图像细化 A fast parallel algorithm for thinning digital patterns

我这是测试了两个人的代码,似乎有些区别的,第二篇作者贴出来的代码还存在一些bug,我简单修改了一下,实现的效果上似乎是有一下差别,后续看看论文再做评价。

两个方法也都能满足一定的需求。

参考blog:

https://blog.csdn.net/qianchenglenger/article/details/19332011 

https://blog.csdn.net/qq826309057/article/details/73008608

--------------------以下文字是第一篇的转载内容,代码我简单的测试demo--------------------------

  在我们进行图像处理的时候,有可能需要对图像进行细化,提取出图像的骨架信息,进行更加有效的分析。

     图像细化(Image Thinning),一般指二值图像的骨架化(Image Skeletonization) 的一种操作运算。

     所谓的细化就是经过一层层的剥离,从原来的图中去掉一些点,但仍要保持原来的形状,直到得到图像的骨架。骨架,可以理解为图象的中轴。

     好的细化算法一定要满足:

  • 收敛性;
  • 保证细化后细线的连通性;
  • 保持原图的基本形状;
  • 减少笔画相交处的畸变;
  • 细化结果是原图像的中心线;
  • 细化的快速性和迭代次数少;

    这里,我们对“Zhang并行快速细化算法”进行了实现(注意,该算法为并行算法,而我们在实现过程中并没有并行化处理,所以,效率并没有达到最好)。

    参考资料

细化算法
论文 A fast parallel algorithm for thinning digital patterns
 

// ThinImageDemo.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"


#include <opencv2/opencv.hpp>
#include <opencv2/core/core.hpp>
#include <iostream>
#include <vector>
using namespace cv;
 
void zhangSkeleton(Mat &srcimage);
 
/**
 * @brief 对输入图像进行细化
 * @param src为输入图像,用cvThreshold函数处理过的8位灰度图像格式,元素中只有0与1,1代表有元素,0代表为空白
 * @param maxIterations限制迭代次数,如果不进行限制,默认为-1,代表不限制迭代次数,直到获得最终结果
 * @return 为对src细化后的输出图像,格式与src格式相同,元素中只有0与1,1代表有元素,0代表为空白
 */
cv::Mat thinImage(const cv::Mat & src, const int maxIterations = -1)
{
    assert(src.type() == CV_8UC1);
    cv::Mat dst;
    int width  = src.cols;
    int height = src.rows;
    src.copyTo(dst);
    int count = 0;  //记录迭代次数
    while (true)
    {
        count++;
        if (maxIterations != -1 && count > maxIterations) //限制次数并且迭代次数到达
            break;
        std::vector<uchar *> mFlag; //用于标记需要删除的点
        //对点标记
        for (int i = 0; i < height ;++i)
        {
            uchar * p = dst.ptr<uchar>(i);
            for (int j = 0; j < width; ++j)
            {
                //如果满足四个条件,进行标记
                //  p9 p2 p3
                //  p8 p1 p4
                //  p7 p6 p5
                uchar p1 = p[j];
                if (p1 != 1) continue;
                uchar p4 = (j == width - 1) ? 0 : *(p + j + 1);
                uchar p8 = (j == 0) ? 0 : *(p + j - 1);
                uchar p2 = (i == 0) ? 0 : *(p - dst.step + j);
                uchar p3 = (i == 0 || j == width - 1) ? 0 : *(p - dst.step + j + 1);
                uchar p9 = (i == 0 || j == 0) ? 0 : *(p - dst.step + j - 1);
                uchar p6 = (i == height - 1) ? 0 : *(p + dst.step + j);
                uchar p5 = (i == height - 1 || j == width - 1) ? 0 : *(p + dst.step + j + 1);
                uchar p7 = (i == height - 1 || j == 0) ? 0 : *(p + dst.step + j - 1);
                if ((p2 + p3 + p4 + p5 + p6 + p7 + p8 + p9) >= 2 && (p2 + p3 + p4 + p5 + p6 + p7 + p8 + p9) <= 6)
                {
                    int ap = 0;
                    if (p2 == 0 && p3 == 1) ++ap;
                    if (p3 == 0 && p4 == 1) ++ap;
                    if (p4 == 0 && p5 == 1) ++ap;
                    if (p5 == 0 && p6 == 1) ++ap;
                    if (p6 == 0 && p7 == 1) ++ap;
                    if (p7 == 0 && p8 == 1) ++ap;
                    if (p8 == 0 && p9 == 1) ++ap;
                    if (p9 == 0 && p2 == 1) ++ap;
 
                    if (ap == 1 && p2 * p4 * p6 == 0 && p4 * p6 * p8 == 0)
                    {
                        //标记
                        mFlag.push_back(p+j);
                    }
                }
            }
        }
 
