chdong@npic.edu.tw rola@mail.stu.edu.tw (ITS) (LPR) ITS 2. [1][8] [3][9][12] [9] frequency table Sobel [3][12] RGB HSB color model [11] Hough transformation Sobel [4] [10] 1. Intelligent Transportation Systems, ITS 3. License Plate 3.1 Recognition, LPR ITS 1 A23456 A23458 (Template Matching) 5 0B6G A23450A2345BA23456A2345G 3 6 A23456
P(x,y) P(x-1,y) P(x,y-1) P(x,y+1) P(x+1,y) 1 3.2 Sobel LaplacePrewittRoberts Sobel [2] Sobel 3.3 2 [6] 0 1 1: P(x,y) t (4-connectivity) 2: P(x,y) t 3: P(x,y) 4: t P(x,y) t P(x,y) ( ) 3
1objHEIGHT objheight_base_threshold 2objWIDTH > objwidth_base_threshold 3min_AR_thd < obj_aspect_ration < max_ar_thd 3.4 objheight objwidth 4 obj_aspect_ration / 5 threshold 1 2 3 6 4 7 6 3 6 ( 7 ) 3.4.2 5 4 ( 8 ) [5] 3.4.1
4 1 1 ; 0 12 8 3.4.3 11 9 12 12 min_dns_thd < obj_density < max_dns_thd obj_density / 3.4.5 9 y 13 ( 1 4 ) ( ) y threshold ( 0 0 ) [7] 1 y y y_point_thd 2 10 td_height_thd 3.4.4 11 11
2 13 1 y 1 y ( ) L y y_point_thd 1 y 14 14 3.5 36 20 (Template Matching) (Template) R 2 X X k T (3.5.1) 2 2 (X -X) (T -T k ) R = k i i j j ij ij ijk ((X -X) )((T -T )) 2 2 ijk k ( 3.5.1) k 1 k
Xij i j Tijk k i j X Tk X ij T ijk / /k R 1-1 0 1 X 16 0D8 B T X T k R R T 0Q X 180 X 3.5.1 0 6 Q 3.5.2 5 Right_R 36 Plate_width( 17) Plate_width ( 18(a)) R 15(a) Plate_width ( 18(b)) Right_Left_R 2*36 15(b) 17 Plate_width 15 E F P1*36 Right_R 15(a) (3.5.1) X T 1*36 18 R T 3.4.5 Std_w 9 5 Right_Left_R 15(b) IF 5.1 Plate_width /Std_w 6.1 (3.5.1) R Plate_width T Plate_width Std_w 0D 8B 18(b) [2] ELSEIF 6.1 Plate_width /Std_w 7.1
Plate_width 3 (216 ) Plate_width 18(a) 1 1296 1284 12 1% 99.0% END Plate_width 2 1296 1290 6 0.4% 99.6% 2 3 1 4 2 4 1 k R R R_thd 4. 4.1 5 2 67% 67% 3 0% 67% 4 0% 67% CANON 5 8% 75% PowerShot A70320 6~12 25% 100% 640*480 12 0% 100% Microsoft Windwos XP SP1 AMD Athlon(tm) XP 1800+ 75 512 MB 5 MATLAB 6.5(sp1) 5 4.2 4.3 1 223 6 216 5 A23456 6 1 2 A23458 6 5 0B6 6 G A23450A2345B A23456A2345G 3 6 6 A23456 6 223 19 204 1 216 206 10 5% 95% 1000 2 216 6 6 216 3 1 2 212 4 2% 98%
7 6 [7] Shih-Hao Yu, Jun-Wei Hsieh and Yung-Sheng 1 223 206 17 8% 92% 2 223 212 11 5% 95% License Plates of Motorcycles on Highways, National Chiao Tung University, Hsinchu, 2000. [9] Ter Brugge M.H., Stevens J.H., Nijhuis J.A.G., Spaanenburg L., License plate recognition using DTCNNs, 1998 Fifth IEEE International Workshop on Cellular Neural Networks and Their Applications Proceedings, pp. 212-217, 1998. [1] Chang Jen-Hao, Vehicle License Plate Recognition Using Orthogonal Projection and Tree Decisions, National Tsing Hua University, Hsinchu, 2001. [2] Chen-Hsing Wang, A Multi-target Vehicle License Plate Recognition System, Yuan Ze University, Taoyuan, 2003. [3] Li-Shien Chen, Localization and Recognition of Vehicle License Plates, National Taiwan Normal University, TaiPei, 2002. [4] Lin,Tai-Liang, Intelligent License Plate Searching and Content Segmentation in Image Processing, National Taiwan University, Taipei 2000. [5] J.A.G. Nijhuis, M.H. ter Brugge, K.A. Helmholt, J.P.W.Pluim, L. Spaanenburg, R.S. Venema, M.A. Westenberg, Car License Plate Recognition with Neural Networks and Fuzzy Logic, University of Groningen, Department of Computing Science, Netherlands, 1995. [6] R.C. Gonzalez, R. E. Woods, Digital Image Processing, Prentice Hall, 2001. Chen, Morphology-based License Plate Detection from Complex Scenes, IEEE Proc. of International Conference on Pattern Recognition, Québec City Convention Center, Canada, (August 11-15, 2002), Vol. III, 176-179, 2002. [8] Si-Yuan Chen, Extraction and recognition of [10] Y. Lu, On the Segmentation of Touching Characters, Document Analysis and Recognition, 1993., Proceedings of the Second International Conference on, 1993, Page(s): 440-443 [11] Yungang Zhang, A New Algorithm for Character Segmentation of License Plate, IEEE Transactions on Pattern Analysis conference, 2003. [12] Zhu Wei-gang adn Hou Gou-jiang, A study of Locating Vehicle License Plate Based on Color Feature and Mathematical Morpholoygy, IEEE Conference on ICSP, vol.2 pp.748-751, 2002.
Click below to find more Mipaper at www.lcis.com.tw Mipaper at www.lcis.com.tw