Added support for no-contrib builds and instructions for how to build for linux-arm64 (like Raspberry Pi) #1798

ctacke · 2026-01-25T18:21:56Z

This source chance allows you to build OpenCvSharpExtern to match a stripped-down build of OpenCV. This allows for an app to use OpenCV in an embedded app without having to install the very large opencv-dev package. For example, the stripped-down no-contrib build supporting USB camera streaming and frame capture is only about 16MB for all of the OpenCV bits.

This PR included a readme that explains things a bit, as well as a couple reference scripts to build full and no-contrib binary sets. I have binary release sets for linux-arm64 in my fork.

Copilot

Pull request overview

Adds a configurable “minimal / no-contrib” build path for OpenCvSharpExtern so it can link against stripped-down OpenCV builds (notably for linux-arm64 / Raspberry Pi), plus documentation and helper scripts to build/deploy those binaries.

Changes:

Introduces CMake feature flags (NO_CONTRIB, NO_*) to conditionally compile subsets of OpenCvSharpExtern.
Wraps many module/contrib bindings in preprocessor guards so missing OpenCV modules don’t break linkage.
Adds linux-arm64 build scripts and an embedded build guide, linked from the main README.

Reviewed changes

Copilot reviewed 67 out of 67 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
tool/build-opencvsharp-minimal-arm64.sh	New helper script to build a minimal OpenCV + matching `OpenCvSharpExtern` for linux-arm64 and stage `.so` outputs
tool/build-opencvsharp-arm64.sh	New helper script to build OpenCV + contrib + `OpenCvSharpExtern` for linux-arm64 and stage `.so` outputs
src/CMakeLists.txt	Adds CMake options for disabling module bindings and attempts to translate them into compile definitions
embedded-builds.md	New embedded/ARM build documentation and usage instructions for the scripts/manual builds
README.md	Links to the new embedded build documentation
src/OpenCvSharpExtern/include_opencv.h	Makes OpenCV header inclusion conditional on `NO_*` feature defines
src/OpenCvSharpExtern/std_vector.h	Wraps ML/stitching-related vector bindings to avoid referencing disabled modules
src/OpenCvSharpExtern/aruco.h	Wraps aruco (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/bgsegm.h	Wraps bgsegm (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/img_hash.h	Wraps img_hash (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/line_descriptor.h	Wraps line_descriptor (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/optflow.h	Wraps optflow (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/optflow_motempl.h	Wraps motempl (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/quality.h	Wraps quality (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/tracking.h	Wraps tracking (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/wechat_qrcode.h	Wraps wechat_qrcode (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/xfeatures2d.h	Wraps xfeatures2d (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/ximgproc.h	Wraps ximgproc (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/ximgproc_EdgeBoxes.h	Wraps ximgproc EdgeBoxes bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/ximgproc_EdgeFilter.h	Wraps ximgproc EdgeFilter bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/ximgproc_FastLineDetector.h	Wraps ximgproc FastLineDetector bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/ximgproc_RidgeDetectionFilter.h	Wraps ximgproc RidgeDetectionFilter bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/ximgproc_Segmentation.h	Wraps ximgproc Segmentation bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/ximgproc_StructuredEdgeDetection.h	Wraps ximgproc StructuredEdgeDetection bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/ximgproc_SuperPixel.h	Wraps ximgproc SuperPixel bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/xphoto.h	Wraps xphoto (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/features2d.h	Wraps features2d bindings behind `NO_FEATURES2D`
src/OpenCvSharpExtern/features2d_BOW.h	Wraps features2d BOW bindings behind `NO_FEATURES2D`
src/OpenCvSharpExtern/features2d_DescriptorMatcher.h	Wraps features2d DescriptorMatcher bindings behind `NO_FEATURES2D`
src/OpenCvSharpExtern/features2d_Feature2D.h	Wraps features2d Feature2D bindings behind `NO_FEATURES2D`
src/OpenCvSharpExtern/flann.h	Wraps flann bindings behind `NO_FLANN`
src/OpenCvSharpExtern/flann_IndexParams.h	Wraps flann IndexParams bindings behind `NO_FLANN`
src/OpenCvSharpExtern/dnn.h	Wraps dnn bindings behind `NO_DNN`
src/OpenCvSharpExtern/dnn_Net.h	Wraps dnn Net bindings behind `NO_DNN`
src/OpenCvSharpExtern/ml.h	Wraps ml bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_ANN_MLP.h	Wraps ANN_MLP bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_Boost.h	Wraps Boost bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_DTrees.h	Wraps DTrees bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_EM.h	Wraps EM bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_KNearest.h	Wraps KNearest bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_LogisticRegression.h	Wraps LogisticRegression bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_NormalBayesClassifier.h	Wraps NormalBayesClassifier bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_RTrees.h	Wraps RTrees bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_SVM.h	Wraps SVM bindings behind `NO_ML`
src/OpenCvSharpExtern/ml_StatModel.h	Wraps StatModel bindings behind `NO_ML`
src/OpenCvSharpExtern/objdetect.h	Wraps objdetect bindings behind `NO_OBJDETECT`
src/OpenCvSharpExtern/objdetect_HOGDescriptor.h	Wraps HOGDescriptor bindings behind `NO_OBJDETECT`
src/OpenCvSharpExtern/objdetect_QRCodeDetector.h	Wraps QRCodeDetector bindings behind `NO_OBJDETECT`
src/OpenCvSharpExtern/photo.h	Wraps photo bindings behind `NO_PHOTO`
src/OpenCvSharpExtern/photo_HDR.h	Wraps HDR helpers behind `NO_PHOTO`
src/OpenCvSharpExtern/photo_Tonemap.h	Wraps tonemap helpers behind `NO_PHOTO`
src/OpenCvSharpExtern/stitching.h	Wraps stitching bindings behind `NO_STITCHING`
src/OpenCvSharpExtern/stitching_detail_Matchers.h	Wraps stitching detail matcher bindings behind `NO_STITCHING`
src/OpenCvSharpExtern/calib3d.h	Wraps calib3d bindings behind `NO_CALIB3D`
src/OpenCvSharpExtern/calib3d_fisheye.h	Wraps fisheye helpers behind `NO_CALIB3D`
src/OpenCvSharpExtern/calib3d_StereoMatcher.h	Wraps StereoMatcher helpers behind `NO_CALIB3D`
src/OpenCvSharpExtern/video.h	Wraps video includes behind `NO_VIDEO`
src/OpenCvSharpExtern/video_tracking.h	Wraps video tracking bindings behind `NO_VIDEO`
src/OpenCvSharpExtern/video_background_segm.h	Wraps video background segmentation bindings behind `NO_VIDEO`
src/OpenCvSharpExtern/text.h	Wraps text (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/text_TextDetector.h	Wraps TextDetector (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/superres.h	Wraps superres (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/shape_ShapeDistanceExtractor.h	Wraps shape (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/dnn_superres.h	Wraps dnn_superres (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/face_Facemark.h	Wraps face facemark (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/face_FaceRecognizer.h	Wraps face recognizer (contrib) bindings behind `NO_CONTRIB`
src/OpenCvSharpExtern/barcode.h	Wraps barcode bindings behind `NO_BARCODE`

