Add overloaded cv::PCACompute() that returns also the eigenvalues. Useful for Java and Python OpenCV where PCA is not available.

modules/core/include/opencv2/core.hpp

@@ -1978,10 +1978,20 @@ CV_EXPORTS_W void calcCovarMatrix( InputArray samples, OutputArray covar,
 CV_EXPORTS_W void PCACompute(InputArray data, InputOutputArray mean,
                              OutputArray eigenvectors, int maxComponents = 0);
 
+/** wrap PCA::operator() and add eigenvalues output parameter */
+CV_EXPORTS_AS(PCACompute2) void PCACompute(InputArray data, InputOutputArray mean,
+                                           OutputArray eigenvectors, OutputArray eigenvalues,
+                                           int maxComponents = 0);
+
 /** wrap PCA::operator() */
 CV_EXPORTS_W void PCACompute(InputArray data, InputOutputArray mean,
                              OutputArray eigenvectors, double retainedVariance);
 
+/** wrap PCA::operator() and add eigenvalues output parameter */
+CV_EXPORTS_AS(PCACompute2) void PCACompute(InputArray data, InputOutputArray mean,
+                                           OutputArray eigenvectors, OutputArray eigenvalues,
+                                           double retainedVariance);
+
 /** wrap PCA::project */
 CV_EXPORTS_W void PCAProject(InputArray data, InputArray mean,
                              InputArray eigenvectors, OutputArray result);

modules/core/src/pca.cpp

@@ -360,6 +360,19 @@ void cv::PCACompute(InputArray data, InputOutputArray mean,
     pca.eigenvectors.copyTo(eigenvectors);
 }
 
+void cv::PCACompute(InputArray data, InputOutputArray mean,
+                    OutputArray eigenvectors, OutputArray eigenvalues,
+                    int maxComponents)
+{
+    CV_INSTRUMENT_REGION()
+
+    PCA pca;
+    pca(data, mean, 0, maxComponents);
+    pca.mean.copyTo(mean);
+    pca.eigenvectors.copyTo(eigenvectors);
+    pca.eigenvalues.copyTo(eigenvalues);
+}
+
 void cv::PCACompute(InputArray data, InputOutputArray mean,
                     OutputArray eigenvectors, double retainedVariance)
 {
@@ -371,6 +384,19 @@ void cv::PCACompute(InputArray data, InputOutputArray mean,
     pca.eigenvectors.copyTo(eigenvectors);
 }
 
+void cv::PCACompute(InputArray data, InputOutputArray mean,
+                    OutputArray eigenvectors, OutputArray eigenvalues,
+                    double retainedVariance)
+{
+    CV_INSTRUMENT_REGION()
+
+    PCA pca;
+    pca(data, mean, 0, retainedVariance);
+    pca.mean.copyTo(mean);
+    pca.eigenvectors.copyTo(eigenvectors);
+    pca.eigenvalues.copyTo(eigenvalues);
+}
+
 void cv::PCAProject(InputArray data, InputArray mean,
                     InputArray eigenvectors, OutputArray result)
 {