Exception in stitching object (Bug #2744)

Hi Alexey,

I mean crashing application:

About CV_8UC3. I think this is another case, because I case no problem with the same images with this code:

int main(int argc, char* argv[])
{
    int retval = parseCmdArgs(argc, argv);
    if (retval) return -1;

    Mat pano;

    cv::Rect rect1 = cvRect(3*imgs[0].cols/4, imgs[0].rows/3, imgs[0].cols/4, imgs[0].rows/2); //second half of the first image
    cv::vector<cv::Rect> roi1;
    roi1.push_back(rect1);

    cv::Rect rect12 = cvRect(0, imgs[1].rows/3, imgs[1].cols/4, 2*imgs[1].rows/3); //first half of the second image
    cv::Rect rect23 = cvRect(3*imgs[1].cols/4, imgs[1].rows/3, imgs[1].cols/4, imgs[1].rows/2); //second half of the first image
    cv::vector<cv::Rect> roi2;
    roi2.push_back(rect12);
    roi2.push_back(rect23);

    cv::Rect rect3 = cvRect(0, imgs[2].rows/3, imgs[2].cols/4, imgs[2].rows/2); //first half of the third image
    cv::vector<cv::Rect> roi3;
    roi3.push_back(rect3);

    cv::vector<cv::vector<cv::Rect>> rois;
    rois.resize(3);
    rois[0] = roi1;
    rois[1] = roi2;
    rois[2] = roi3;

    Stitcher stitcher = Stitcher::createDefault(true);
    Stitcher::Status status = stitcher.stitch(imgs, rois, pano);
    //Stitcher::Status status = stitcher.composePanorama(imgs, pano);

    if (status != Stitcher::OK)
    {
        cout << "Can't stitch images, error code = " << status << endl;
        return -1;
    }

    return 0;
}

Hm, looks like you are right. Should I convert Mats from CV_8UC1 to CV_8UC3 before stitching?

Mat image11, image22, image33;
    Mat image1(height, width, CV_8UC1, (unsigned char*) captureClient->bList.at(0).data());
    image1.convertTo(image11, CV_8UC3); 
    imgs.push_back(image11);

Converting images to 8UC3 should resolve the issue. Here is a way to do it:

Mat img(height, width, CV_8U, (uchar*)captureClient->bList.at(0).data());
cvtColor(img, img, CV_GRAY2BGR);
imgs.push_back(img);

OpenCV functions throw exceptions when something is wrong, usually it helps to understand the cause of issue:

try { /*OpenCV calls*/ } catch (const cv::Exception &e) { cout << e.what() << endl; }

Thank you for you help Alexey! Now it works.
Do you planing to update stitching module for 8-bit images?
Now it looks like not very wise to convert 8-bit to 24-bit images only for stitching purposes,
for large images I'll loose more memory and CPU/GPU time.

Done. Feature #2752