Recognition of Shapes for Object Retrieval in Image Databases by Discrete Curve Evolution and Two Consecutive Primitive Edges

Transcription

1 Poceedngs of the Intenatonal MultConfeence of Engnees and Compute Scentsts 009 Vol I IMECS 009 Mach Hong Kong Recognton of Shapes fo Object Reteval n Image Databases by Dscete Cuve Evoluton and Two Consecutve Pmtve Edges Tan-Luu Wu and J-Hwe Hong Abstact- Ths pape pesents the ecognton of shapes fo object eteval n mage databases usng skeleton-based and contou-based epesentaton by dscete cuve evaluaton and two consecutve pmtve edges. Humans tend to use hgh-level concepts n eveyday lfe. Object segmentaton and ecognton s the pmay step of compute vson to acheve mage eteval of hgh-level mage analyss. Contou-based and skeleton-based epesentatons ae mpotant fo object ecognton n dffeent aeas. In compang the contou-based appoaches wth the skeleton-based appoaches fo object epesentaton the contou-based s moe senstve to nose than a skeleton-based appoach based on a good skeleton punng method but a ough shape classfcaton can be pefomed snce the obtaned skeletons do not epesent any shape detals. In ths pape we poposed a novel method to ntegate the contou-based appoaches wth skeleton-based appoaches fo object epesentaton. The contou-based and skeleton-based epesentatons ae based on the popol of two consecutve pmtve edges method and dscete cuve evoluton method espectvely. Expemental esults demonstate that the pefomance of the poposed algothm s supeo to Tosello and Hancock s method [7] n tems of eteval accuacy. Index Tems: Keywods: Skeleton shape smlaty measue vsual pats dscete cuve evoluton I. INTRODUCTION In the past contou and skeleton wee usually used to analyze and epesent the shape of objects. Contou-based s an mpotant aspect of human vsual pecepton. Polygonal appoxmaton has been a vey popula shape epesentaton technque. It not only tsfactoly epesents a shape but also sgnfcantly educes the amount of pocessng data fo futhe applcatons. Theefoe many shape ecognton (matchng methods though polygonal appoxmaton [] have been poposed. Howeve some conventonal methods ae somewhat senstve to non-consstent esults of polygonal appoxmaton. Fo example the method [] usng attbuted stng matchng cannot accuately defne the edt dstance (cost fo nseton and deleton opeatons. Latck and Lakampe [] poposed a convexty ule fo shape decomposton based on dscete contou evoluton. They concentate some of decomposton of D objects nto meanngful vsual pats and poposed a contou evaluaton Manuscpt eceved Januay Tan-Luu Wu s wth the Electonc Engneeng Natonal Knmen Insttute of Technology Tawan R.O.C. (coespondng autho to povde phone: ; fax: ; e-mal:wtlu@kmt.edu.tw. J-Hwe Hong s wth the Electonc Engneeng Natonal Knmen Insttute of Technology Tawan R.O.C. (e-mal:hong@kmt.edu.tw. method fo dentfyng the vsual pat whethe t s a sgnfcant convex pat o not. The skeleton s anothe mpotant method fo object epesentaton and ecognton. Skeleton-based epesentatons ae the abstactons of objects whch contan both shape featues and topologcal stuctues of ognal objects. Many eseaches have made effots to ecognze the genec shape by matchng skeleton stuctues epesented by gaphs o tees [3]. Unfotunately these appoaches have only demonstated the applcablty to objects wth smple and dstnctve shapes and theefoe cannot be appled to moe complex shapes lke shapes n a MPEG-7 data set. The most common appoaches fo ovecomng skeleton nstablty ae based on skeleton punng. Punng can ethe be pefomed mplctly as a post pocessng step o ntegated n the step of skeletonzaton computaton. In geneal the skeletonzaton algothms can boadly be classfed nto fou types: ( the fst type s thnnng algothms such as those wth shape thnnng and the wave font/gassfe tansfom. These algothms teatvely emove bode ponts o move to the nne pats of an object n detemnng an object s skeleton; ( the second type s the categoy of dscete doman algothms based on the Voono dagam. These methods seach the locus of centes of the maxmal dsks contaned n the polygons wth vetces mpled fom the bounday; (3 the thd type of algothms s to detect dges n a dstance map of bounday ponts. Appoaches based