记录一下用到的cv::mat和qimage互转方法

cv::mat to qimage

QImage cvMat2QImage(const cv::Mat& mat)
{
    QImage image;

    if(mat.empty()){
        return image;
    }

    switch (mat.depth())
    {
        case CV_8U:
            if (mat.channels() == 1) {
                // Grayscale 8-bit
                image = QImage(mat.data, mat.cols, mat.rows, mat.step, QImage::Format_Grayscale8);
            } else if (mat.channels() == 3) {
                // 8-bit BGR
                image = QImage(mat.data, mat.cols, mat.rows, mat.step, QImage::Format_BGR888);
            } else if (mat.channels() == 4) {
                // 8-bit BGRA
                image = QImage(mat.data, mat.cols, mat.rows, mat.step, QImage::Format_ARGB32);
            } else {
                image = QImage(QSize(mat.cols, mat.rows), QImage::Format::Format_ARGB32_Premultiplied);
                image.fill(Qt::gray);
            }
            break;

        case CV_8S: 
            {
                // Convert signed 8-bit to unsigned
                cv::Mat matConverted;
                mat.convertTo(matConverted, CV_8U, 1.0, 128); // Shift [-128, 127] to [0, 255]
                image = QImage(matConverted.data, matConverted.cols, matConverted.rows, matConverted.step, QImage::Format_Grayscale8).copy();
                break;
            }

        case CV_16U: 
            {
                if (mat.channels() == 4) {
                    image = QImage((const uchar*)mat.data, mat.cols, mat.rows, mat.step, QImage::Format_RGBA64);
                }else{
                    image = QImage(QSize(mat.cols, mat.rows), QImage::Format_ARGB32_Premultiplied);
                    image.fill(Qt::gray); // Placeholder image
                }
                break;
            }

        case CV_32F:
            {
                cv::Mat convert;
                cv::normalize(mat, convert, 0, 255, cv::NORM_MINMAX, CV_8UC3);
                image = cvMat2QImage(convert);
                break;
            }   

        default:
            // log(u8"不支持的mat类型：" + std::to_string(mat.type()));

            image = QImage(QSize(mat.cols, mat.rows), QImage::Format_ARGB32_Premultiplied);
            image.fill(Qt::gray); // Placeholder image
            break;
    }
    
    return image.copy();	//使用copy返回，防止mat析构后崩溃
}

qiamge to cv::mat

这部分的内容来源自网络

cv::Mat QImage2cvMat(const QImage& image)
{
    cv::Mat mat;
    switch (image.format())
    {
        case QImage::Format_Grayscale8: // 灰度图，每个像素点1个字节（8位）
            // Mat构造：行数，列数，存储结构，数据，step每行多少字节
            mat = cv::Mat(image.height(), image.width(), CV_8UC1, (void*)image.constBits(), image.bytesPerLine());
            break;
        case QImage::Format_ARGB32: // uint32存储0xAARRGGBB，pc一般小端存储低位在前，所以字节顺序就成了BGRA
        case QImage::Format_RGB32: // Alpha为FF
        case QImage::Format_ARGB32_Premultiplied:
            mat = cv::Mat(image.height(), image.width(), CV_8UC4, (void*)image.constBits(), image.bytesPerLine());
            break;
        case QImage::Format_RGB888: // RR,GG,BB字节顺序存储
            mat = cv::Mat(image.height(), image.width(), CV_8UC3, (void*)image.constBits(), image.bytesPerLine());
            // opencv需要转为BGR的字节顺序
            cv::cvtColor(mat, mat, cv::COLOR_RGB2BGR);
            break;
        case QImage::Format_RGBA64: // uint64存储，顺序和Format_ARGB32相反，RGBA
            mat = cv::Mat(image.height(), image.width(), CV_16UC4, (void*)image.constBits(), image.bytesPerLine());
            // opencv需要转为BGRA的字节顺序
            cv::cvtColor(mat, mat, cv::COLOR_RGBA2BGRA);
            break;
    }
    return mat;
}