cv :: resize()失败，并出现访问冲突错误(由< struct in NULL>引起)

由于@Micka在评论中的建议，我发现原因首先是由于发送到preprocess方法的图像而不是resize方法本身.
进一步的调试证明了@Micka对C#侧错误代码的怀疑. 我最初是在C#端写的:

Thanks to @Micka's suggestions in the comments, I found out the cause was first due to the image that was sent to the preprocess method and not the resize method by itself.
Further debugging proved @Micka's suspicion about the faulty code on C# side. I was originally wrote in the C# side :

[DllImport(@"CDll2.dll", CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
static extern void Classify_image(byte[] img, uint height, uint width, byte[] out_result, out int out_result_length, int top_n_results = 2);

private string Classify(Bitmap img, int top_n_results)
{
    byte[] result = new byte[200];
    int len;
    var img_byte = (byte[])(new ImageConverter()).ConvertTo(img, typeof(byte[]));

    Classify_image(img_byte, (uint)img.Height, (uint)img.Width,res, out len, top_n_results);

    return  ASCIIEncoding.ASCII.GetString(result);
}

这是dll部分的代码:

CDLL2_API void Classify_image(unsigned char* img_pointer, unsigned int height, unsigned int width, char* out_result, int* length_of_out_result, int top_n_results)
    {
        auto classifier = reinterpret_cast<Classifier*>(GetHandle());
        cv::Mat img = cv::Mat(height, width, CV_32FC3, (void*)img_pointer);

        std::vector<Prediction> result = classifier->Classify(img, top_n_results);

        //misc code...
        *length_of_out_result = ss.str().length();
    }

这被证明是错误的，或者至少是越野车.使用此代码，C++侧上的图像似乎已正确初始化，通道数，高度和宽度似乎都很好.
但是，当您尝试通过调整大小甚至使用imshow()来显示图像时，它会使应用程序崩溃并给出访问冲突异常，该错误与调整大小时发生的错误相同，并发布在问题中. .
看着答案，我更改了负责将图像传递到dll的C#代码.新代码如下:

This proved to be plain wrong, or at the very least buggy. Using this code, the image on the C++ side seemed to have been initialized properly, the number of channels, the height, and width all seemed fine.
But the moment you attempt to use the image, either by resizing it or even showing it using imshow(), it would crash the application and be giving an access violation exception, the very same error that happened when resizing and is posted in the question.
Looking at this answer, I changed the C# code responsible for handing the image to the dll. the new code is as follows :

//Dll import 
[DllImport(@"CDll2.dll", CallingConvention = CallingConvention.Cdecl, CharSet = CharSet.Ansi)]
static extern void Classify_Image(IntPtr img, uint height, uint width, int step, byte[] out_result, out int out_result_length, int top_n_results = 2);

//...
//main code 

Bitmap img = new Bitmap(txtImagePath.Text);
BitmapData bmpData = img.LockBits(new Rectangle(0, 0, img.Width, img.Height),  ImageLockMode.ReadWrite,  img.PixelFormat);
result = Classify_Image(bmpData.Scan0, (uint)bmpData.Height, (uint)bmpData.Width, bmpData.Stride, res, out len, top_n_results);
img.UnlockBits(bmpData); //Remember to unlock!!!

和DLL中的C ++代码:

and the C++ code in the DLL :

CDLL2_API void Classify_Image(unsigned char* img_pointer, unsigned int height, unsigned int width, int step, char* out_result, int* length_of_out_result, int top_n_results)
    {
        auto classifier = reinterpret_cast<Classifier*>(GetHandle());

        cv::Mat img = cv::Mat(height, width, CV_8UC3, (void*)img_pointer, step);

        std::vector<Prediction> result = classifier->Classify(img, top_n_results);

        //...
        *length_of_out_result = ss.str().length();
    }

并纠正了我以前遇到的所有访问冲突.

and doing so rectified all access violations I was getting previously.