on dstance maps usually ensue accuate localzaton but does not guaantee that the skeleton can connect completely; (4 the fouth type of algothms s based on mathematcal mophology. Usually these methods can localze the accuate skeleton but may not guaantee the connectvty of the skeleton. In ths pape we poposed a method to ntegate the contou-based appoaches wth skeleton-based appoaches fo object epesentaton. The contou-based and skeleton-based appoaches ae based on the poposed two consecutve pmtve edges method and the dscete cuve evoluton method espectvely. To ovecome skeleton nstablty based on skeleton punng the poposed skeleton punng appoaches can pune the edundant skeleton banches based on the contou estmaton and pe-selecton of the mplct skeleton banches. II. SKELETON GROWING WITH CONTOUR INFORMATION A. The Poposed Contou Samplng Method usng Dscete ISBN: IMECS 009

2 Poceedngs of the Intenatonal MultConfeence of Engnees and Compute Scentsts 009 Vol I IMECS 009 Mach Hong Kong Cuve Evoluton GHT [4] was ntally poposed to epesent a plana set D wth abtay bounday usng a so-called R-table [4]. As an example shown n Fg. the bounday of the plana set D can be descbed by geometc elatonshp between the centod X R of D and the bounday pont X s. Accodng to the R-table n GHT to epesent the bounday n queston can be constucted as: n ( (...( n α α α n ( (...( n α α α ( n ( (...( 3 n α3 3 α3 3 α3 n ( (...( 3 n 3 k k α k k αk k αk. whee s the common slope fo the tangent lne passng though the bounday ponts x j j =... n. Howeve the nfomaton of R-table n GHT cannot lnk nfomaton of bounday nto the plana set D n an mage and t s also dffcult to expess whch bounday s a sgnfcant vsual pat. The chaactes of sgnfcant vsual pat n a contou have be poposed n lteatue [5]. We can summaze the obsevaton nto fou ules: ( These vsual pats ae defned to be convex o nealy convex shape fom the est of object at concavty extema. ( Although the obsevaton that vsual pats ae nealy convex shapes s vey natual. The man poblem s to detemne the meanng of nealy n ths context. (3 Many sgnfcant vsual pats ae not convex n the mathematc sense snce a vsual pat may have small concavtes e.g. small concavtes caused by fnges of the human hand. (4 The ole of each vsual pat n any object s dffeent fom the sense of human vson e.g. the pependcula angle s less than the staght lne n a squae shape. If the pependcula angle s loss then t cannot fom a squae. On the opposte vew nceasng o deceasng the staght lnes wll stll mantan the squae. In ths espect the smalle numbe of vsual pats s moe sgnfcant than the lage numbe of vsual pats. To estmate the sgnfcant vsual pat n a whole object s a dffcult task wthout a po knowledge about the bounday of objects o wthout use nteactve. Ou soluton s usng a heachcal evoluton ule whch ncludes two stages: ( estmate the tunng pont of vsual pats based on the chan-code method and dscete cuve evoluton; ( select the vsual pat nto sgnfcant vsual pats fom all of vsual pats n an object. Fst we popose a contou mplng method fo estmatng the tunng pont of vsual pats based on chan-code method. In the chan-code pocess the pont coded moves along the dgtal cuve o edge pxels wth 8-adjacency model n 8-dect code. Ths assumes that the chan-code wth 8-adjacency n a 3 3 block s lmted to a multple of 45 0 and t s quantzed to be the neaest multple of A bounday chan stats wth a andom pont n the edge pxels. Each edge pxel has 8 neghbong ponts among whch thee s at least one edge pont. The bounday chan-code s the decton descpton of cuent pont a j to the next one a j+ and the chan-code can be defned as e j = a j a ( j + whee e j denotes the numbe 0 to 7 fo a descpton n 8-decton chan-code. y X R Fg..The coodnated elatonshp between a bounday pont X and the centod X R of an object wth abtay shape. e e + a j+ a j+ e e + e a j a j+ a j+ a j a j+ a j a j+ (a (b (c a j+ a j a j+ a j a j+ e + e e e j+ a j e a j+ a j+ a j+ (d (e (f a j a j+ e a j+ (g ej+ Fg. shows the possble 7 types of vsual pats n a 3 3 block. e + The bounday n a plana set D can be descbed wth a stat pont and a sees of sequence decton codes. Thee ae some poblems of chan-code method: ( the chan-code vaes damatcally