cvtColor 断言失败（使用 C++ 的 OpenCV）抛出实例 cv::exception

Posted 2023-02-22

【中文标题】cvtColor 断言失败（使用 C++ 的 OpenCV）抛出实例 cv::exception

【英文标题】：cvtColor assertion failed ( OpenCV with C++ ) throwing an instance cv::exception

【发布时间】：2014-04-07 14:00:24

【问题描述】：

我用opencv和c++做了一个运动检测程序，我得到了这个错误

root@raspberrypi:/home/pi/motion_src/src# OpenCV Error: Assertion failed (scn == 3 || scn == 4) in cvtColor, file /usr/src/packages/BUILD/opencv-2.4.1+dfsg/modules/imgproc/src/color.cpp, line 3205

在抛出 'cv::Exception' 实例后调用终止 什么（）：/usr/src/packages/BUILD/opencv-2.4.1+dfsg/modules/imgproc/src/color.cpp:3205：错误：（-215）scn == 3 ||函数 cvtColor 中的 scn == 4

这是我的源代码

// Take images and convert them to gray
Mat result, result_cropped;
Mat prev_frame = result = cvQueryFrame(camera);
Mat current_frame = cvQueryFrame(camera);
Mat next_frame = cvQueryFrame(camera);
cvtColor(current_frame, current_frame, CV_RGB2GRAY);
cvtColor(prev_frame, prev_frame, CV_RGB2GRAY);
cvtColor(next_frame, next_frame, CV_RGB2GRAY);

// d1 and d2 for calculating the differences
// result, the result of and operation, calculated on d1 and d2
// number_of_changes, the amount of changes in the result matrix.
// color, the color for drawing the rectangle when something has changed.
Mat d1, d2, motion;
int number_of_changes, number_of_sequence = 0;
Scalar mean_, color(0,255,255); // yellow

// Detect motion in window
int x_start = 10, x_stop = current_frame.cols-11;
int y_start = 350, y_stop = 530;

// If more than 'there_is_motion' pixels are changed, we say there is motion
// and store an image on disk
int there_is_motion = 5;

// Maximum deviation of the image, the higher the value, the more motion is allowed
int max_deviation = 20;

// Erode kernel
Mat kernel_ero = getStructuringElement(MORPH_RECT, Size(2,2));

// All settings have been set, now go in endless loop and
// take as many pictures you want..
while (true)
    // Take a new image
    prev_frame = current_frame;
    current_frame = next_frame;
    next_frame = cvQueryFrame(camera);
    result = next_frame;
    cvtColor(next_frame, next_frame, CV_RGB2GRAY);

    // Calc differences between the images and do AND-operation
    // threshold image, low differences are ignored (ex. contrast change due to sunlight)
    absdiff(prev_frame, next_frame, d1);
    absdiff(next_frame, current_frame, d2);
    bitwise_and(d1, d2, motion);
    threshold(motion, motion, 35, 255, CV_THRESH_BINARY);
    erode(motion, motion, kernel_ero);

    number_of_changes = detectMotion(motion, result, result_cropped,  x_start, x_stop, y_start, y_stop, max_deviation, color);

    // If a lot of changes happened, we assume something changed.
    if(number_of_changes>=there_is_motion)
    
        if(number_of_sequence>0) 
            saveImg(result,DIR,EXT,DIR_FORMAT.c_str(),FILE_FORMAT.c_str());
            saveImg(result_cropped,DIR,EXT,DIR_FORMAT.c_str(),CROPPED_FILE_FORMAT.c_str());
        
        number_of_sequence++;
    
    else
    
        number_of_sequence = 0;
        // Delay, wait a 1/2 second.
        cvWaitKey (DELAY);
    

return 0;    

【问题讨论】：

请使用 camera.read(frame)，而不是 cvQueryFrame。避免使用旧的 c-api 函数。在应用 cvtColor

之前还要检查返回值或 frame.empty()

【参考方案1】：

“cvtColor”函数期望输入图像具有 3 或 4 个通道，用于您使用的转换类型 (CV_RGB2GRAY) - 这就是投诉的内容。检查输入是否满足此条件（或不为空）。

另外，由于您要更改通道数，我不确定是否可以使用该函数“就地”工作 - 您可能应该为函数的结果创建一个新变量。

color.cpp 源供参考 - https://github.com/Itseez/opencv/blob/master/modules/imgproc/src/color.cpp