Zhang-Suen细化算法的实现没有达到预期效果

Question

我正在尝试使用Zhang-Suen thinning algorithm。我已经尝试在Java中实现它。但问题是它能找到边缘，而不是一条像素宽度的线。我第一次使用这个算法，我不知道我的逻辑出了什么问题。

我想要实现的是：

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我能够做到的是：

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 public void thinStepI(){

     delList.clear();
    neighbor = 0;
    connectivity = 0;

     for(int i=4;i<width-4;i++)
        for(int j=4;j<height-4;j++){
            p = pixelList[i][j];
            if (p == 1){
                p1 = pixelList[i-1][j]; 
                p2 = pixelList[i-1][j+1]; 
                p3 = pixelList[i][j+1]; 
                p4 = pixelList[i+1][j+1]; 
                p5 = pixelList[i+1][j];
                p6 = pixelList[i+1][j-1]; 
                p7 = pixelList[i][j-1]; 
                p8 = pixelList[i-1][j-1];  


                neighbor = p1 + p2 + p3 + p4 + p5 + p6 + p7 + p8;

                if (p1 == 0 && p2 == 1)
                    connectivity ++;
                if (p2 == 0 && p3 == 1)
                    connectivity ++;
                if (p3 == 0 && p4 == 1)
                    connectivity ++;
                if (p4 == 0 && p5 == 1)
                    connectivity ++;
                if (p5 == 0 && p6 == 1)
                    connectivity ++;
                if (p6 == 0 && p7 == 1)
                    connectivity ++;
                if (p7 == 0 && p8 == 1)
                    connectivity ++;
                if (p8 == 0 && p1 == 1)
                    connectivity ++;

                if ( connectivity == 1 && (neighbor >= 2 && neighbor <= 6) &&
                     (p1 * p3 * p5 == 0) && (p3 * p5 * p7 == 0) ){
                    delList.add(i);
                    delList.add(j);
                }



            }      
        }

     int length = delList.size();
     if (length != 0){
        for(int i =0; i < (length - 1); i+=2){
            pixelList[delList.get(i)][delList.get(i+1)] = 0;
            System.out.println("oldu");
        }
        thinStepI();
     }


}

   public void thinStepII(){
    delList.clear();
    neighbor = 0;
    connectivity = 0;

     for(int i=4;i<width-4;i++)
        for(int j=4;j<height-4;j++){
            if (pixelList[i][j] == 1){
                p  = pixelList[i][j]; // ** Origin Pixel ** 
                p1 = pixelList[i-1][j]; 
                p2 = pixelList[i-1][j+1]; 
                p3 = pixelList[i][j+1]; 
                p4 = pixelList[i+1][j+1]; 
                p5 = pixelList[i+1][j];
                p6 = pixelList[i+1][j-1]; 
                p7 = pixelList[i][j-1]; 
                p8 = pixelList[i-1][j-1];                    

                neighbor = p1 + p2 + p3 + p4 + p5 + p6 + p7 + p8;

                if (p1 == 0 && p2 == 1)
                    connectivity ++;
                if (p2 == 0 && p3 == 1)
                    connectivity ++;
                if (p3 == 0 && p4 == 1)
                    connectivity ++;
                if (p4 == 0 && p5 == 1)
                    connectivity ++;
                if (p5 == 0 && p6 == 1)
                    connectivity ++;
                if (p6 == 0 && p7 == 1)
                    connectivity ++;
                if (p7 == 0 && p8 == 1)
                    connectivity ++;
                if (p8 == 0 && p1 == 1)
                    connectivity ++;

                if ( connectivity == 1 && (neighbor >= 2 && neighbor <= 6) &&
                     (p1 * p3 * p7 == 0) && (p1 * p5 * p7 == 0) ){
                    delList.add(i);
                    delList.add(j);
                }



            }     
        }

     int length = delList.size();
     if (length != 0){
        for(int i =0; i < (length - 1); i+=2){
            pixelList[delList.get(i)][delList.get(i+1)] = 0;
            System.out.println("oldu2");
        }
        thinStepII();
     }

}

导致我得到不正确结果的逻辑中的错误在哪里？

Answer 1

我认为你用来描述ZS算法的链接是错误的。删除前景像素的一个必要条件是它的交叉数是1。“交叉数”是指当你按顺时针顺序遍历8个相邻像素时，前景像素变为背景像素的次数。您的链接中的描述中似乎缺少这一点。请参阅：http://www.uel.br/pessoal/josealexandre/stuff/thinning/ftp/lam-lee-survey.pdf了解更好的讨论。

Answer 2

这句话

connectivity = 0;

应该放在每个方法中的两个for循环中。

Answer 3

您必须循环，直到位图没有剩余的更改。你只做了一次算法的迭代。