wth dffeent stat ponts. Selectng the pope stat pont on the chan-code s a common pocess; ( the chan-code method cannot be appled to the otaton and scalng of D. Based on ths eason the consecutve pmtve edge s poposed to descbe the bounday of D. The concept of consecutve pmtve edge s as follows: = e e =... n (3 whee e and e - denote the consecutve pmtve edges espectvely. The detected of can be mapped to 7 types of vsual pats as shown n Fg.. Accodng to the key popety of dscete cuve evoluton a elevance measue k s gven by β ( e j e j + ( e j ( e j + k( e j e j + = ( e j + ( e j + (4 whee e j and e j+ s a pa of consecutve pmtve edges β ( e j e j+ s the tun angle at the common vetex of pmtve edge e j and e j+ and s the length functon nomalzed wth espect to total length of the polygonal cuve. The man popety of ths elevance measue s that the hghe the value of k(e j e j+ the lage the contbuton to the shape e j+ X α x ISBN: IMECS 009

3 Poceedngs of the Intenatonal MultConfeence of Engnees and Compute Scentsts 009 Vol I IMECS 009 Mach Hong Kong of the cuve of ac e j e j +. Based on tsfyng the ule (-3 mentoned above the tunng pont of vsual pat may appea as a (ed ccle n Fg. usng the elevance measue k. The next poblem s to fnd the sgnfcant vsual pat whch hdes n the bounday of an object. Mappng the consecutve pmtve edge to a vsual pat s to encode an object wth vsual pats block by block along the bounday pxels. Hence two gven object blocks fom along the edge pxel can be encoded and ndcate whch vsual pat s mapped and the font of vsual pat e j+ and the ea of vsual pat e j n Eq. (3 ae ovelappng. Wthout loss of genealty the hstogam of consecutve pmtve edge s used to descbe the bounday of objects n ths pape. Let CPE =... 7 denote the type of consecutve pmtve edges and N s the numbe of CPE n Fg.. The bounday of object BO wll be descbed by (5 BO = N k k 7 Fo the CPE the local sgnfcance of a bounday pont s usually only consdeed and the global nfomaton of shape n an object s dscaded. Assume that the aangement of N k n descendng ode ( N N N3... N7 assocates the me odeng to the CPE s CPE CPE... CPE7 (6 A ato s decded to eseve how much of the vsual pats can epesent the object as the sgnfcant vsual pats and the emande wll be gnoed. The ato ρ s defned by N p ρ N j j 7 whee p (p<7 denotes pecedng sequences n eq. (7. It s mpotant to detemne a good stop cteon of the ato selected. Howeve the ato ρ selected usually appeas n a vaety of applcaton-dependent cases. Accodng to the expemental esults t can peseve the peceptual appeaance suffcently fo object ecognton when the ato ρ s assgned as 0.. A skeleton smlaty measue s useful fo object-based eteval n mage databases should be accodng to ou pecepton. Ths basc popety leads to the followng equements: ( A skeleton smlaty measue shall pemt ecognton of peceptually smla objects that ae not mathematcally dentcal. ( It shall peseve sgnfcant vsual pats of objects. (3 It shall not depend on scale oentaton o poston of objects. (4 A skeleton smlaty measue s unvel n the sense that t allows us to dentfy o dstngush objects of abtay skeleton.e. no estctons on shapes ae assumed. We should futhe ntoduce the skeleton gowng based on followng ules. Rule. Let the bounday D of a set D be composed of k smple contou segments C C C k. Let T T T n be the tunng ponts lyng on the smple contou segment (7 whch wee selected usng Eq. (7. The tunng pont set T also geneated a skeleton banch. Rule. Besdes the tunng pont we should fnd the punng pont set P j fom the cuve of plane between the neghbos of two tunng ponts accodng to the aveage cuvatues. The punng pont s used to detemne the skeleton pont and not to bng on the skeleton banch. The centodυ of bounday featue space s defned as: N N ( x y = ( x y (8 N = N = whee x and y ae two-stmulus poston values of th vecto of bounday featue spaces. Assume that functon f denotes a cuve of a plane whch s composed of n ponts c c c n and a pont c at the functon f can be epesented as (x f(x shown as Fg. 3 the cuvatue of c s f ''( x Ω = (9 (+ f '( x 3 / the aveage of cuvatues s computed as Ω + Ω Ωn χ T = (0 Nn the punng pont should be found as Ω Ω + χ ( f c υ ( x y Fg. 3 shows the