Comments suppressed due to low confidence (1)

src/OpenCvSharpExtern/superres.h:354

The #endif comment doesn’t match the opening condition (#ifndef _WINRT_DLL). This is minor, but it makes the preprocessor nesting harder to follow; consider changing it to reflect the actual condition being closed (e.g., “!_WINRT_DLL”).

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

Copilot · 2026-01-25T18:33:42Z

tool/build-opencvsharp-arm64.sh

+ROOT_DIR=$(pwd)
+INSTALL_PREFIX="$ROOT_DIR/opencv-install"
+RUNTIME_DIR="$ROOT_DIR/runtimes/linux-arm64/native"
+


This script assumes it’s run from a directory that contains opencv/, opencv_contrib/, and opencvsharp/ as children because it uses ROOT_DIR=$(pwd). To make it harder to run from the wrong working directory, consider deriving paths from the script location and/or validating that the expected directories exist before continuing.

Copilot · 2026-01-25T18:33:43Z

embedded-builds.md

+
+Using a Raspberry Pi with a 64-bit build of Debian Trixie (Lite is fine)
+
+If you want a build of OpenCV that minimizes the on-disk footprint, you can turn off features (i.e. omit them from the build) for a custom OpenCV build.  If you do this, you must also build a custom OpenCvExtern library that matches your configuration.


The text refers to building a custom OpenCvExtern library, but the native wrapper in this repo is named OpenCvSharpExtern. This is likely to confuse readers following the instructions.

Suggested change

If you want a build of OpenCV that minimizes the on-disk footprint, you can turn off features (i.e. omit them from the build) for a custom OpenCV build. If you do this, you must also build a custom OpenCvExtern library that matches your configuration.

If you want a build of OpenCV that minimizes the on-disk footprint, you can turn off features (i.e. omit them from the build) for a custom OpenCV build. If you do this, you must also build a custom OpenCvSharpExtern library that matches your configuration.

Copilot · 2026-01-25T18:33:43Z

embedded-builds.md

+
+You can build a subset, but it takes some work. The way Linux libraries link, you have to handle all of the dependencies. You can't simply rebuild OpenCV with fewer features and have it work. OpenCvSharpExtern is linked to the endpoints of all of the features in OpenCV, so if some of them are missing, loading `libOpenCvSharpExtern.so` will fail even if you aren't using the missing features. You must rebuild both, and the original OpenCVSharpExtern is not created to make this friendly.
+
+This fork attempts to address that (and maybe it will get merged back in - I'll certainly PR it).


