Valgrind的无效读取大小4（OpenCV的）的

Question

这里是我的代码：

template <typename TValue> 
std::vector<cv::Point2i> GetPixelsWithValue(const cv::Mat& image, const TValue& value) { 
    std::vector<cv::Point2i> pixels; 
    cv::Size imageSize = image.size(); 
    for(int i = 0; i < imageSize.height; ++i) { 
     for(int j = 0; j < imageSize.width; ++j) { 
      if(image.at<TValue>(i, j) == value) { 
       cv::Point2i pixel(j, i); 
       pixels.push_back(pixel); 
      } 
     } 
    } 

    return pixels; 
} 

Valgrind是给这个错误：

==10655== Conditional jump or move depends on uninitialised value(s) 
==10655== at 0x4E88517: GetPixelsWithValue<int> (OpenCVExtensions.hpp:18) 
==10655== by 0x4E88517: CountPixelsWithValue<int> (OpenCVExtensions.hpp:31) 
... 
==10655== Uninitialised value was created by a heap allocation 
==10655== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==10655== by 0x117138EB: cv::fastMalloc(unsigned long) (alloc.cpp:64) 
==10655== by 0x1184F795: cv::StdMatAllocator::allocate(int, int const*, int, void*, unsigned long*, int, cv::UMatUsageFlags) const (matrix.cpp:192) 
==10655== by 0x118507BE: cv::Mat::create(int, int const*, int) (matrix.cpp:426) 
==10655== by 0x4E9BA31: create (mat.inl.hpp:684) 
==10655== by 0x4E9BA31: Mat (mat.inl.hpp:351) 
==10655== by 0x4E9BA31: cv::Mat 
....  
==10655== Invalid read of size 4 
==10655== at 0x4E88510: GetPixelsWithValue<int> (OpenCVExtensions.hpp:18) 
.... 
==10655== Address 0x23201c92 is 127,346 bytes inside a block of size 127,347 alloc'd 
==10655== at 0x4C2AB80: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so) 
==10655== by 0x117138EB: cv::fastMalloc(unsigned long) (alloc.cpp:64) 
==10655== by 0x1184F795: cv::StdMatAllocator::allocate(int, int const*, int, void*, unsigned long*, int, cv::UMatUsageFlags) const (matrix.cpp:192) 
==10655== by 0x118507BE: cv::Mat::create(int, int const*, int) (matrix.cpp:426) 
==10655== by 0x4E9BA31: create (mat.inl.hpp:684) 
==10655== by 0x4E9BA31: Mat (mat.inl.hpp:351) 

我发现这些和更多：

Why am I getting memory errors when accessing this matrix in OpenCV?

Invalid write size of 4 with matrix class (using valgrind)

但是我不明白为什么我得到错误。这可能是内部来自OpenCV的错误吗？

Answer 1

发现此问题。正如@Kerrek SB指出的那样，图像是个问题。下面是一个更完整的例子。似乎未初始化值错误是由于尝试使用未初始化的矩阵。我也可能有超出范围的索引，导致无效的读取错误。

#include "opencv2/highgui/highgui.hpp" 
#include <iostream> 

using namespace std; 
using namespace cv; 

std::vector<cv::Point2i> GetPixelsWithValue(const cv::Mat1b& image, const unsigned char& value) { 
    std::vector<cv::Point2i> pixels; 
    cv::Size imageSize = image.size(); 
    for(int i = 0; i < imageSize.height; ++i) { 
     for(int j = 0; j < imageSize.width; ++j) { 
      if(image.at<unsigned char>(i, j) == value) { 
       cv::Point2i pixel(j, i); 
       pixels.push_back(pixel); 
      } 
     } 
    } 

    return pixels; 
} 

int main() 
{ 

    cv::Mat1b image(10, 12); 
    image.setTo(0); //enable this and all the uninitialized value errors go away 

    image(0,1) = 63; 
    image(1,3) = 63; 
    image(3,5) = 63; 
    image(4,7) = 63; 
    image(5,9) = 63; 
// image(10,12) = 63; //causes invalid write error 

    std::vector<cv::Point2i> vec = GetPixelsWithValue(image, static_cast<unsigned char>(63)); 

    std::cout << image(10,12) << std::endl; //bad access. causes invalid read error only 
    std::cout << vec.size() << std::endl; 

    return 0; 
}