Building OpenCV4 on Linux

^Initial Draft: May 30, 2025^

References

• OpenCV Linux
• CV Tricks (Python)
• CarpeDiem UK (Windows)
• Medium (Windows)

Prerequsites

• Assuming Ubuntu-flavor v24.04+ (LTS)

Qt v6.10+

• Assuming Qt6 installed at /opt/Qt

CMake

• $ cd /opt/Qt/Tools/CMake/bin
• $ ./cmake --version Expect v3.30+

g++ v14.2+

• Test: c++ --version
• Test: gdb --version (using v16.2)

Environment

• $ cd /etc
• $ sudo cp environment environment.###
• $ sudo pico environment
  • Expect: /usr/bin for c++ and friends
  • Expect: git somewhere
  • Add: /opt/Qt/Tools/CMake/bin

Source Code

• Assuming base repository at /data/code/repo
• fork and clone https://github.com/opencv/opencv/tree/4.11.0 or latest (we actually got 4.12)
• fork and clone https://github.com/opencv/opencv_contrib/tree/4.11.0 or latest

CMake Setup

• If new run, `rm -rf /data/code/temp/opencv4[d]/build'
• Run cmake-gui from /opt/Qt/Tools/CMake/bin
• Source: /data/code/repo/opencv
• Build: /data/code/temp/opencv4[d]/build - 'd' for debug
• Deploy later: /data/code/3rdParty/opencv4[d]
• Configure
• Yes if build directory doesn't exist, It Shouldn't!
• Specify Unix Makefiles
• Select Use default native compilers
• Finish

CMake Configuration

• CMAKE

  • Add: CMAKE_MAKE_PROGRAM FILEPATH to /opt/Qt/Tools/CMake/bin/cmake
  • Set: CMAKE_BUILD_TYPE to Release
  • Set: CMAKE_INSTALL_PREFIX to /data/code/3rdParty/opencv4

• BUILD

  • Check: BUILD_DOCS BUILD_EXAMPLES BUILD_OPENJPEG
  • Uncheck: OPENCV_DNN_CUDA
  • Uncheck all except core, imageproc, objdetect, & xobjdetect
  • If NOT Release Build Check: BUILD_WITH_DEBUG_INFO

• OPENCV

  • Set: OPENCV_EXTRA_MODULES_PATH as /data/code/repo/opencv_contrib/modules

• WITH

  • Check: WITH_QT
  • Uncheck: _AVIF _EIGEN _FFMPEG IMGCODEC* _JASPER _JPEG _OPENJPEG _PNG _TESSERACT _TIFF _V4L

• QT

  • Add: QT_QMAKE_EXECUTABLE FILEPATH /opt/Qt/6.10.0/gcc_64/bin/qmake
  • Add: Qt6_DIR PATH /opt/Qt/6.10.0

• INSTALL

• Check: INSTALL_C_EXAMPLES

• Check: INSTALL_TESTS

• Configure

• Generate

Build!

• $ cd /data/code/temp/opencv4[d]/build
• $ make -B
• Make a pot of coffee
• $ make install

Integrate

• Create OpenCV4.pri file in /data/code/repo/Eclipse7

# file: {Eclipse7 repo}/OpenCV4.pri

INCLUDEPATH *= /data/code/3rdParty/opencv4/include/opencv4
LIBS *= -L/data/code/3rdParty/opencv4/libs

LIBS *= -lopencv_core
#LIBS *= -lopencv_highgui
LIBS *= -lopencv_imageproc
LIBS *= -lopencv_objdetect

DISTFILES *= /data/code/3rdParty/opencv4/libs/libopencv_core.so.4.12.0
DISTFILES *= /data/code/3rdParty/opencv4/libs/libopencv_imageproc.so.4.12.0
DISTFILES *= /data/code/3rdParty/opencv4/libs/libopencv_objdetect.so.4.12.0