cuvatue Ω of a pont c at the functon f. Rule 3. If a staght bounday s between the neghbos of two tunng ponts then the punng pont s detemned usng the cente of the staght bounday. Rule 4. The skeleton should be gown accodng to the bounday ponts set R of the object whch nclude tunng ponts set T and punng ponts set P j and defned as R = {{ T } { Pj } =... n j =... m. Rule 5. Connect skeleton ponts whch ae found usng the bounday pont set R and tunng ponts T s the skeleton ac of the object s found. B. Skeleton Gowng Assume that a - a and a + denote two consecutve ponts and the a s a tunng pont whch belongs to the set of T. The bounday segments between a - and a and a and a + can be epesented as ax+by+c=0 and dx+ey+f=0 espectvely whee a b c d e and f denote the paametes of bounday segments. It should fnd the auxlay lne L whch connects pont a - and a + shown as Fg.4. Letθ denote an ncluded angle between the lne ax+by+c=0 and dx+ey+f =0. That s θ = θ θ ( Accodng to the tangent functon t can be found as T ISBN: IMECS 009

4 Poceedngs of the Intenatonal MultConfeence of Engnees and Compute Scentsts 009 Vol I IMECS 009 Mach Hong Kong tanθ = tan( θ θ tan θ + tan θ = tan θ tan θ Let x = tan θ t wll be computed as θ ( ad + be + ( bd ae x = tan = ( bd ae (3 (4 Accodng to the θ θ = θ + t s smple to pove tanθ tan θ θ tanθ = tan( θ = (5 + tanθ tan θ The staght lne L s found whch connected the tunng pont and skeleton pont as ( y y = tanθ ( x x (6 The staght lne L should ntesect anothe lne L n the object. Let the L defne as gx+hy+=0 (7 Fg. 4. A skeleton pont s s gown usng the tunng pont a. Combnng the equatons (6 and (7 t s assumed that the homogeneous system has a nontval soluton. The nontval soluton of system should be found by pefomng of Guass-Jodan educton pocedue on the augmented matx [M0]. The esult s 0 k 0 (8 0 k 0 whee k = ae the atos of x and y. Based on the educton esults the values of x and y has the ntesect pont between staght lne L and L and can be computed as (9 ( x y = ( k + k + k k + k + k The skeleton pont should be found as x ( + x y + y s = (0 Based on the skeleton pont sets sk k = n + m s found fom the bounday ponts set R of the object. The skeleton ac comes nto beng accodng to the followng algothm. Algothm : Poposed the skeleton ac of object comes nto beng. Input: Two bounday pont sets {T } and R = {{ T } { Pj } =... n j =... m Output: A skeleton ac of the object comes nto beng. Method:. Let S denote the collecton of all the skeleton pont sets s k and empty ntally.. Let E denote the completed skeleton ac of an object and empty ntally. 3. whle ( R NULL Fnd a skeleton pont usng a bounday pont n R by the equaton (0. Inset the skeleton pont nto S and delete the skeleton pont fomr. 4. Select a skeleton pont fom S to E. 5. Whle ( S NULL 5.. Fnd a skeleton pont p fom S and ts mnmum dstance s d mn ( p. q whee q s a skeleton pont n E. 5.. Inset the skeleton ac nto E and delete the skeleton fomr. 6. Whle ( T NULL 6.. Fnd a skeleton pont p fom T and ts mnmum dstance s d mn ( p. q whee q s a skeleton pont n E. 6.. Inset the skeleton banch nto E and delete the skeleton pont fom T. III. CONTOUR REPRESENTATION BASED ON TWO CONSECUTIVE PRIMITIVE EDGES In the compute vson thee s a long hstoy of wok on contou epesentaton and contou smlaty. Some well-known methods nclude Foue descpto moment nvaants wavelet descptos and hstogam of bounday dectos. Wthout loss of genealty the hstogam of CPE n Eq.(3 s used to descbe the contou epesentaton n ths pape. Fo pactcal puposes the hstogam of CPE method cannot effcently and coectly descbed the contou of an object. As shown n Fg. (c and (f the hstogam of CPE s the me because t s a dscete pmtve vsual patten. To solve ths poblem the Eq.(3 s modfed nto two consecutve pmtve edge (α Γ as follows: ( Γ α = j j + = e j e j e j + e j o ( Γ α = j + j = e j + e j e j e j ( whee denotes a unon opeaton. Instead of epesentng a bounday n any possble combnaton the detected two-consecutve pmtve edge (TCPE s mapped to 6 types of vsual patten as shown n Fg.5. The man eason fo mappng the TCPE to vtual-patten s to encode the bounday of an object wth vsual-patten block by block along the edge pxels. Hence two gven object blocks fom along the bounday pxel can be encoded and can ndcate whch vsual-patten s mapped. If we have a shape of an object such as Fg. the R-table can be modfed based on the poposed TCPE as α α α ( Γ ( a0 a a a3( Γ ( a a3 a4 a5...