This section is written as if it’s documentation in a personal fork (e.g., “This fork attempts to address that…”). If this is being merged upstream, the wording should be updated to refer to this repository/PR rather than a fork, otherwise the instructions become misleading.

Suggested change

This fork attempts to address that (and maybe it will get merged back in - I'll certainly PR it).

This repository attempts to address that by providing better support for minimal, configurable builds.

Copilot · 2026-01-25T18:33:43Z

embedded-builds.md

+cd ~
+git clone https://github.com/opencv/opencv.git
+git clone https://github.com/opencv/opencv_contrib.git  # only needed for full build
+git clone https://github.com/ctacke/opencvsharp.git


This guide currently instructs users to clone https://github.com/ctacke/opencvsharp.git. If this documentation is intended for the upstream repo, this should point to the canonical repository (e.g., https://github.com/shimat/opencvsharp.git) or use a relative reference, otherwise readers will end up on the wrong codebase.

Suggested change

git clone https://github.com/ctacke/opencvsharp.git

git clone https://github.com/shimat/opencvsharp.git

Copilot · 2026-01-25T18:33:43Z

embedded-builds.md

+First, clone the code. It's important that you clone this fork, not the original, so that the proper defines are in the code.
+
+```bash
+cd ~
+git clone https://github.com/ctacke/opencvsharp.git


Same issue as earlier in the doc: this section tells readers to clone https://github.com/ctacke/opencvsharp.git. After merging upstream, the instructions should reference this repository (or clearly explain why a fork is required).

Suggested change

First, clone the code. It's important that you clone this fork, not the original, so that the proper defines are in the code.

```bash

cd ~

git clone https://github.com/ctacke/opencvsharp.git

First, clone the OpenCvSharp repository that contains the matching build configuration.

```bash

cd ~

git clone https://github.com/shimat/opencvsharp.git

Copilot · 2026-01-25T18:33:44Z

src/OpenCvSharpExtern/quality.h

+#endif // _WINRT_DLL
+#endif // NO_CONTRIB


The #endif comment doesn’t match the opening condition (#ifndef _WINRT_DLL). This is minor, but it makes the preprocessor nesting harder to follow; consider changing it to reflect the actual condition being closed (e.g., “!_WINRT_DLL”).

Copilot · 2026-01-25T18:33:45Z

src/CMakeLists.txt

+    add_compile_definitions(NO_CONTRIB)
+endif()
+if(NO_STITCHING)
+    add_compile_definitions(NO_STITCHING)
+endif()
+if(NO_CALIB3D)
+    add_compile_definitions(NO_CALIB3D)
+endif()
+if(NO_VIDEO)
+    add_compile_definitions(NO_VIDEO)
+endif()
+if(NO_FEATURES2D)
+    add_compile_definitions(NO_FEATURES2D)
+endif()
+if(NO_FLANN)
+    add_compile_definitions(NO_FLANN)
+endif()
+if(NO_DNN)
+    add_compile_definitions(NO_DNN)
+endif()
+if(NO_ML)
+    add_compile_definitions(NO_ML)
+endif()
+if(NO_OBJDETECT)
+    add_compile_definitions(NO_OBJDETECT)
+endif()
+if(NO_PHOTO)
+    add_compile_definitions(NO_PHOTO)
+endif()
+if(NO_BARCODE)
+    add_compile_definitions(NO_BARCODE)


add_compile_definitions() requires newer CMake (>=3.12), but this project declares cmake_minimum_required(VERSION 3.0), so configuring with older CMake will fail. Either bump the minimum required CMake version accordingly, or replace these with a CMake-3.0-compatible approach (e.g., add_definitions(-D...) or target_compile_definitions() on the OpenCvSharpExtern target).

Suggested change

add_compile_definitions(NO_CONTRIB)

endif()

if(NO_STITCHING)

add_compile_definitions(NO_STITCHING)

endif()

if(NO_CALIB3D)

add_compile_definitions(NO_CALIB3D)

endif()

if(NO_VIDEO)

add_compile_definitions(NO_VIDEO)

endif()

if(NO_FEATURES2D)

add_compile_definitions(NO_FEATURES2D)

endif()

if(NO_FLANN)

add_compile_definitions(NO_FLANN)

endif()

if(NO_DNN)

add_compile_definitions(NO_DNN)

endif()

if(NO_ML)

add_compile_definitions(NO_ML)

endif()

if(NO_OBJDETECT)

add_compile_definitions(NO_OBJDETECT)

endif()

if(NO_PHOTO)

add_compile_definitions(NO_PHOTO)

endif()

if(NO_BARCODE)

