne-segmentaton 5. IMPLEMENTATION AND PERFORMANCE ANALYSIS Fg.1 Block dagram for Fuson and Segmentaton Fgure 1 shows the flow of the algorthm for fusng mages and segmentaton nto dstnct regons. 4. ALGORITHM Gven satellte magery the target s to fuse the mage, enhance the vegetaton and segment usng Euler Lagrange. Step 1: Input panchromatc and multspectral mage. Step : Perform IHS fuson where the I value s calculated usng (3) and value s dfference of PAN and I. Step 3: Calculate the HRNDVI ndex. Step 4: Enhance the Vegetaton. The two algorthms one for fuson and another for segmentaton s mplemented usng MATLAB 7 and JAVA 6 respectvely. The performance analyss of fuson s shown n table 1. And the vegetated area s accurately segmented where the vegetaton enhancement plays a vtal role. Removal of nose and low resoluton mage generaton are done by haar wavelet transform. The advantage of haar flters s referred [6]. The segmentaton of vegetaton s done by passng the green ntensty pxel value as the nput to the Euler Lagrange numerc soluton and ten teratons are done for obtanng the segmentaton. Euler Lagrange s manly for segmentng D objects. As the buldngs n the mage appear as D t can be drectly appled to Euler Lagrange and results n 3D objects. The dfference of the orgnal mage and the combnaton of vegetated area and buldng wll gve the barren land. The number of teratons s eght for both buldngs and barren land. In objectve analyss, the method n [7] s adopted to evaluate the accuracy of extracted contours. The success score s the number of pxels contaned n regons both nsde groundtruth and extracted contours dvded by the regons nsde the ground-truth or the extracted contours.and the success score s near to 1 for all the segments. Ths proves the effcency of segmentaton 30

5 Parameters IHS Fuson Mean Input Mean Output Relatve Bas Relatve Varance Standard Devaton Correlaton SAM UIQI ERGAS Table 1. Performance Measures 6. CONCLUSION Ths paper presents a new approach for segmentng the satellte mages. The capablty of ths method s apprecable as t s computatonally effcent and provded good results n terms of objectve and subjectve evaluatons. As the areas are so accurately segmented the paper can be extended for countng the number of trees n a plantaton [9], for segmentng dfferent types of herbs and can be used for urban development and precson agrculture. REFERENCES [1] M. l Mezouar, N. Taleb, K. Kpalma, and J. Ronsn, An IHS-based fuson for color dstorton reducton and vegetaton enhancement n IKONOS magery, IEEE Transactons on Geosc, and Remote Sensng, vol. 49 (5), pp.: , DOI: 10.1 Fg. (a) Multspectral Image (b) Panchromatc Image (c) SAIHS Fused Image (d) Vegetaton Detecton (e) Vegetaton enhanced Image (f) Buldng (g) Vegetaton Area [] T.-M. Tu, P. S. Huang, C.-L. Hung and C.-P. Chang, A fast ntensty hue-saturaton fuson technque wth spectral adjustment for IKONOS magery, IEEE Geosc. Remote Sens. Lett., vol. 1, no. 4, pp , Oct [3] J. A. Malpca, Hue adjustment to IHS pansharpened IKONOS magery for vegetaton enhancement, IEEE Geosc. Remote Sens. Lett. vol. 4, no. 1, pp. 7 31, Jan

6 [4] T.-M. Tu, H.-T. Lu, Y.-C. Chang, J.-C. Chang and C.-P. Chang, A new vegetaton enhancement/extracton technque for IKONOS and QuckBrd magery, IEEE Geosc. Remote Sens. Lett. vol. 6, no., pp , Apr [5]. Qzh Xu, Bo L, Zhaofeng He, and Chao Ma, Multscale Contour Extracton Usng a Level SetMethod n Optcal Satellte Images, IEEE Geosc. Remote Sens. Lett. vol. 8, no. 5, Sept 011 [6]. J. L. Starck, J. Fadl, and F. Murtagh, The undecmated wavelet decomposton and ts reconstructon, IEEE Trans. Image Process., vol. 16, no., pp , Feb [7]. R. de Lus-Garcıacute;a, R. Derche, and C. Alberola-López, Texture and color segmentaton based on the combned use of the structure tensor and the mage components, Sgnal Process., vol. 88, no. 4, pp ,Apr /TGRS (May 011). [8].Y. N. Law, H. K. Lee, and A. M. Yp, A multresoluton stochastc level set method for Mumford Shah mage segmentaton, IEEE Trans. ImageProcess., vol. 17, no. 1, pp , Dec. 008 [9] Vbha L,P Deepa Shenoy,Venugopal K R,L M Patnak Robust Technque for segmentaton and countng of trees from remotely sensed data, IEEE Internatonal Advance Computng Conference,March 009 [10] Felpe Calderero,Ferran Marques, Javer Marcello, Francsco Eugeno Herarchcal segmentaton of vegetaton areas n hgh spatal resoluton mages by fuson of multspectral nformaton IEEE IGARSS,009 [11] Dr.S.V.Kasmr Raja, A.Shak Abdul Khadr, Dr.S.S.Raz Ahamed. Movng Toward Regon-Based Image Segmentaton Technques: A Study Journal of Theoretcal and Appled Informaton Technology. pp.81-87, 009 [1] N.Ln, W.Yu, and J.S Duncan, Combnatve mult-scale level set frame-work for echocarographc mage segmentaton, Med.Image Anal.,vol.7,no.4,pp ,Dec.003 [13] Xaofe Wen, Image Fuson Based on Improved IHS Transform wth Weghted Average Internatonal Conference on Computatonal and Informaton Scences DOI /ICCIS [14] Yonghyun Km, Yangdam Eo, Younsoo Km, and Yongl Km Generalzed HIS-Based Satellte Imagery Fuson Usng Spectral Response Functons ETRI Journal,Volume 33,Number 4,August

7 AUTHOR PROFILES: Deepa Varghese receved masters degree n Informaton Technology and Management from ANNA UNIVERSITY n 00.She worked as lecturer n SCMS School of Engneerng And Technology, Kerala from Currently, she s pursung M.Tech n computer scence and Technology from SASTRA UNIVERSITY. Her nterests are n mage processng, data mnng and computer networks. P. Selvaran receved B.Tech n Informaton Technology from Mookambka College of engneerng, afflated to ANNA UNIVERSITY. Pursung M.Tech n SASTRA UNIVERSITY. Dr. V. Vathyanathan Assocate Dean of Research, Department of ICT n SASTRA UNIVERSITY. Hs nterests are n Soft Computng, mage processng, cryptography. Hs ongong research project ncludes Panchromatc Images, Image Segmentaton usng Level sets, and actve contour models. Sathya R.D receved M. Tech from SASTRA UNIVERSITY and s currently workng as the Assocate Professor of SASTRA UNIVERSITY. Her nterests are n mage processng, network securty and cryptography. 33