1. 在opencv函數
C++: int floodFill(InputOutputArray image, Point seedPoint, Scalar newVal, Rect* rect=0, Scalar loDiff=Scalar(), Scalar upDiff=Scalar(), int flags=4 )¶
中，flags參數，FLOODFILL_FIXED_RANGE設置到flags是什麼意思？
從seed的4臨域出發，每個點與seed在 [seed-low, seed+up]區間內，那麼這個點就被加到mask裏面。
如果不設置，從seed出發，中心點其臨域的點，臨域的點在[中心點-lo, 中心點+up]範圍內，這個臨域點就被設置、
2. opencv 使用anaconda裏面的python環境， 那麼簡單配置，是無法生成cv2.so, 要仔細看cmake 報告，裏面會說python3 模塊不可用，那麼參考如下：
(py372) silva@silva-HP-Z420-Workstation:/mnt/c/silva/work/build_opencv/opencv4.2/release$ cmake -D CMAKE_BUILD_TYPE=RELEASE -D -DWITH_FFMPEG=ON -D CMAKE_INSTALL_PREFIX=/usr/local -D INSTALL_PYTHON_EXAMPLES=ON -D INSTALL_C_EXAMPLES=OFF -D OPENCV_ENABLE_NONFREE=ON -D OPENCV_EXTRA_MODULES_PATH=/mnt/c/silva/work/build_opencv/opencv_contrib_4.2/modules -D BUILD_EXAMPLES=OFF -D BUILD_PYTHON_SUPPORT=ON -D BUILD_NEW_PYTHON_SUPPORT=ON -DCMAKE_INSTALL_PREFIX=$(python3 -c "import sys; print(sys.prefix)") -DPYTHON3_EXECUTABLE=$(which python3) -DPYTHON3_INCLUDE_DIR=$(python3 -c "from distutils.sysconfig import get_python_inc; print(get_python_inc())") -DPYTHON3_PACKAGES_PATH=$(python3 -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())") -D BUILD_opencv_python3=yes -D PYTHON3_EXECUTABLE=$(which python3) -D PYTHON_INCLUDE_DIR=$(python3 -c "from distutils.sysconfig import get_python_inc; print(get_python_inc())") -D PYTHON_INCLUDE_DIR2=$(python3 -c "from os.path import dirname; from distutils.sysconfig import get_config_h_filename; print(dirname(get_config_h_filename()))") -D PYTHON_LIBRARY=$(python3 -c "from distutils.sysconfig import get_config_var;from os.path import dirname,join ; print(join(dirname(get_config_var('LIBPC')),get_config_var('LDLIBRARY')))") -D PYTHON3_NUMPY_INCLUDE_DIRS=$(python3 -c "import numpy; print(numpy.get_include())") -D PYTHON3_PACKAGES_PATH=$(python3 -c "from distutils.sysconfig import get_python_lib; print(get_python_lib())") -DPYTHON_DEFAULT_EXECUTABLE=$(which python3) ..