树莓派编译安装opencv3 (2019.1.6更新)

1、更新系统

sudo apt-get update  
sudo apt-get upgrade  
sudo rpi-update
#重启系统  
sudo reboot

2、安装依赖库及程序

sudo apt-get -y install build-essential git cmake pkg-config  
sudo apt-get -y install libjpeg8-dev  
sudo apt-get -y install libtiff5-dev  
sudo apt-get -y install libjasper-dev  
sudo apt-get -y install libpng12-dev  
sudo apt-get -y install libavcodec-dev libavformat-dev libswscale-dev libv4l-dev  
sudo apt-get -y install libgtk2.0-dev  
sudo apt-get -y install libsdl2-dev
sudo apt-get -y install libatlas-base-dev gfortran  
sudo apt-get -y install libxvidcore-dev libx264-dev

3、编译安装FFMPEG
之因此要用编译安装是为了确保opencv在cmake时ffmpeg选项为on，这将关系到opencv可否播放视频文件。
先卸载系统默认安装的ffmpeg

sudo apt-get remove ffmpeg

再下载源码并安装最新版ffmpeg

git clone git://source.ffmpeg.org/ffmpeg.git
cd ffmpeg
./configure --enable-shared --disable-static
make -j4
sudo make install
export PKG_CONFIG_PATH="/usr/local/lib/pkgconfig":$PKG_CONFIG_PATH

须要注意一下添加到环境变量PKG_CONFIG_PATH中的地址为ffmpeg编译后存放.pc文件的本地pkgconfig目录。

4、安装更新PYTHON及运行环境

sudo apt-get -y install python2.7-dev python3-dev
curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python get-pip.py
pip install numpy

5、下载、编译安装opencv
在opencv官网下载最新版源码（目前3.X最新版为3.4.5，注意contrib要和opencv的版本要保持一致），要确保opencv和opencv_contrib版本一致，不然会致使编译失败。

wget -O opencv.zip https://github.com/opencv/opencv/archive/3.4.5.zip
wget -O opencv_contrib.zip https://github.com/opencv/opencv_contrib/archive/3.4.5.zip
unzip opencv.zip
unzip opencv_contrib.zip

预编译

cd ~/opencv  
mkdir build  
cd build  
cmake -D CMAKE_BUILD_TYPE=RELEASE \
    -D CMAKE_INSTALL_PREFIX=/usr/local \
    -D INSTALL_PYTHON_EXAMPLES=ON \
    -D OPENCV_EXTRA_MODULES_PATH=~/opencv_contrib-3.4.5/modules \
    -D WITH_FFMPEG=ON \
    -D BUILD_EXAMPLES=ON ..

编译opencv，在树莓派3中建议加上-j4参数，这样编译速度能快一点。

make -j4
sudo make install  
sudo ldconfig

6、部署到PYTHON系统库（此步彷佛能够跳过）
python2.7

ln -s /usr/local/lib/python2.7/dist-packages/cv2/python-2.7/cv2.so /usr/local/lib/python2.7/dist-packages/cv2.so

python 3.0

ln -s /usr/local/lib/python3.5/dist-packages/cv2/python-3.5/cv2.cpython-35m-arm-linux-gnueabihf.so /usr/local/lib/python3.5/dist-packages/cv2.so

7、配置环境
为了使opencv可以正常打开SPI摄像头须要编辑/etc/rc.local
在exit 0以前加入 modprobe bcm2835-v4l2

8、测试
编辑 cameratest.py,添加以下内容，保存并退出。

import cv2
import numpy as np

cap = cv2.VideoCapture(0)
cap.set(3,640) # set Width
cap.set(4,480) # set Height

while(True):
  ret, frame = cap.read()
  frame = cv2.flip(frame, -1) # Flip camera vertically
  gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
  cv2.imshow('frame', frame)
  cv2.imshow('gray', gray)
  k = cv2.waitKey(30)  & 0xff
  if k == 27: # press 'ESC' to quit
    break
cap.release()
cv2.destroyAllWindows()

执行

python cameratest.py