vendor: OpenCV 5.0.0 snapshot at 755e50675d97db9b7d449d8bd6b09888646f6c6e

modules/quality/src/qualityssim.cpp

@@ -0,0 +1,118 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#include "precomp.hpp"
+#include "opencv2/quality/qualityssim.hpp"
+#include "opencv2/imgproc.hpp"  // GaussianBlur
+#include "opencv2/quality/quality_utils.hpp"
+
+namespace
+{
+    using namespace cv;
+    using namespace cv::quality;
+
+    using _mat_type = UMat;
+    using _quality_map_type = _mat_type;
+
+    // SSIM blur function
+    _mat_type blur(const _mat_type& mat)
+    {
+        _mat_type result = {};
+        cv::GaussianBlur( mat, result, cv::Size(11, 11), 1.5 );
+        return result;
+    }
+}   // ns
+
+QualitySSIM::_mat_data::_mat_data( const _mat_type& mat )
+{
+    this->I = mat;
+    cv::multiply(this->I, this->I, this->I_2);
+    this->mu = ::blur(this->I);
+    cv::multiply(this->mu, this->mu, this->mu_2);
+    this->sigma_2 = ::blur(this->I_2);    // blur the squared img, subtract blurred_squared
+    cv::subtract(this->sigma_2, this->mu_2, this->sigma_2);
+}
+
+QualitySSIM::_mat_data::_mat_data(InputArray arr )
+    : _mat_data( quality_utils::expand_mat<mat_type>(arr) )    // delegate
+{}
+
+// static
+Ptr<QualitySSIM> QualitySSIM::create( InputArray ref )
+{
+    return Ptr<QualitySSIM>(new QualitySSIM( _mat_data( ref )));
+}
+
+// static
+cv::Scalar QualitySSIM::compute( InputArray ref, InputArray cmp, OutputArray qualityMap )
+{
+    auto result = _mat_data::compute( _mat_data(ref), _mat_data(cmp) );
+
+    if (qualityMap.needed())
+        qualityMap.assign(result.second);
+
+    return result.first;
+}
+
+cv::Scalar QualitySSIM::compute( InputArray cmp )
+{
+    auto result = _mat_data::compute(
+        this->_refImgData
+        , _mat_data(cmp)
+    );
+
+    OutputArray(this->_qualityMap).assign(result.second);
+    return result.first;
+}
+
+// static.  computes ssim and quality map for single frame
+// based on https://docs.opencv.org/2.4/doc/tutorials/highgui/video-input-psnr-ssim/video-input-psnr-ssim.html
+std::pair<cv::Scalar, _mat_type> QualitySSIM::_mat_data::compute(const _mat_data& lhs, const _mat_data& rhs)
+{
+    const double
+        C1 = 6.5025
+        , C2 = 58.5225
+        ;
+
+    mat_type
+        I1_I2
+        , mu1_mu2
+        , t1
+        , t2
+        , t3
+        , sigma12
+        ;
+
+    cv::multiply(lhs.I, rhs.I, I1_I2);
+    cv::multiply(lhs.mu, rhs.mu, mu1_mu2);
+    cv::subtract(::blur(I1_I2), mu1_mu2, sigma12);
+
+    // t3 = ((2*mu1_mu2 + C1).*(2*sigma12 + C2))
+    cv::multiply(mu1_mu2, 2., t1);
+    cv::add(t1, C1, t1);// t1 += C1
+
+    cv::multiply(sigma12, 2., t2);
+    cv::add(t2, C2, t2);// t2 += C2
+
+    // t3 = t1 * t2
+    cv::multiply(t1, t2, t3);
+
+    // t1 =((mu1_2 + mu2_2 + C1).*(sigma1_2 + sigma2_2 + C2))
+    cv::add(lhs.mu_2, rhs.mu_2, t1);
+    cv::add(t1, C1, t1);
+
+    cv::add(lhs.sigma_2, rhs.sigma_2, t2);
+    cv::add(t2, C2, t2);
+
+    // t1 *= t2
+    cv::multiply(t1, t2, t1);
+
+    // quality map: t3 /= t1
+    cv::divide(t3, t1, t3);
+
+    return {
+        cv::mean(t3)
+        , std::move(t3)
+    };
+}   // compute