C++ 方形检测不';我找不到正方形
我正在使用OpenCV库示例中提供的程序squares.c。它适用于所有图像,但我真的不明白为什么它不能识别该图像中绘制的正方形 在精明之后: 扩张后: 结果图像(红色) 如您所见,没有检测到正方形C++ 方形检测不';我找不到正方形,c++,c,opencv,image-processing,object-detection,C++,C,Opencv,Image Processing,Object Detection,我正在使用OpenCV库示例中提供的程序squares.c。它适用于所有图像,但我真的不明白为什么它不能识别该图像中绘制的正方形 在精明之后: 扩张后: 结果图像(红色) 如您所见,没有检测到正方形 检测后,我需要提取正方形中包含的区域…没有ROI怎么可能?我建议您在这张图像中的正方形太薄。在squares.c中的第一步是缩小图像的比例,并在传递到Canny边缘检测器之前进行备份以减少噪声 缩放卷积为5x5内核,因此在您的情况下,这可能会导致在如此薄的边上丢失任何梯度 如果要将正方形边缘
检测后,我需要提取正方形中包含的区域…没有ROI怎么可能?我建议您在这张图像中的正方形太薄。在squares.c中的第一步是缩小图像的比例,并在传递到Canny边缘检测器之前进行备份以减少噪声 缩放卷积为5x5内核,因此在您的情况下,这可能会导致在如此薄的边上丢失任何梯度
如果要将正方形边缘覆盖在连续背景上,请尝试使其至少有5个像素。下面的源代码提供了正方形检测器程序的一个小变化。它并不完美,但它说明了解决问题的一种方法 您可以将此代码与原始代码区分开来,并检查所做的所有更改,但主要更改有:
- 将阈值级别的数量减少到2
- 在
的开头,对图像进行放大,以检测薄的白色正方形,然后模糊整个图像,这样算法就不会将海洋和天空作为单个正方形进行检测findSquares()
/app
//方形探测器”程序。
//它按顺序加载多个图像,并尝试在图像中查找正方形
//每张图片
#包括“highgui.h”
#包括“cv.h”
#包括
#包括
#包括
使用名称空间cv;
使用名称空间std;
无效帮助()
{
库特1000&&
isContourConvex(材料(近似)))
{
双最大余弦=0;
对于(int j=2;j<5;j++)
{
//求关节边之间角度的最大余弦
双余弦=fabs(角度(约[j%4],约[j-2],约[j-1]);
最大余弦=最大值(最大余弦,余弦);
}
//如果所有角度的余弦都很小
//(所有角度约为90度)然后写入量子线
//结果序列的顶点
如果(最大余弦<0.3)
正方形。推回(大约);
}
}
}
}
}
//该函数用于绘制图像中的所有正方形
空心绘图方块(材质和图像、常量向量和方块)
{
对于(size_t i=0;i 不幸的是,正方形已经画出来了,我只需要提取它谢谢你karlphillip…通过你的更正,现在脚本工作正常。但是如果我想提取一个子图像,只包含正方形中包含的区域,有可能吗?(在这种情况下,我们没有ROI,只有一系列正方形)是的,您需要从一组4个cv::Point
创建一个cv::Mat
。因为Stackoverflow不是聊天,所以让我们每个线程保留一个问题。如果您有更多问题,可以在新线程中自由提问。但为了说明此情况下的过程,因为应用程序有一个正方形向量,您应该做一些ike:for(size_t x=0;x
它将为原始图像中检测到的所有正方形生成一个名为子图像的新Mat。请记住:图像中检测到的点可能并不代表完美的正方形(如上图所示)但是我刚才给你的代码是假设它们是这样的。卡尔,谢谢你的好意。正如你建议的那样,我创建了一个新的线程:你的图像似乎丢失了。你有没有可能重新加载或重新创建它们?
// The "Square Detector" program.
// It loads several images sequentially and tries to find squares in
// each image
#include "highgui.h"
#include "cv.h"
#include <iostream>
#include <math.h>
#include <string.h>
using namespace cv;
using namespace std;
void help()
{
cout <<
"\nA program using pyramid scaling, Canny, contours, contour simpification and\n"
"memory storage (it's got it all folks) to find\n"
"squares in a list of images pic1-6.png\n"
"Returns sequence of squares detected on the image.\n"
"the sequence is stored in the specified memory storage\n"
"Call:\n"
"./squares\n"
"Using OpenCV version %s\n" << CV_VERSION << "\n" << endl;
}
int thresh = 50, N = 2; // karlphillip: decreased N to 2, was 11.
const char* wndname = "Square Detection Demo";
// helper function:
// finds a cosine of angle between vectors
// from pt0->pt1 and from pt0->pt2
double angle( Point pt1, Point pt2, Point pt0 )
{
double dx1 = pt1.x - pt0.x;
double dy1 = pt1.y - pt0.y;
double dx2 = pt2.x - pt0.x;
double dy2 = pt2.y - pt0.y;
return (dx1*dx2 + dy1*dy2)/sqrt((dx1*dx1 + dy1*dy1)*(dx2*dx2 + dy2*dy2) + 1e-10);
}
// returns sequence of squares detected on the image.
