2017-07-30 20:24:54 -0600 commented answer mat type = 15 is not supported Thank you so much!! It works 2017-07-28 05:06:51 -0600 asked a question mat type = 15 is not supported I got an error while changing an eigenvector as an image def getEigenVectorsAndEigenValues(covarianceMatx): print("Compute Eigens...") logger.info("Compute Eigens...") eigenSolution = np.linalg.eig(covarianceMatx) # print("len eigenSolution", len(eigenSolution)) # print("eigenSolution", eigenSolution) eigenValues = eigenSolution[0] # print("eigenValues", len(eigenValues)) eigenVectors = eigenSolution[1] # print("eigenVectors", type(eigenVectors)) # print("eigenVectors-1", type(eigenVectors[0])) # resized = cv2.resize(eigenVectors[2],(512,512)) # cv2.imshow("eigen",resized) # cv2.waitKey() sort = eigenValues.argsort()[::-1] eigenValues = eigenValues[sort] eigenVectors = eigenVectors[:, sort] # Each eigenvector has the same dimensionality(number # of components) as the original images, and thus # can itself be seen as an image logger.info("shape eigenValues" + str(np.asarray(eigenValues).shape)) logger.info("shape eigenVectors" + str(np.asarray(eigenVectors).shape)) logger.info("shape eigenVectors[0]" + str(np.asarray(eigenVectors[0]).shape)) logger.info("shape eigenVectors[0][0]" + str(np.asarray(eigenVectors[0][0]).shape)) logger.info("value in eigenVectors" + str(eigenValues)) # for i in range(0, 4095): for i in range(0, 361): imageFromVector = np.asarray(eigenVectors[i]) imageFromVector = imageFromVector.reshape((19, 19)) imageFromVector2 = np.array(np.dstack([imageFromVector.real,imageFromVector.imag])) # What I added print("imageFromVector shape", imageFromVector.shape) print("imageFromVector type", type(imageFromVector)) cv2.imshow("imageFromVector", imageFromVector2) # Error in here! cv2.waitKey() # imageFromVector.reshape((64, 64)) file = str(i) + ".jpg" cv2.imwrite(filename=file, img=imageFromVector) # resized = cv2.resize(eigenVectors[0], (512, 512)) # cv2.imshow("eigen", resized) # cv2.waitKey() logger.info("Compute Eigens... Done") return eigenVectors, eigenValues  before I added imageFromVector2 = np.array(np.dstack([imageFromVector.real,imageFromVector.imag])), show an error like this after I added that code, it shown File "E:/PROJECT_FOLDER/PYTHON/PKLBPPT/PCA-with-VJ.py", line 169, in getEigenVectorsAndEigenValues cv2.imshow("imageFromVector", imageFromVector2) cv2.error: D:\Build\OpenCV\opencv-3.2.0\modules\imgcodecs\src\utils.cpp:611: error: (-15) Source image must have 1, 3 or 4 channels in function cvConvertImage  Anyone knows what's wrong with this code? 2017-07-23 22:48:36 -0600 asked a question Error on VTK; nullptr was not declared I had an error when build. This is an error: Scanning dependencies of target opencv_viz_pch_dephelp [ 31%] Building CXX object modules/viz/CMakeFiles/opencv_viz_pch_dephelp.dir/opencv_viz_pch_dephelp.cxx.o In file included from /usr/local/include/vtk-8.1/vtkGenericDataArray.h:72:0, from /usr/local/include/vtk-8.1/vtkAOSDataArrayTemplate.h:35, from /usr/local/include/vtk-8.1/vtkIntArray.h:33, from /usr/local/include/vtk-8.1/vtkCellTypes.h:42, from /usr/local/include/vtk-8.1/vtkPolyData.h:64, from /usr/local/include/vtk-8.1/vtkPolyDataAlgorithm.h:36, from /usr/local/include/vtk-8.1/vtkAppendPolyData.h:35, from /root/opencv/modules/viz/src/precomp.hpp:56, from /root/opencv/build/modules/viz/opencv_viz_pch_dephelp.cxx:1: /usr/local/include/vtk-8.1/vtkGenericDataArrayLookupHelper.h:72:5: warning: identifier ‘nullptr’ is a keyword in C++11 [-Wc++0x-compat] : AssociatedArray{nullptr}, SortedArray(nullptr), ^ /usr/local/include/vtk-8.1/vtkGenericDataArrayLookupHelper.h: In constructor ‘vtkGenericDataArrayLookupHelper::vtkGenericDataArrayLookupHelper()’: /usr/local/include/vtk-8.1/vtkGenericDataArrayLookupHelper.h:72:22: warning: extended initializer lists only available with -std=c++11 or -std=gnu++11 : AssociatedArray{nullptr}, SortedArray(nullptr), ^ /usr/local/include/vtk-8.1/vtkGenericDataArrayLookupHelper.h:72:23: error: ‘nullptr’ was not declared in this scope : AssociatedArray{nullptr}, SortedArray(nullptr), ^ /usr/local/include/vtk-8.1/vtkGenericDataArrayLookupHelper.h:73:15: warning: extended initializer lists only available with -std=c++11 or -std=gnu++11 FirstValue{nullptr}, SortedArraySize{0} ^ /usr/local/include/vtk-8.1/vtkGenericDataArrayLookupHelper.h:73:41: warning: extended initializer lists only available with -std=c++11 or -std=gnu++11 FirstValue{nullptr}, SortedArraySize{0} ^ modules/viz/CMakeFiles/opencv_viz_pch_dephelp.dir/build.make:62: recipe for target 'modules/viz/CMakeFiles/opencv_viz_pch_dephelp.dir/opencv_viz_pch_dephelp.cxx.o' failed make[2]: * [modules/viz/CMakeFiles/opencv_viz_pch_dephelp.dir/opencv_viz_pch_dephelp.cxx.o] Error 1 CMakeFiles/Makefile2:5698: recipe for target 'modules/viz/CMakeFiles/opencv_viz_pch_dephelp.dir/all' failed make[1]: [modules/viz/CMakeFiles/opencv_viz_pch_dephelp.dir/all] Error 2 Makefile:160: recipe for target 'all' failed make: ** [all] Error 2 I had no idea what is wrong. I'm using ubuntu 16.04, VTK 8.0, OpenCV 3.2 (Contrib version too), work on virtualenv