opencv / javacv：如何迭代轮廓进行形状识别？ [英] opencv/javacv: How to iterate over contours for shape identification?

问题描述

我正在使用JavaCV开发一个形状识别项目，我发现了一些OpenCV代码来识别特定图像中的U形状。我试图将其转换为JavaCV，但它没有提供相同的输出。能帮我转一下这个OpenCV代码到JavaCV吗？

I'm developing a shape identification project using JavaCV and I have found some OpenCV code to identify U shapes in a particular image. I have tried to convert it into JavaCV but it doesn't give the same output. Can you please help me to convert this OpenCV code into JavaCV?

这是OpenCV代码：

This is the OpenCV code:

import cv2
import numpy as np

img = cv2.imread('sofud.jpg')
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
ret,thresh = cv2.threshold(gray,127,255,1)
contours,hierarchy = cv2.findContours(thresh,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)

for cnt in contours:
    x,y,w,h = cv2.boundingRect(cnt)
    if 10 < w/float(h) or w/float(h) < 0.1:
        cv2.rectangle(img,(x,y),(x+w,y+h),(0,0,255),2)

cv2.imshow('res',img)
cv2.waitKey(0)
cv2.destroyAllWindows()

这是预期的输出

这是转换后的代码：

import com.googlecode.javacpp.Loader;
import com.googlecode.javacv.CanvasFrame;
import static com.googlecode.javacpp.Loader.*;
import static com.googlecode.javacv.cpp.opencv_core.*;
import static com.googlecode.javacv.cpp.opencv_imgproc.*;
import static com.googlecode.javacv.cpp.opencv_highgui.*;
import java.io.File;
import javax.swing.JFileChooser;

public class TestBeam {
    public static void main(String[] args) {
        CvMemStorage storage=CvMemStorage.create();
        CvSeq squares = new CvContour();
        squares = cvCreateSeq(0, sizeof(CvContour.class), sizeof(CvSeq.class), storage);
        JFileChooser f=new JFileChooser();
        int result=f.showOpenDialog(f);//show dialog box to choose files
            File myfile=null;
            String path="";
        if(result==0){
            myfile=f.getSelectedFile();//selected file taken to myfile
            path=myfile.getAbsolutePath();//get the path of the file
        }
        IplImage src = cvLoadImage(path);//hear path is actual path to image
        IplImage grayImage    = IplImage.create(src.width(), src.height(), IPL_DEPTH_8U, 1);
        cvCvtColor(src, grayImage, CV_RGB2GRAY);
        cvThreshold(grayImage, grayImage, 127, 255, CV_THRESH_BINARY);
        CvSeq cvSeq=new CvSeq();
        CvMemStorage memory=CvMemStorage.create();
        cvFindContours(grayImage, memory, cvSeq, Loader.sizeof(CvContour.class), CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE);
        System.out.println(cvSeq.total());
        for (int i = 0; i < cvSeq.total(); i++) {
            CvRect rect=cvBoundingRect(cvSeq, i);
            int x=rect.x(),y=rect.y(),h=rect.height(),w=rect.width();
            if (10 < (w/h) || (w/h) < 0.1){
                cvRectangle(src, cvPoint(x, y), cvPoint(x+w, y+h), CvScalar.RED, 1, CV_AA, 0);
                //cvSeqPush(squares, rect);
            }
        }
        CanvasFrame cnvs=new CanvasFrame("Beam");
        cnvs.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
        cnvs.showImage(src);
        //cvShowImage("Final ", src);

    }
}

这是我得到的输出。请有人帮我解决这个问题吗？

This is the output that I got. Please can someone help me to solve this problem ?

推荐答案

编辑：这是最有趣的发现 -
我认为你没有正确迭代通过轮廓 - 你应该做类似的事情：

Here is the most interesting finding - I think you are not iterating correctly through the contours - you should do something like:

CvRect rect = cvBoundingRect(cvGetSeqElem(cvSeq, i),0); //python default?

或者：

// ... 
CvSeq contours = new CvSeq();
CvSeq ptr = new CvSeq();
CvRect rect = null;
// ...
cvFindContours(..., contours, ...);

for (ptr = contours; ptr != null; ptr = ptr.h_next()) {
    rect =  cvBoundingRect(ptr, 0);
    // ... Draw the box if meets criteria
}

首先，我认为pst对于比率的计算是正确的 - 你必须将宽度转换为浮动。

First, I think pst is right regarding the calculation of the ratio - you have to cast the width to float.

其次，我看到当你制作灰色图像时python你使用 COLOR_BGR2GRAY 而在java中你使用 CV_RGB2GRAY 可能导致完全不同的灰色图片。我会在两个程序上添加一些调试步骤来保存临时灰度图像，并将它们与 x，y，w 和 h 当（10 <（w / h）||（w / h）<0.1）为真时。

Secondly, I see that when you are making the gray image in python you use COLOR_BGR2GRAY and in java you are using CV_RGB2GRAY that could lead to a totally different gray picture. I would add some debug steps on both programs to save the temp gray images and compare them as also print outs for the values of x,y,w and h when (10 < (w/h) || (w/h) < 0.1) is true.

另一件事是在java解决方案中你使用 CV_RETR_CCOMP 来获取轮廓并在你使用的python解决方案中 CV_RETR_LIST 根据文档：

Another thing is that in the java solution you use CV_RETR_CCOMP to get the contours and in the python solution you use CV_RETR_LIST according to the documentation:

CV_RETR_LIST检索所有轮廓而不建立任何
层次关系CV_RETR_CCOMP检索所有轮廓
并将它们组织成两级层次结构：顶层是
组件的外部边界，第二层是
的孔边界。如果在连接组件的一个洞内
有另一个轮廓，它仍然会被放在顶层

CV_RETR_LIST retrieves all of the contours without establishing any hierarchical relationships CV_RETR_CCOMP retrieves all of the contours and organizes them into a two-level hierarchy: on the top level are the external boundaries of the components, on the second level are the boundaries of the holes. If inside a hole of a connected component there is another contour, it will still be put on the top level

所以首先，我会仔细检查两个程序中的所有cv参数是否相同，然后我会添加调试步骤以查看中间变量包含相同的数据。

So first I would double check that all cv's parameters in both programs are the same, then I would add debug steps to see that the intermediate variables contains the same data.

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