add_compile_definitions(NO_BARCODE)

add_definitions(-DNO_CONTRIB)

endif()

if(NO_STITCHING)

add_definitions(-DNO_STITCHING)

endif()

if(NO_CALIB3D)

add_definitions(-DNO_CALIB3D)

endif()

if(NO_VIDEO)

add_definitions(-DNO_VIDEO)

endif()

if(NO_FEATURES2D)

add_definitions(-DNO_FEATURES2D)

endif()

if(NO_FLANN)

add_definitions(-DNO_FLANN)

endif()

if(NO_DNN)

add_definitions(-DNO_DNN)

endif()

if(NO_ML)

add_definitions(-DNO_ML)

endif()

if(NO_OBJDETECT)

add_definitions(-DNO_OBJDETECT)

endif()

if(NO_PHOTO)

add_definitions(-DNO_PHOTO)

endif()

if(NO_BARCODE)

add_definitions(-DNO_BARCODE)

Copilot · 2026-01-25T18:33:45Z

src/OpenCvSharpExtern/text_TextDetector.h

+#endif // _WINRT_DLL
+#endif // NO_CONTRIB


The #endif comment doesn’t match the opening condition (#ifndef _WINRT_DLL). This is minor, but it makes the preprocessor nesting harder to follow; consider changing it to reflect the actual condition being closed (e.g., “!_WINRT_DLL”).

Copilot · 2026-01-25T18:33:45Z

src/OpenCvSharpExtern/face_FaceRecognizer.h

+#pragma endregion

-#endif
+#endif // _WINRT_DLL


The #endif comment doesn’t match the opening condition (#ifndef _WINRT_DLL). This is minor, but it makes the preprocessor nesting harder to follow; consider changing it to reflect the actual condition being closed (e.g., “!_WINRT_DLL”).

Suggested change

#endif // _WINRT_DLL

#endif // !_WINRT_DLL

Copilot · 2026-01-25T18:33:46Z

tool/build-opencvsharp-minimal-arm64.sh

+ROOT_DIR=$(pwd)
+INSTALL_PREFIX="/opt/opencv-nocontrib"
+RUNTIME_DIR="$ROOT_DIR/runtimes/linux-arm64/native"
+


This script assumes it’s run from a directory that contains opencv/, opencv_contrib/, and opencvsharp/ as children because it uses ROOT_DIR=$(pwd). To make it harder to run from the wrong working directory, consider deriving paths from the script location and/or validating that the expected directories exist before continuing.

ctacke added 7 commits January 20, 2026 08:44

feat: add no-contrib support

0ff08da

fix: remove stitching from NO_CONRIB

7a09897

fix: working on feature separation in OpenCvExtern

5610f58

optional barcode

7bd0b8b

fix: updated makefile for individual options

6220c4c

fix: add guards in std_vector

90b3700

chore: updated docs for minimal build

9b07050

Copilot AI review requested due to automatic review settings January 25, 2026 18:21

Copilot started reviewing on behalf of ctacke January 25, 2026 18:22 View session

Copilot AI reviewed Jan 25, 2026

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Added support for no-contrib builds and instructions for how to build for linux-arm64 (like Raspberry Pi) #1798

Added support for no-contrib builds and instructions for how to build for linux-arm64 (like Raspberry Pi) #1798

Uh oh!

ctacke commented Jan 25, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Copilot AI Jan 25, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant


		Using a Raspberry Pi with a 64-bit build of Debian Trixie (Lite is fine)

		If you want a build of OpenCV that minimizes the on-disk footprint, you can turn off features (i.e. omit them from the build) for a custom OpenCV build. If you do this, you must also build a custom OpenCvExtern library that matches your configuration.


		You can build a subset, but it takes some work. The way Linux libraries link, you have to handle all of the dependencies. You can't simply rebuild OpenCV with fewer features and have it work. OpenCvSharpExtern is linked to the endpoints of all of the features in OpenCV, so if some of them are missing, loading `libOpenCvSharpExtern.so` will fail even if you aren't using the missing features. You must rebuild both, and the original OpenCVSharpExtern is not created to make this friendly.

		This fork attempts to address that (and maybe it will get merged back in - I'll certainly PR it).

	This fork attempts to address that (and maybe it will get merged back in - I'll certainly PR it).
	This repository attempts to address that by providing better support for minimal, configurable builds.

	git clone https://github.com/ctacke/opencvsharp.git
	git clone https://github.com/shimat/opencvsharp.git

Uh oh!

Added support for no-contrib builds and instructions for how to build for linux-arm64 (like Raspberry Pi) #1798

Are you sure you want to change the base?

Added support for no-contrib builds and instructions for how to build for linux-arm64 (like Raspberry Pi) #1798

Uh oh!

Conversation

ctacke commented Jan 25, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Copilot AI Jan 25, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant