ubuntu20 默认安装opencv4 ,如果需要3的话就需要安安装一下
#安装依赖
sudo apt install cmake build-essential libgtk2.0-dev libavcodec-dev libavformat-dev libjpeg-dev libswscale-dev libtiff5-dev libgtk2.0-dev pkg-config -y
#下载源码
https://gitee.com/zsy26226/opencv/tags #选择3.4.16
#解压后进入源码目录
mkdir build
cd build
cmake -D CMAKE_BUILD_TYPE=Release -D CMAKE_INSTALL_PREFIX=/usr/local ..
make -j4
sudo make install
sudo sh -c "echo \"include /usr/local/lib\" >> /etc/ld.so.conf"
sudo ldconfig #刷新库链接配置
#添加环境变量
sudo sh -c "echo \"PKG_CONFIG_PATH=\\\$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig\" >> /etc/bash.bashrc "
sudo sh -c "echo \"export PKG_CONFIG_PATH\" >> /etc/bash.bashrc "
source /etc/bash.bashrc
#检验是否安装成功
pkg-config opencv --modversion