cmakelists:

cmake_minimum_required(VERSION 3.7)
project(size_function)

set(CMAKE_CXX_STANDARD 11)
find_package(OpenCV REQUIRED)
include_directories(${OpenCV_DIRS})

set(SOURCE_FILES main.cpp)
add_executable(size_function ${SOURCE_FILES})
target_link_libraries(size_function ${OpenCV_LIBS})

程序：

#include <iostream>
#include <opencv2/core/core.hpp