K3M: A universal algorithm for image skeletonization and a review of thinning techniques <s> Algorithm description. <s> The authors review their pseudo-one-subcycle parallel thinning algorithm. They present two improved versions of this algorithm, and describe a two-stage structure to realize the one-subcycle parallel algorithm. The first stage is to produce a perfect 8-curve excluding T-junction thin line. The second is to obtain the isotropic skeleton of an L-shaped pattern. The two stage structure consists of a thinning table and a control unit. The thinning table is used to provide the attributions for an input 3*3 local pattern. The control unit is used to check the removal of the center pixel of this local pattern, and the inputs of the control unit also comprise the outputs of other neighboring thinning tables. This structure can exactly implement the proposed one-subcycle parallel algorithms. The two improved algorithms have been implemented. Experiments confirm that the improved algorithms can produce the desired effective thin line and also show that the structure realized is feasible and practicable. > <s> BIB001 </s> K3M: A universal algorithm for image skeletonization and a review of thinning techniques <s> Algorithm description. <s> Abstract This paper describes a systematic approach for designing parallel thinning algorithms, in which three new functions, named local connecting, extended local connecting and erosive direction number, are introduced. With these functions as well as two properties of shape invariance of local edges and local straight lines, all the possible cases of 2-subcycle parallel thinning algorithm are constructed and all the corresponding removing conditions are generated and assigned automatically. In addition, the pseudo 1-subcycle parallel thinning algorithm is also presented. Finally, the effects and efficiency of the above proposed algorithms are analyzed and compared with those of some presently well-known algorithms. Experimental results confirm this new approach, and an efficient and effective algorithm has been built for practical applications. <s> BIB002 </s> K3M: A universal algorithm for image skeletonization and a review of thinning techniques <s> Algorithm description. <s> Many algorithms for vectorization by thinning have been devised and applied to a great variety of pictures and drawings for data compression, pattern recognition and raster-to-vector conversion. But parallel thinning algorithms which generate one-pixel-wide skeletons can have difficulty preserving the connectivity of an image. In this paper, we propose a 2-subiteration parallel thinning algorithm with template matching (PTA2T) which preserves image connectivity, produces thinner results, maintains very fast speed and generates one-pixel-wide skeletons. <s> BIB003 </s> K3M: A universal algorithm for image skeletonization and a review of thinning techniques <s> Algorithm description. <s> The authors propose a thinning algorithm based on clustering the image data. They employ the ART2 network which is a self-organizing neural network for the clustering of Arabic characters. The skeleton is generated by plotting the cluster centers and connecting adjacent clusters by straight lines. This algorithm produces skeletons which are superior to the outputs of the conventional algorithms. It achieves a higher data-reduction efficiency and much simpler skeletons with less noise spurs. Moreover, to make the algorithm appropriate for real-time applications, an optimization technique is developed to reduce the time complexity of the algorithm. The developed algorithm is not limited to Arabic characters, and it can also be used to skeletonize characters of other languages. <s> BIB004
K3M consists of an iterative part of seven phases and a single additional phase at the end, which is responsible for producing a one pixelwidth skeleton. The overview of the algorithm is presented in Fig. 17 .  iterative, 2-subcycles does not give a one-pixel-wide skeleton 1989 BIB001 BIB002 1-subcycle, parallel bias-reduced skeletons 1994  force-based acquires a skeleton by using force vectors 1996 BIB003 2-subcycles, parallel preserves connectivity, produces one-pixel-wide skeletons 1998 BIB004 