        //将标记的点删除
        for (std::vector<uchar *>::iterator i = mFlag.begin(); i != mFlag.end(); ++i)
        {
            **i = 0;
        }
 
        //直到没有点满足,算法结束
        if (mFlag.empty())
        {
            break;
        }
        else
        {
            mFlag.clear();//将mFlag清空
        }
 
        //对点标记
        for (int i = 0; i < height; ++i)
        {
            uchar * p = dst.ptr<uchar>(i);
            for (int j = 0; j < width; ++j)
            {
                //如果满足四个条件,进行标记
                //  p9 p2 p3
                //  p8 p1 p4
                //  p7 p6 p5
                uchar p1 = p[j];
                if (p1 != 1) continue;
                uchar p4 = (j == width - 1) ? 0 : *(p + j + 1);
                uchar p8 = (j == 0) ? 0 : *(p + j - 1);
                uchar p2 = (i == 0) ? 0 : *(p - dst.step + j);
                uchar p3 = (i == 0 || j == width - 1) ? 0 : *(p - dst.step + j + 1);
                uchar p9 = (i == 0 || j == 0) ? 0 : *(p - dst.step + j - 1);
                uchar p6 = (i == height - 1) ? 0 : *(p + dst.step + j);
                uchar p5 = (i == height - 1 || j == width - 1) ? 0 : *(p + dst.step + j + 1);
                uchar p7 = (i == height - 1 || j == 0) ? 0 : *(p + dst.step + j - 1);
 
                if ((p2 + p3 + p4 + p5 + p6 + p7 + p8 + p9) >= 2 && (p2 + p3 + p4 + p5 + p6 + p7 + p8 + p9) <= 6)
                {
                    int ap = 0;
                    if (p2 == 0 && p3 == 1) ++ap;
                    if (p3 == 0 && p4 == 1) ++ap;
                    if (p4 == 0 && p5 == 1) ++ap;
                    if (p5 == 0 && p6 == 1) ++ap;
                    if (p6 == 0 && p7 == 1) ++ap;
                    if (p7 == 0 && p8 == 1) ++ap;
                    if (p8 == 0 && p9 == 1) ++ap;
                    if (p9 == 0 && p2 == 1) ++ap;
 
                    if (ap == 1 && p2 * p4 * p8 == 0 && p2 * p6 * p8 == 0)
                    {
                        //标记
                        mFlag.push_back(p+j);
                    }
                }
            }
        }
 
        //将标记的点删除
        for (std::vector<uchar *>::iterator i = mFlag.begin(); i != mFlag.end(); ++i)
        {
            **i = 0;
        }
 
        //直到没有点满足,算法结束
        if (mFlag.empty())
        {
            break;
        }
        else
        {
            mFlag.clear();//将mFlag清空
        }
    }
    return dst;
}
 
 
int main(int argc, char*argv[])
{
    //获取图像
    //if (argc != 2)
    //{
    //    std::cout << "参数个数错误!" << std::endl;
    //    return -1;
    //}
	cv::Mat src = cv::imread("1.jpg", cv::IMREAD_GRAYSCALE);
    //cv::Mat src = cv::imread(argv[1], cv::IMREAD_GRAYSCALE);
    if (src.empty())
    {
        std::cout << "读取文件失败!" << std::endl;
        return -1;
    }
 
    //将原图像转换为二值图像
    //cv::threshold(src, src, 200, 1, cv::THRESH_BINARY);
	cv::threshold(src, src, 200, 255, cv::THRESH_BINARY);
    //图像细化
    //cv::Mat dst = thinImage(src);
	zhangSkeleton(src);
	cv::Mat dst = src;
    //显示图像
    //dst = dst * 255;
    cv::namedWindow("src1", CV_WINDOW_AUTOSIZE);
    cv::namedWindow("dst1", CV_WINDOW_AUTOSIZE);
    cv::imshow("src1", src);
    cv::imshow("dst1", dst);
	cv::imwrite("dst.jpg", dst);
    cv::waitKey(0);
}