// the sequence is stored in the specified memory storage
void findSquares( const Mat& image, vector<vector<Point> >& squares )
{
squares.clear();
Mat pyr, timg, gray0(image.size(), CV_8U), gray;
// karlphillip: dilate the image so this technique can detect the white square,
Mat out(image);
dilate(out, out, Mat(), Point(-1,-1));
// then blur it so that the ocean/sea become one big segment to avoid detecting them as 2 big squares.
medianBlur(out, out, 7);
// down-scale and upscale the image to filter out the noise
pyrDown(out, pyr, Size(out.cols/2, out.rows/2));
pyrUp(pyr, timg, out.size());
vector<vector<Point> > contours;
// find squares in every color plane of the image
for( int c = 0; c < 3; c++ )
{
int ch[] = {c, 0};
mixChannels(&timg, 1, &gray0, 1, ch, 1);
// try several threshold levels
for( int l = 0; l < N; l++ )
{
// hack: use Canny instead of zero threshold level.
// Canny helps to catch squares with gradient shading
if( l == 0 )
{
// apply Canny. Take the upper threshold from slider
// and set the lower to 0 (which forces edges merging)
Canny(gray0, gray, 0, thresh, 5);
// dilate canny output to remove potential
// holes between edge segments
dilate(gray, gray, Mat(), Point(-1,-1));
}
else
{
// apply threshold if l!=0:
// tgray(x,y) = gray(x,y) < (l+1)*255/N ? 255 : 0
gray = gray0 >= (l+1)*255/N;
}
// find contours and store them all as a list
findContours(gray, contours, CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE);
vector<Point> approx;
// test each contour
for( size_t i = 0; i < contours.size(); i++ )
{
// approximate contour with accuracy proportional
// to the contour perimeter
approxPolyDP(Mat(contours[i]), approx, arcLength(Mat(contours[i]), true)*0.02, true);
// square contours should have 4 vertices after approximation
// relatively large area (to filter out noisy contours)
// and be convex.
// Note: absolute value of an area is used because
// area may be positive or negative - in accordance with the
// contour orientation
if( approx.size() == 4 &&
fabs(contourArea(Mat(approx))) > 1000 &&
isContourConvex(Mat(approx)) )
{
double maxCosine = 0;
for( int j = 2; j < 5; j++ )
{
// find the maximum cosine of the angle between joint edges
double cosine = fabs(angle(approx[j%4], approx[j-2], approx[j-1]));
maxCosine = MAX(maxCosine, cosine);
}
// if cosines of all angles are small
// (all angles are ~90 degree) then write quandrange
// vertices to resultant sequence
if( maxCosine < 0.3 )
squares.push_back(approx);
}
}
}
}
}
// the function draws all the squares in the image
void drawSquares( Mat& image, const vector<vector<Point> >& squares )
{
for( size_t i = 0; i < squares.size(); i++ )
{
const Point* p = &squares[i][0];
int n = (int)squares[i].size();
polylines(image, &p, &n, 1, true, Scalar(0,255,0), 3, CV_AA);
}
imshow(wndname, image);
}
int main(int argc, char** argv)
{
if (argc < 2)
{
cout << "Usage: ./program <file>" << endl;
return -1;
}
// static const char* names[] = { "pic1.png", "pic2.png", "pic3.png",
// "pic4.png", "pic5.png", "pic6.png", 0 };
static const char* names[] = { argv[1], 0 };
help();
namedWindow( wndname, 1 );
vector<vector<Point> > squares;
for( int i = 0; names[i] != 0; i++ )
{
Mat image = imread(names[i], 1);
if( image.empty() )
{
cout << "Couldn't load " << names[i] << endl;
continue;
}
findSquares(image, squares);
drawSquares(image, squares);
imwrite("out.jpg", image);
int c = waitKey();
if( (char)c == 27 )
break;
}
return 0;
}