Install OpenCV (Win + Python) - Module not found error: no module named 'cv2'

Hi, I installed Visual Studio and Microsoft Visual Studios shared Python37_64. Then I downloaded the OpenCV source code to build it by my own via CMake (with Python3). After compiling and building the project file (ALL_BUILD) I also created the install libraries (INSTALL) generated as debug as well as release versions.

Now I opened the Python IDLE and enter ‘import cv2’, which outputs following error message: ModuleNotFoundError: No module named ‘cv2’

Any idea what I have missed?

Selecting Windows SDK version 10.0.18362.0 to target Windows 10.0.19043.
Detected processor: AMD64
Could NOT find PythonInterp (missing: PYTHON_EXECUTABLE) (Required is at least version "2.7")
libjpeg-turbo: VERSION = 2.1.0, BUILD = opencv-4.5.4-libjpeg-turbo
Could NOT find OpenJPEG (minimal suitable version: 2.0, recommended version >= 2.3.1). OpenJPEG will be built from sources
OpenJPEG: VERSION = 2.4.0, BUILD = opencv-4.5.4-openjp2-2.4.0
OpenJPEG libraries will be built from sources: libopenjp2 (version "2.4.0")
found Intel IPP (ICV version): 2020.0.0 [2020.0.0 Gold]
at: C:/opencv_build/3rdparty/ippicv/ippicv_win/icv
found Intel IPP Integration Wrappers sources: 2020.0.0
at: C:/opencv_build/3rdparty/ippicv/ippicv_win/iw
Could not find OpenBLAS include. Turning OpenBLAS_FOUND off
Could not find OpenBLAS lib. Turning OpenBLAS_FOUND off
Could NOT find BLAS (missing: BLAS_LIBRARIES) 
Could NOT find LAPACK (missing: LAPACK_LIBRARIES) 
    Reason given by package: LAPACK could not be found because dependency BLAS could not be found.

VTK is not found. Please set -DVTK_DIR in CMake to VTK build directory, or to VTK install subdirectory with VTKConfig.cmake file
OpenCV Python: during development append to PYTHONPATH: C:/opencv_build/python_loader
Allocator metrics storage type: 'long long'
Registering hook 'INIT_MODULE_SOURCES_opencv_dnn': C:/Users/user/Downloads/opencv/sources/modules/dnn/cmake/hooks/INIT_MODULE_SOURCES_opencv_dnn.cmake
opencv_dnn: filter out cuda4dnn source code
Excluding from source files list: <BUILD>/modules/dnn/layers/layers_common.rvv.cpp
highgui: using builtin backend: WIN32UI

General configuration for OpenCV 4.5.4 =====================================
  Version control:               unknown

    Timestamp:                   2021-11-23T14:36:19Z
    Host:                        Windows 10.0.19043 AMD64
    CMake:                       3.22.0-rc1
    CMake generator:             Visual Studio 16 2019
    CMake build tool:            C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/MSBuild/Current/Bin/MSBuild.exe
    MSVC:                        1929
    Configuration:               Debug Release

  CPU/HW features:
    Baseline:                    SSE SSE2 SSE3
      requested:                 SSE3
    Dispatched code generation:  SSE4_1 SSE4_2 FP16 AVX AVX2 AVX512_SKX
      requested:                 SSE4_1 SSE4_2 AVX FP16 AVX2 AVX512_SKX
      SSE4_1 (17 files):         + SSSE3 SSE4_1
      SSE4_2 (2 files):          + SSSE3 SSE4_1 POPCNT SSE4_2
      FP16 (1 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
      AVX (5 files):             + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
      AVX2 (32 files):           + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2
      AVX512_SKX (8 files):      + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2 AVX_512F AVX512_COMMON AVX512_SKX

