c++ - 在 opencv c++ 中查找图像卷积时出现段错误(核心转储)错误

Question

我是 opencv 的新手。我正在尝试使用与 opencv c++ 中的图像大小相同的内核对图像进行卷积。我收到错误“段错误(核心已转储)”。我检查了变量的初始化和循环。但我无法准确找出问题出在哪里。谁能帮我找出问题所在。我的代码如下:

#include<opencv2/highgui/highgui.hpp>
#include "opencv2/imgproc/imgproc.hpp"
#include<stdio.h>
#include<iostream>
#include<math.h>
#include<cv.hpp>

using namespace cv;
using namespace std;

Mat img;
Mat kernel, gd, dest;
int c = 120;
double mysum = 0.0, mysum1 = 0.0, k = 0;
int cent=0,radius=0;
enum ConvolutionType {   
    /* Return the full convolution, including border */
    CONVOLUTION_FULL, 

    /* Return only the part that corresponds to the original image */
    CONVOLUTION_SAME,

    /* Return only the submatrix containing elements that were not influenced by the       
    border       
    */
    CONVOLUTION_VALID
};

void conv2(const Mat &img, const Mat& kernel, ConvolutionType type,Mat& dest)
{

    Mat source = img;
    if(CONVOLUTION_FULL == type) 
    {
        source = Mat();
        const int additionalRows = kernel.rows - 1, additionalCols = kernel.cols - 1;
        copyMakeBorder(img, source, (additionalRows + 1) / 2, additionalRows / 2, 
            (additionalCols + 1) / 2, additionalCols / 2, BORDER_CONSTANT, Scalar(0));
    }

    flip(kernel, kernel, -1);
    Point anchor(kernel.cols - kernel.cols / 2 - 1, kernel.rows - kernel.rows / 2 - 1);
    int borderMode = BORDER_CONSTANT;
    filter2D(source, dest, img.depth(), kernel, anchor, 0, borderMode);

    if(CONVOLUTION_VALID == type)
    {
        dest = dest.colRange((kernel.cols - 1) / 2, dest.cols - kernel.cols / 2).rowRange((kernel.rows - 1) / 2, dest.rows - kernel.rows / 2);
    }
} 

int main()
{  
    img = imread("building1.jpg", CV_LOAD_IMAGE_COLOR);
    dest.create(img.size(), img.type());
    gd.create(img.size(), img.type());

    for(int j = 0; j < img.rows; j++)
    {
        for(int i = 0; i < img.cols; i++)
        {
            radius = ((cent - i)^2 + (cent - j)^2);
            gd.at<float>(j, i) = exp((-(radius) / c^2));

            mysum = mysum + gd.at<float>(j, i);
        }
        mysum1 = mysum1 + mysum; 
    }

    k=1/mysum1;
    cout<<endl<<k<<"\n"<<endl;

    for(int j = 0; j < img.rows; j++)
    {
        for(int i = 0; i < img.cols; i++)
        {
            gd.at<float>(j, i) = k * gd.at<float>(j, i);
        }
    }  

    conv2(img, gd, CONVOLUTION_FULL, dest);
    imshow("conv", dest);
    waitKey(0);
    return 0;
}

Answer 1

当您创建 img 时

img = imread("building1.jpg", CV_LOAD_IMAGE_COLOR);

它将是 CV_UC3 类型，即每个像素 3 个字节(蓝色、绿色和红色各一个字节)。

但是当你访问图片时

gd.at<float>(j, i) = k * gd.at<float>(j, i);

您正在使用浮点指针。由于 float 是 4 个字节，而不是 3 个字节，因此您最终会访问图像之外的内存，甚至是您的程序。后者正在发生，如分段违规所示。

最好的办法可能是在 Debug模式下编译您的代码。那么您可能会从 OpenCV 中得到一个异常，而不是分段违规。

看起来你可能想要的是

img = imread("building1.jpg", CV_LOAD_IMAGE_GRAYSCALE);
img.convertTo(img, CV_32FC1); 
...

还有一些代码可以大大简化，例如

for(int j = 0; j < img.rows; j++)
{
    for(int i = 0; i < img.cols; i++)
    {
        gd.at<float>(j, i) = k * gd.at<float>(j, i);
    }
}  

应该是

gd = gd * k;

如果您按顺序访问像素，请使用 at<>()效率很低。参见 the efficient way