convert caffe::Datum to cv::Mat

DatumToCVMat

cv::Mat DatumToCVMat(const Datum& datum){
    int datum_channels = datum.channels();
    int datum_height = datum.height();
    int datum_width = datum.width();

    string strData = datum.data();
    cv::Mat cv_img;
    if (strData.size() != 0)
    {
        cv_img.create(datum_height, datum_width, CV_8UC(datum_channels));
        const string& data = datum.data();
        std::vector<char> vec_data(data.c_str(), data.c_str() + data.size());

        for (int h = 0; h < datum_height; ++h) {
            uchar* ptr = cv_img.ptr<uchar>(h);
            int img_index = 0;
            for (int w = 0; w < datum_width; ++w) {
                for (int c = 0; c < datum_channels; ++c) {
                    int datum_index = (c * datum_height + h) * datum_width + w;
                    ptr[img_index++] = static_cast<uchar>(vec_data[datum_index]);
                }
            }
        }
    }
    else
    {
        cv_img.create(datum_height, datum_width, CV_32FC(datum_channels));
        for (int h = 0; h < datum_height; ++h) {
            float* ptr = cv_img.ptr<float>(h);
            int img_index = 0;
            for (int w = 0; w < datum_width; ++w) {
                for (int c = 0; c < datum_channels; ++c) {
                    ptr[img_index++] = static_cast<float>(datum.float_data(img_index));
                }
            }
        }
    }
    return cv_img;
}