Abstract: In order to overcome the shortcomings of existing parallel thinning algorithms,such as thinning incompletely and 2-pixels slash thinning distortion,an improved thinning algorithm is proposed.A set of reservation templates and elimination templates for binary image were constructed firstly.The elementary thinning process was performed by arithmetic and logic operation,while 2-pixels slash was reserved by reservation templates matching.Then the redundancy pixels on slash were deleted by elimination templates matching,and the 8-connected single-pixel image was acquired.Experimental results on character images show that,the proposed algorithm could effectively avoid the 2-pixels slash thinning distortion,maintain the topological structure of original image,and achieve complete thinning result.