void zhangSkeleton(Mat &srcimage)
{
	int kernel[9];
	int nl = srcimage.rows;
	int nc = srcimage.cols;
	vector<Point> delete_list;
	int A, B;
	while (true)
	{
		for (int j = 1; j < nl - 2; j++)
		{
			uchar* data_pre = srcimage.ptr<uchar>(j - 1);
			uchar* data = srcimage.ptr<uchar>(j);
			uchar* data_next = srcimage.ptr<uchar>(j + 1);
			for (int i = 1; i < (nc - 2); i++)
			{
				if (data[i] == 255)
				{
					kernel[0] = 1;
					if (data_pre[i] == 255) kernel[1] = 1;
					else  kernel[1] = 0;
					if (data_pre[i + 1] == 255) kernel[2] = 1;
					else  kernel[2] = 0;
					if (data[i + 1] == 255) kernel[3] = 1;
					else  kernel[3] = 0;
					if (data_next[i + 1] == 255) kernel[4] = 1;
					else  kernel[4] = 0;
					if (data_next[i] == 255) kernel[5] = 1;
					else  kernel[5] = 0;
					if (data_next[i - 1] == 255) kernel[6] = 1;
					else  kernel[6] = 0;
					if (data[i - 1] == 255) kernel[7] = 1;
					else  kernel[7] = 0;
					if (data_pre[i - 1] == 255) kernel[8] = 1;
					else  kernel[8] = 0;

					B=0;
					for (int k = 1; k < 9; k++)
					{
						B = B + kernel[k];
					}
					if ((B >= 2) && (B <= 6))
					{
						A = 0;
						if (!kernel[1] && kernel[2]) A++;
						if (!kernel[2] && kernel[3]) A++;
						if (!kernel[3] && kernel[4]) A++;
						if (!kernel[4] && kernel[5]) A++;
						if (!kernel[5] && kernel[6]) A++;
						if (!kernel[6] && kernel[7]) A++;
						if (!kernel[7] && kernel[8]) A++;
						if (!kernel[8] && kernel[1]) A++;
						//
						if (A == 1)
						{
							if ((kernel[1] * kernel[3] * kernel[5] == 0) 
								&& (kernel[3] * kernel[5] * kernel[7] == 0))
							{
								delete_list.push_back(Point(i, j));
							}
						}
					}               
				}
			}
		}
		int size = delete_list.size();
		if (size == 0)
		{
			break;
		}
		for (int n = 0; n < size; n++)
		{
			Point tem;
			tem = delete_list[n];
			uchar* data = srcimage.ptr<uchar>(tem.y);
			data[tem.x] = 0;
		}
		delete_list.clear();
		for (int j = 1; j < nl - 2; j++)
		{
			uchar* data_pre = srcimage.ptr<uchar>(j - 1);
			uchar* data = srcimage.ptr<uchar>(j);
			uchar* data_next = srcimage.ptr<uchar>(j + 1);
			for (int i = 1; i < (nc - 2); i++)
			{
				if (data[i] == 255)
				{
					kernel[0] = 1;
					if (data_pre[i] == 255) kernel[1] = 1;
					else  kernel[1] = 0;
					if (data_pre[i + 1] == 255) kernel[2] = 1;
					else  kernel[2] = 0;
					if (data[i + 1] == 255) kernel[3] = 1;
					else  kernel[3] = 0;
					if (data_next[i + 1] == 255) kernel[4] = 1;
					else  kernel[4] = 0;
					if (data_next[i] == 255) kernel[5] = 1;
					else  kernel[5] = 0;
					if (data_next[i - 1] == 255) kernel[6] = 1;
					else  kernel[6] = 0;
					if (data[i - 1] == 255) kernel[7] = 1;
					else  kernel[7] = 0;
					if (data_pre[i - 1] == 255) kernel[8] = 1;
					else  kernel[8] = 0;

					B = 0;
					for (int k = 1; k < 9; k++)
					{
						B = B + kernel[k];
					}
					if ((B >= 2) && (B <= 6))
					{
						A = 0;
						if (!kernel[1] && kernel[2]) A++;
						if (!kernel[2] && kernel[3]) A++;
						if (!kernel[3] && kernel[4]) A++;
						if (!kernel[4] && kernel[5]) A++;
						if (!kernel[5] && kernel[6]) A++;
						if (!kernel[6] && kernel[7]) A++;
						if (!kernel[7] && kernel[8]) A++;
						if (!kernel[8] && kernel[1]) A++;
						//
						if (A == 1)
						{
							if ((kernel[1] * kernel[3] * kernel[7] == 0) 
								&& (kernel[1] * kernel[5] * kernel[7] == 0))
							{
								delete_list.push_back(Point(i, j));
							}
						}
					}
				}
			}
		}
		size = delete_list.size();
		if (size == 0)
		{
			break;
		}
		for (int n = 0; n < size; n++)
		{
			Point tem;
			tem = delete_list[n];
			if (tem.y > srcimage.rows-1 || tem.x > srcimage.cols-1)
				continue;

			uchar* data = srcimage.ptr<uchar>(tem.y);
			data[tem.x] = 0;
		}
		delete_list.clear();
	}
}

运行效果

1原图像

2.运行效果

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转载自blog.csdn.net/liangchunjiang/article/details/81450498
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