    Built as dynamic libs?:      YES
    C++ standard:                11
    C++ Compiler:                C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.29.30133/bin/Hostx64/x64/cl.exe  (ver 19.29.30136.0)
    C++ flags (Release):         /DWIN32 /D_WINDOWS /W4 /GR  /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /Oi  /fp:precise     /EHa /wd4127 /wd4251 /wd4324 /wd4275 /wd4512 /wd4589 /MP  /MD /O2 /Ob2 /DNDEBUG 
    C++ flags (Debug):           /DWIN32 /D_WINDOWS /W4 /GR  /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /Oi  /fp:precise     /EHa /wd4127 /wd4251 /wd4324 /wd4275 /wd4512 /wd4589 /MP  /MDd /Zi /Ob0 /Od /RTC1 
    C Compiler:                  C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.29.30133/bin/Hostx64/x64/cl.exe
    C flags (Release):           /DWIN32 /D_WINDOWS /W3  /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /Oi  /fp:precise     /MP   /MD /O2 /Ob2 /DNDEBUG 
    C flags (Debug):             /DWIN32 /D_WINDOWS /W3  /D _CRT_SECURE_NO_DEPRECATE /D _CRT_NONSTDC_NO_DEPRECATE /D _SCL_SECURE_NO_WARNINGS /Gy /bigobj /Oi  /fp:precise     /MP /MDd /Zi /Ob0 /Od /RTC1 
    Linker flags (Release):      /machine:x64  /INCREMENTAL:NO 
    Linker flags (Debug):        /machine:x64  /debug /INCREMENTAL 
    ccache:                      NO
    Precompiled headers:         YES
    Extra dependencies:
    3rdparty dependencies:

  OpenCV modules:
    To be built:                 calib3d core dnn features2d flann gapi highgui imgcodecs imgproc ml objdetect photo stitching ts video videoio
    Disabled:                    world
    Disabled by dependency:      -
    Unavailable:                 java python2 python3
    Applications:                tests perf_tests apps
    Documentation:               NO
    Non-free algorithms:         NO

  Windows RT support:            NO

  GUI:                           WIN32UI
    Win32 UI:                    YES
    VTK support:                 NO

  Media I/O: 
    ZLib:                        build (ver 1.2.11)
    JPEG:                        build-libjpeg-turbo (ver 2.1.0-62)
    WEBP:                        build (ver encoder: 0x020f)
    PNG:                         build (ver 1.6.37)
    TIFF:                        build (ver 42 - 4.2.0)
    JPEG 2000:                   build (ver 2.4.0)
    OpenEXR:                     build (ver 2.3.0)
    HDR:                         YES
    SUNRASTER:                   YES
    PXM:                         YES
    PFM:                         YES

  Video I/O:
    DC1394:                      NO
    FFMPEG:                      YES (prebuilt binaries)
      avcodec:                   YES (58.134.100)
      avformat:                  YES (58.76.100)
      avutil:                    YES (56.70.100)
      swscale:                   YES (5.9.100)
      avresample:                YES (4.0.0)
    GStreamer:                   NO
    DirectShow:                  YES
    Media Foundation:            YES
      DXVA:                      YES

  Parallel framework:            Concurrency

  Trace:                         YES (with Intel ITT)

  Other third-party libraries:
    Intel IPP:                   2020.0.0 Gold [2020.0.0]
           at:                   C:/opencv_build/3rdparty/ippicv/ippicv_win/icv
    Intel IPP IW:                sources (2020.0.0)
              at:                C:/opencv_build/3rdparty/ippicv/ippicv_win/iw
    Lapack:                      NO
    Eigen:                       NO
    Custom HAL:                  NO
    Protobuf:                    build (3.5.1)

  OpenCL:                        YES (NVD3D11)
    Include path:                C:/Users/user/Downloads/opencv/sources/3rdparty/include/opencl/1.2
    Link libraries:              Dynamic load

  Python (for build):            C:/Program Files (x86)/Microsoft Visual Studio/Shared/Python37_64/python.exe

    ant:                         NO
    JNI:                         NO
    Java wrappers:               NO
    Java tests:                  NO

  Install to:                    C:/opencv_build/install

Configuring done