dlpack Python support for cuda_GpuMat and cuda_GpuMatND by dkurt · Pull Request #27581 · opencv/opencv

dkurt · 2025-07-26T19:31:40Z

Pull Request Readiness Checklist

resolves #16295

docker run --gpus 0 -v ~/opencv:/opencv -v ~/opencv_contrib:/opencv_contrib -it nvidia/cuda:12.8.1-cudnn-devel-ubuntu22.04
apt-get update && apt-get install -y cmake python3-dev python3-pip python3-venv &&
python3 -m venv .venv &&
source .venv/bin/activate &&
pip install -U pip &&
pip install -U numpy &&
pip install torch --index-url https://download.pytorch.org/whl/cu128 &&
cmake \
    -DWITH_OPENCL=OFF \
    -DCMAKE_BUILD_TYPE=Release \
    -DBUILD_DOCS=OFF \
    -DWITH_CUDA=ON \
    -DOPENCV_DNN_CUDA=ON \
    -DOPENCV_EXTRA_MODULES_PATH=/opencv_contrib/modules \
    -DBUILD_LIST=ts,cudev,python3 \
    -S /opencv -B /opencv_build &&
cmake --build /opencv_build -j16
export PYTHONPATH=/opencv_build/lib/python3/:$PYTHONPATH

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

I agree to contribute to the project under Apache 2 License.
To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
The PR is proposed to the proper branch
There is a reference to the original bug report and related work
There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
The feature is well documented and sample code can be built with the project CMake

asmorkalov · 2025-07-28T05:53:34Z

DLpack available as deb package on Ubuntu. It'll be great to support external instances via find_package too just i case of compatibility issues.

asmorkalov · 2025-07-28T05:53:43Z

cc @cudawarped

asmorkalov · 2025-08-04T05:17:31Z

Windows build warnings:

C:/GHA-OCV-2/_work/opencv/opencv/opencv/modules/core/misc/python/pyopencv_cuda.hpp(44): warning C4267: 'argument': conversion from 'size_t' to 'int', possible loss of data

C:/GHA-OCV-2/_work/opencv/opencv/opencv/modules/core/misc/python/pyopencv_cuda.hpp(60): warning C4267: 'argument': conversion from 'size_t' to 'int', possible loss of data

C:/GHA-OCV-2/_work/opencv/opencv/opencv/modules/core/misc/python/pyopencv_cuda.hpp(92): warning C4244: 'argument': conversion from 'int64_t' to 'int', possible loss of data

C:/GHA-OCV-2/_work/opencv/opencv/opencv/modules/core/misc/python/pyopencv_cuda.hpp(98): warning C4244: 'argument': conversion from 'int64_t' to 'int', possible loss of data

C:/GHA-OCV-2/_work/opencv/opencv/opencv/modules/core/misc/python/pyopencv_cuda.hpp(97): warning C4244: 'argument': conversion from 'int64_t' to 'int', possible loss of data

C:/GHA-OCV-2/_work/opencv/opencv/opencv/modules/core/misc/python/pyopencv_cuda.hpp(119): warning C4244: 'argument': conversion from 'int64_t' to 'int', possible loss of data

C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.29.30133\include\xmemory(681): warning C4244: 'initializing': conversion from 'value_t' to '_Objty', possible loss of data

asmorkalov · 2025-08-12T15:42:38Z

@dkurt Thanks a lot for the contribution! Several questions and proposals:

ls dlpack designed to work with regular CPU memory? Do we need cv::Mat/ndarray integration?
Cuda is not enabled in default opencv-python builds. What is expected behaviour?
Imho it make sense to move the test to regular test suite from CUDA.

dkurt · 2025-08-12T15:52:15Z

ls dlpack designed to work with regular CPU memory? Do we need cv::Mat/ndarray integration?

Yes, but as we already work with OpenCV memory as numpy array, we can use numpy's dlpack.

Cuda is not enabled in default opencv-python builds. What is expected behaviour?

CUDA is required so actual for build from source.

Imho it make sense to move the test to regular test suite from CUDA.

Do you mean opencv_contrib?

asmorkalov · 2025-08-14T06:13:45Z

Do you mean opencv_contrib?

No. test_cuda.py is not triggered by CI now.

dkurt · 2025-08-14T06:21:22Z

@asmorkalov I see only dnn tests here: https://github.com/opencv/opencv/actions/runs/16773287951/job/47493324938?pr=27581 . Shall I extend the test scope to include Python tests to CUDA runner?

asmorkalov · 2025-08-15T12:14:38Z

Most probably you need to push something to refresh CI branch.

