基于独立边数的链码方法
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摘要
提出一种适用于表达不同类型边界网格的链码方法.该链码可通过记录各边界网格的独立边数得到,称之为边链码.其中,六边形网格边链码即各边界网格的独立边数集合;四边形网格的边链码在记录独立边数的同时,可区分2种不同轮廓行进方向;三角形网格的边链码则由"0"~"3"和"4"~"7"分别表示独立边数为1或2时的4种情况;对于边界上的特殊情况,边链码分别利用无意义的编码组合对原码值进行替换,有效减少编码冗余.边链码与起始位置无关,具有旋转与翻转不变性,并能够检测直线段以及计算边界周长.将边链码与4种经典的链码方法进行编码效率对比实验,结果表明,边链码能够应用于各类网格边界表达,六边形与三角形的边链码总码数分别为VCC的50%和78%左右,四边形边链码的压缩率可达0.827 5.
A new chain code applied to various types of boundary grids was proposed. This chain code relied on counting the independent edge number of each boundary grid, called Edge Chain Code(ECC). ECC for hexagonal grids was exactly the independent edge number sequence. ECC for rectangular grids could be obtained by recording the independent edge numbers of each boundary grid and distinguishing two different contour moving directions with "0". ECC for triangular grids used "0"~"3" and "4"~"7" to express four conditions with edge number of 1 or 2 separately. Moreover, among all these chain codes, meaningless combinations were used to express the special cases and reduce the coding redundancy. ECC was invariant to start point, rotation and mirroring, which could also detect straight line segments and count boundary perimeter. Finally, ECC was compared with four classical chain codes on encoding efficiencies and storage memories. Results show that ECC can be applied to express all kinds of grid boundaries, the total coding numbers of ECC for hexagonal grids and triangular grids are separately 50% and 78% of VCC, and the compression ratio of ECC for rectangular grids can reach 0.827 5.
A new chain code applied to various types of boundary grids was proposed. This chain code relied on counting the independent edge number of each boundary grid, called Edge Chain Code(ECC). ECC for hexagonal grids was exactly the independent edge number sequence. ECC for rectangular grids could be obtained by recording the independent edge numbers of each boundary grid and distinguishing two different contour moving directions with "0". ECC for triangular grids used "0"~"3" and "4"~"7" to express four conditions with edge number of 1 or 2 separately. Moreover, among all these chain codes, meaningless combinations were used to express the special cases and reduce the coding redundancy. ECC was invariant to start point, rotation and mirroring, which could also detect straight line segments and count boundary perimeter. Finally, ECC was compared with four classical chain codes on encoding efficiencies and storage memories. Results show that ECC can be applied to express all kinds of grid boundaries, the total coding numbers of ECC for hexagonal grids and triangular grids are separately 50% and 78% of VCC, and the compression ratio of ECC for rectangular grids can reach 0.827 5.
引文
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[2]RACHMAWATI E,IPING S,MASAYU L K.Bagof-shapes descriptor using shape association based on freeman chain code[J].Journal of Theoretical and Applied Information Technology,2017,95(5):1142-1153.
[3]LEE D,KIM S J.Modified chain-code-based object recognition[J].Electronics Letters,2015,51(24):1996-1997.
[4]KARCZMAREK P,KIERSZTYN A,PEDRYCZ W,et al.An application of chain code-based local descriptor and its extension to face recognition[J].Pattern Recognition,2017,65:26-34.
[5]YUHANDRI,MADENDA S,PRASETYO E.Object feature extraction of songket image using chain code algorithm[J].International Journal on Advanced Science,Engineering and Information Technology,2017,7(1):235-241.
[6]TAWFIQ A,ASADI A,JODA F A.Removing spatial redundancy from image by using variable vertex chain code[J].European Academic Research,2014,2(1):179-192.
[7]REN M,KARIMI H A.A chain-code-based map matching algorithm for wheelchair navigation,Trans[J].Transactions in GIS,2009,13(2):197-214.
[8]FREEMAN H.On the encoding of arbitrary geometric configurations[J].IRE Transactions on Electronic Computers,1961,10(2):260-268.
[9]BRIBIESCA E.A new chain code[J].Pattern Recognition,1999,32:235-251.
[10]SANCHEZ H C,DAGNINO R M.Compressing bilevel images by means of a 3-bit chain code[J].SPIE Optical Eng,2005,44(9):1-8.
[11]SANCHEZ H C,BRIBIESCA E,DAGNINO R M.Efficiency of chain codes to represent binary objects[J].Pattern Recognition,2007,40(6):1660-1674.
[12]BORUT Z,MONGUS D,LIU Y K,et al.Unsigned Manhattan chain code[J].Journal of Visual Communication and Image Representation,2016,38:186-194.
[13]LIU Y K,ZALIK B.An efficient chain code with Huffman coding[J].Pattern Recognition,2005,38(4):553-557.
[14]CRUZ H S.Proposing a new code by considering pieces of discrete straight lines in contour shapes[J].Journal of Visual Communication and Image Representation,2010,21(4):311-324.
[15]ZALIK B,MONGUS D,ZALIK K R et al.Chain code compression using string transformation techniques[J].Digital Signal Processing,2016,53(6):1-10.