void RadiometricResponse::directMap(cv::InputArray _E, cv::OutputArray _I) const {
if (_E.empty()) {
_I.clear();
return;
}
auto E = _E.getMat();
_I.create(_E.size(), CV_8UC3);
auto I = _I.getMat();
#if CV_MAJOR_VERSION > 2
E.forEach<cv::Vec3f>(
[&I, this](cv::Vec3f& v, const int* p) { I.at<cv::Vec3b>(p[0], p[1]) = inverseLUT(response_channels_, v); });
#else
for (int i = 0; i < E.rows; i++)
for (int j = 0; j < E.cols; j++) I.at<cv::Vec3b>(i, j) = inverseLUT(response_channels_, E.at<cv::Vec3f>(i, j));
#endif
}