### Pull Request Readiness Checklist resolves opencv#16295 ``` docker run --gpus 0 -v ~/opencv:/opencv -v ~/opencv_contrib:/opencv_contrib -it nvidia/cuda:12.8.1-cudnn-devel-ubuntu22.04 apt-get update && apt-get install -y cmake python3-dev python3-pip python3-venv && python3 -m venv .venv && source .venv/bin/activate && pip install -U pip && pip install -U numpy && pip install torch --index-url https://download.pytorch.org/whl/cu128 && cmake \ -DWITH_OPENCL=OFF \ -DCMAKE_BUILD_TYPE=Release \ -DBUILD_DOCS=OFF \ -DWITH_CUDA=ON \ -DOPENCV_DNN_CUDA=ON \ -DOPENCV_EXTRA_MODULES_PATH=/opencv_contrib/modules \ -DBUILD_LIST=ts,cudev,python3 \ -S /opencv -B /opencv_build && cmake --build /opencv_build -j16 export PYTHONPATH=/opencv_build/lib/python3/:$PYTHONPATH ``` See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [x] I agree to contribute to the project under Apache 2 License. - [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV - [x] The PR is proposed to the proper branch - [x] There is a reference to the original bug report and related work - [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable Patch to opencv_extra has the same branch name. - [x] The feature is well documented and sample code can be built with the project CMake

opencv-alalek · 2025-09-21T19:37:27Z

Win32 warnings:

C:/build/precommit_windows32/4.x/opencv/modules/core/misc/python/pyopencv_cuda.hpp(116): warning C4244: 'argument': conversion from 'int64_t' to 'std::size_t', possible loss of data (compiling source file C:\build\precommit_windows32\4.x\opencv\modules\python\src2\cv2.cpp) [C:\build\precommit_windows32\build\modules\python3\opencv_python3.vcxproj]
C:/build/precommit_windows32/4.x/opencv/modules/core/misc/python/pyopencv_cuda.hpp(143): warning C4244: '=': conversion from 'int64_t' to 'unsigned int', possible loss of data (compiling source file C:\build\precommit_windows32\4.x\opencv\modules\python\src2\cv2.cpp) [C:\build\precommit_windows32\build\modules\python3\opencv_python3.vcxproj]

Add 5.x types for DLPack. Keep uint32/int64/uint64 data type for conversion to Numpy. More types support for GpuMat::convertTo #27779 ### Pull Request Readiness Checklist **Merge with contrib**: opencv/opencv_contrib#4000 related: #27581 See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request - [x] I agree to contribute to the project under Apache 2 License. - [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV - [x] The PR is proposed to the proper branch - [x] There is a reference to the original bug report and related work - [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable Patch to opencv_extra has the same branch name. - [x] The feature is well documented and sample code can be built with the project CMake

dkurt added 4 commits July 26, 2025 20:13

Add __dlpack__ dummy method to cuda_GpuMat

594b0e3

dlpack 3rdparty source

d656926

Minimal example with Pytorch

2c70626

Skip test

b367a92

dkurt added the category: python bindings label Jul 26, 2025

asmorkalov self-requested a review July 28, 2025 05:50

asmorkalov added this to the 4.13.0 milestone Jul 28, 2025

asmorkalov added the category: gpu/cuda (contrib) OpenCV 4.0+: moved to opencv_contrib label Jul 28, 2025

asmorkalov self-assigned this Jul 28, 2025

dkurt added 3 commits July 28, 2025 21:13

GpuMatND

fae5ee4

initial from_dlpack

1a207ce

Move common code to pyopencv_core

1419307

dkurt added 2 commits August 4, 2025 17:49

Try detect system dlpack. Check requested device in __dlpack__

781e8b7

Consider copy argument for from_dlpack

52af6a5

dkurt force-pushed the d.kuryaev/dlpack branch from cb28a92 to 52af6a5 Compare August 5, 2025 09:52

dkurt changed the title ~~dlpack Python support for cuda_GpuMat~~ dlpack Python support for cuda_GpuMat and cuda_GpuMatND Aug 7, 2025

dkurt marked this pull request as ready for review August 7, 2025 10:58

dkurt mentioned this pull request Aug 7, 2025

Any intention to add interoperability with DLPACK or mpi4py? #16295

Closed

kmaehashi mentioned this pull request Aug 7, 2025

Document OpenCV interoperability cupy/cupy#7604

Open

int cast warning

052b79f

dkurt force-pushed the d.kuryaev/dlpack branch from c88371f to 052b79f Compare August 15, 2025 12:16

asmorkalov approved these changes Aug 20, 2025

View reviewed changes

asmorkalov added the feature label Aug 20, 2025

asmorkalov merged commit ba19416 into opencv:4.x Aug 20, 2025
23 of 28 checks passed

asmorkalov mentioned this pull request Aug 20, 2025

5.x merge 4.x #27694

Closed

asmorkalov mentioned this pull request Aug 27, 2025

5.x merge 4.x #27719

Merged

dkurt mentioned this pull request Sep 14, 2025

Add 5.x types for DLPack. Keep uint32/int64/uint64 data type for conversion to Numpy. More types support for GpuMat::convertTo #27779

Merged

6 tasks

asmorkalov mentioned this pull request Oct 2, 2025

Warning fixes in DLpack integration on Win32 #27861

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dlpack Python support for cuda_GpuMat and cuda_GpuMatND#27581

dlpack Python support for cuda_GpuMat and cuda_GpuMatND#27581
asmorkalov merged 10 commits intoopencv:4.xfrom
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