( Γ n ( an an + a0 a ( whee α s belongng to the type of vtual-patten n Fg. 5 a 0 and a n denote the stat-pont and end-pont espectvely. To obtan the consstency of TCPE fo any stuctue of objects two decson ules ae consdeed: ( the statng bounday and endng bounday ovelap; ( the scannng sequence uses the antclockwse method n the bounday of object. IV. SIMILARITY MEASUREMENT OF OBJECT ISBN: IMECS 009

5 Poceedngs of the Intenatonal MultConfeence of Engnees and Compute Scentsts 009 Vol I IMECS 009 Mach Hong Kong REPRESENTATION Consde a database DB consstng of a lage numbe of objects. Each of them s epesented as a hgh-dmensonal featue vecto F = { Γ Φ β} whee ΓΦ and β denote the featue vecto of TCPE skeleton acs and skeleton banch n an object espectvely. The featue vecto of TCPE can futhe be epesented as Γ = {{ f p } =...6; j... n} j = whee f and p j ae th featue and the coespondng numbe of TCPE n Fg. 6 espectvely. The total numbe of TCPE n an object can be computed as 6 ζ =. (3 p j = Fg.5. Possble sxteen types of vsual pattens n a squae block. Let X = {{ x pk} k =... 6} and Y = {{ y j qk} k =... 6} be the featue vectos of TCPE. Then the dstance between X and Y based on the concept of QBIC [6] can be computed as (4 DTCPD ( x y = p + q j a j pq j = j = = j= whee a j s the peceptual coeffcent between featue values p k and q k. The ole of each TCPE n any object s dffeent fom the sense of human vson. The fewe numbes of TCPE s moe mpotant than many numbes of TCPE n an object. Thus the peceptual coeffcent a j can be defned as + p q j (5 a j = = j= p q j whee the values p and q j ae assumed as non-zeo othewse the coespondng value of / p o / q j s assgned as zeo. The featue vecto of skeleton acs can futhe be epesented as β = {{ s s+ θ} =... n} shown as Fg. 6 whee s and s + ae the consecutve of skeleton acs and θ denotes the ncluded angle between the consecutve skeleton acs s and s +. A weght of skeleton acs n an object can be found as = n W W (6 = and the W s defned as θ W = (7 s + s+ Let a a a X = {{ s s+ θ } =... n} and b b b Y = {{ s j s j + θ j } j =... m be the featue vectos of skeleton acs. Then the dstance between X and Y s computed as D = W W (8 e 3 e b 5 e b b s s s 3 b 4 s 4 s 5 s 6 s 7 e 4 b6 e 6 b 3 X e 5 Y : Bounday of object :Punng pont decson :Skeleton acs :Skeleton Banch Fg. 6. An example of epesentng an object by the bounday of object skeleton acs and skeleton banch. The featue vecto of a skeleton banch can futhe be epesented as = {{ e ej bk } j =... m k =... n} shown as Fg. 6 whee b k denotes the skeleton banch and e and e j ae the bounday edges of object whch s connectng to the skeleton banch b k. A weght of a skeleton banch n an object can be found as = W W (9 = and the W s defned as s j when s > s s j = (30 W b k s when s j > s s j Let x x x X = {{ e e j bk } j =... m k =... n} and y y y Y = {{ e l em bn } l m =... m n =... n} be the descpton vectos of a skeleton banch. Then the dstance between X and Y s computed as D = WX WY (3 Note that the values of D TCPD D and D should be nomalzed by the maxmum values of D TCPD D and D espectvely befoe advancng to defne smlaty measuements between the two objects X and Y. Ths nomalzaton pocess wll esult n the nomalzed values of D TCPD D and D ae confned to be wthn the (0 nteval. Let D ~ TCPD D ~ and D ~ denote the nomalzed D TCPD D and D espectvely. The measuement of smlaty D s ( X Y between the two objects X and Y on the bass of skeleton ac and skeleton banch featues ae then defned as ~ ~ Ds ( X Y = ( α D + α D (3 whee α and α epesent the weghtng of D ~ and D ~ espectvely and α + α =. Note that the value of D s ( X Y ISBN: IMECS 009

6 Poceedngs of the Intenatonal MultConfeence of Engnees and Compute Scentsts 009 Vol I IMECS 009 Mach Hong Kong between 0 and. The lage the value of D s ( X Y mean a geate smlaty between the quey object X to the database object Y. Combnng the skeleton and contou featues the hybd smlaty measuement can be defned as ~ DTotal = β Ds ( X Y + β DTCPD (33 whee DTotal s the value of hybd smlaty D s ( X Y and D ~ TCPD ae the values of smlaty on the bass of skeleton and contou featues espectvely and β and β epesent the weghtng of D s ( X Y and D ~ TCPD espectvely. We should also set β + β =. V. EXPERIMENTAL RESULTS In ode to evaluate the poposed appoach a sees of expements wee conducted on an Intel PENTIUM-IV 3GHz PC. A skeletal measue method poposed by Tosello and Hancock s method [7] s also smulated by compute softwae fo the pupose of pefomance compason. An mage database whch conssted of 66 bnay objects s extacted fom sceney mages. Each object mage n database s fst fomatted to fo testng the eteval appoach. Befoe the evaluaton human assessment was done to detemne the elevant matches n the database to the quey object mage. The top 00 etevals fom both the Tosello and Hancock s method and the poposed appoaches wee maked to decde whethe they wee ndeed vsually smla n skeleton and contou. It s dffcult to deve a fomal method n evaluatng the eteval accuacy of an mage database system. Tadtonal metcs fo evaluatng pefomance ae ecall and pecson. They ae functons of both coect matches and the elevance of database mages to a quey. The eteval accuacy measued by ecall and pecson s computed as followng. Recall measues the ablty of the system to eteval all the mages that ae elevant and defned as Re levances coectly eteved Re call =. all elevances Pecson measues the ablty of the system to eteve only mages that ae elevant and can be computed by elevances coectly eteved P ecson =. all eteved Recall and pecson eque a gound tuth to assess the elevance of mages fo a set of sgnfcant quees. The pefomance of the poposed mage eteval method s evaluated n tems of eteval accuacy. The aveage pecson and ecall cuves ae plotted n Fgs. 7(a and 7(b espectvely. It can be seen that the poposed method acheves good esults n tems of eteval accuacy compaed wth Tosello and Hancock s method [7]. VI. CONCLUSION In ths pape we have pesented the ecognton of shape-matchng fo object eteval n mage databases usng skeleton and contou by dscete cuve evaluaton and two consecutve pmtve edges. Object segmentaton and ecognton s the pmay step of compute vson to acheve mage eteval of hgh-level mage analyss. Contou-based and skeleton-based epesentatons ae mpotant fo object ecognton n dffeent aeas. In ths pape we poposed a novel method to ntegate the contou-based appoaches wth skeleton-based appoaches fo object epesentaton. The contou-based and skeleton-based epesentatons ae based on the poposed two-consecutve pmtve edges method and dscete cuve evoluton method espectvely. The expemental esults demonstate that the poposed method s supeo to Tosello and Hancock s method n tems of eteval accuacy. REFERENCES []W. H. T. And S. S. Yu 985 Attbuted stng matchng wth megng fo shape ecognton IEEE Tans. PAMI 7(4 pp [] L. J. Lateck and R. Lakampe 999 Convexty Rule fo shape Decomposton Based on Dscete Contou Evoluton Compute Vson and Image Undestandng 73(3 pp [3] C. D. Rubeto 004 Recognton of shape by attbuted skeletal gaphs Patten Recognton 37 pp. -3. [4] S. C. Cheng C. T. Kuo and H. J. Chen 007 Vsual object eteval va block-based vsual-patten matchng Patten Recognton 40 pp [5] L. J. Lateck and R. Lakampe 999 Convexty Rule fo Shape Decomposton Based on Dscete Contou Evoluton Compute Vson and Image Undestandng 73 pp [6] M. flckne H. Sawhney W. Nblack J. Ashley Q. Huang B. Dom M. Gokan J. Hafne D. Lee D. Petkovc D. Steele and P. Yanke Quey by mage and vdeo content: the QBIC system IEEE Compute 8(9 pp [7] A. Tosello and E. R. Hancock 004 A Skeletal measue of D shape smlaty Compute Vson and Image Undestandng 95 pp. -9. n o s P ec l R eca Poposed method usng skeleton and contou featues Poposed method usng contou featues Poposed method usng skeleton featues Tosello and Hancock's Method Numbe of etevals (a Poposed method usng skeleton and contou featues Poposed method usng contou featues Poposed method usng skeleton featues Tosello and Hancock Method Numbe of etevals (b Fg.7. Aveage pecson and ecall vesus numbe of eteved mage: (a Pecson; (b Recall. ISBN: IMECS 009