From be14a1d47a9602b976eb2a6b34d29722efe4da66 Mon Sep 17 00:00:00 2001
From: Prasadayus <22bcs191@iiitdmj.ac.in>
Date: Tue, 27 Oct 2026 16:44:17 +0530
Subject: [PATCH 1/5] Add Windows ARM64 support for 5.x

---
 .github/workflows/build_wheels_windows.yml | 29 +++++++++++++++-------
 setup.py                                   | 19 +++++++++++---
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/.github/workflows/build_wheels_windows.yml b/.github/workflows/build_wheels_windows.yml
index 81098be0..7b93f743 100644
--- a/.github/workflows/build_wheels_windows.yml
+++ b/.github/workflows/build_wheels_windows.yml
@@ -1,4 +1,4 @@
-name: Windows x86_64
+name: Windows
 
 on:
   pull_request:
@@ -17,12 +17,11 @@ on:
 
 jobs:
   Build:
-    runs-on: windows-2022
+    runs-on: ${{ matrix.platform == 'arm64' && 'windows-11-arm' || 'windows-2022' }}
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.9']
-        platform: [x86, x64]
+        platform: [x86, x64, arm64]
         with_contrib: [0, 1]
         without_gui: [0, 1]
         build_sdist: [0]
@@ -32,6 +31,7 @@ jobs:
       ENABLE_HEADLESS: ${{ matrix.without_gui }}
       ENABLE_CONTRIB: ${{ matrix.with_contrib }}
       OPENCV_TEST_DATA_PATH: ${{ github.workspace }}\opencv_extra\testdata
+      PYTHON_VERSION: ${{ matrix.platform == 'arm64' && '3.11' || '3.9' }}
     steps:
     - name: Cleanup
       shell: bash
@@ -50,17 +50,20 @@ jobs:
       with:
         submodules: false
         fetch-depth: 0
-    - name: Set up Python ${{ matrix.python-version }}
+    - name: Set up Python ${{ env.PYTHON_VERSION }}
       uses: actions/setup-python@v4
       with:
-        python-version: ${{ matrix.python-version }}
+        python-version: ${{ env.PYTHON_VERSION }}
         architecture: ${{ matrix.platform }}
     - name: Setup MSBuild.exe
       uses: microsoft/setup-msbuild@v1.1
+      with:
+        msbuild-architecture: ${{ matrix.platform }}
     - name: Setup NASM
+      if: matrix.platform != 'arm64'
       uses: ilammy/setup-nasm@v1
     - name: Build a package
-      # CMake 3.25 regression fix. See https://stackoverflow.com/questions/74162633/problem-compiling-from-source-opencv-with-mvsc2019-in-64-bit-version
+      # CMake 3.25 regression fix for x86/x64. See https://stackoverflow.com/questions/74162633/problem-compiling-from-source-opencv-with-mvsc2019-in-64-bit-version
       run: |
         python --version
         python -m pip install --upgrade pip
@@ -77,7 +80,7 @@ jobs:
 
   Test:
     needs: [Build]
-    runs-on: windows-2022
+    runs-on: ${{ matrix.platform == 'arm64' && 'windows-11-arm' || 'windows-2022' }}
     defaults:
       run:
         shell: cmd
@@ -85,10 +88,18 @@ jobs:
       fail-fast: false
       matrix:
         python-version: ['3.8', '3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
-        platform: [x86, x64]
+        platform: [x86, x64, arm64]
         with_contrib: [0, 1]
         without_gui: [0, 1]
         build_sdist: [0]
+        exclude:
+          # actions/setup-python does not provide prebuilt arm64 Python before 3.11
+          - platform: arm64
+            python-version: '3.8'
+          - platform: arm64
+            python-version: '3.9'
+          - platform: arm64
+            python-version: '3.10'
     env:
       ACTIONS_ALLOW_UNSECURE_COMMANDS: true
       OPENCV_TEST_DATA_PATH: ${{ github.workspace }}\opencv_extra\testdata
diff --git a/setup.py b/setup.py
index a6f10ffb..a0c7e008 100755
--- a/setup.py
+++ b/setup.py
@@ -101,10 +101,11 @@ def main():
 
     # Files from CMake output to copy to package.
     # Path regexes with forward slashes relative to CMake install dir.
+    # Note: FFMPEG dlls are not yet provided for Windows ARM64
     rearrange_cmake_output_data = {
         "cv2": (
             [r"bin/opencv_videoio_ffmpeg\d{3}%s\.dll" % ("_64" if is64 else "")]
-            if os.name == "nt"
+            if os.name == "nt" and not (platform.machine() == "ARM64" and sys.platform == "win32")
             else []
         )
         +
@@ -157,9 +158,13 @@ def main():
 
     # HACK: Disabled generic assembler for now.
     # Windows 2025 CI environment does not provide suitable assembler or build is broken in OpenCV MLAS.
+    # On ARM64, NOTFOUND also avoids a MinGW toolchain on PATH being misdetected by CMake's ASM probe.
     ci_cmake_generator = (
-        ["-G", "Visual Studio 17 2022",
-         "-DCMAKE_ASM_COMPILER="]
+        ["-G", "Visual Studio 18 2026",
+         "-DCMAKE_ASM_COMPILER=CMAKE_ASM_COMPILER-NOTFOUND"]
+        if os.name == "nt" and platform.machine() == "ARM64"
+        else ["-G", "Visual Studio 17 2022",
+              "-DCMAKE_ASM_COMPILER="]
         if os.name == "nt"
         else ["-G", "Unix Makefiles"]
     )
@@ -198,7 +203,8 @@ def main():
              # Emulated cmake requires following flags to correctly detect
              # target architecture for windows/arm64 build
              "-DOPENCV_WORKAROUND_CMAKE_20989=ON",
-             "-DCMAKE_SYSTEM_PROCESSOR=ARM64"]
+             "-DCMAKE_SYSTEM_PROCESSOR=ARM64",
+             "-DWITH_OPENCL=OFF"]
             if platform.machine() == "ARM64" and sys.platform == "win32"
             # If it is not defined 'linker flags: /machine:X86' on Windows x64
             else ["-DCMAKE_GENERATOR_PLATFORM=x64"] if is64 and sys.platform == "win32"
@@ -264,6 +270,11 @@ def main():
             cmake_args.append("-DWITH_LAPACK=ON")
             cmake_args.append("-DENABLE_PRECOMPILED_HEADERS=OFF")
 
+        if sys.platform.startswith('win') and platform.machine().lower() in ("arm64", "aarch64"):
+            # MSVC does not support OpenCV dispatch features such as NEON_FP16, NEON_BF16 and NEON_DOTPROD. So use NEON as both baseline and dispatch units
+            cmake_args.append("-DCPU_BASELINE=NEON")
+            cmake_args.append("-DCPU_DISPATCH=NEON")
+
     # works via side effect
     RearrangeCMakeOutput(
         rearrange_cmake_output_data, files_outside_package_dir, package_data.keys()

From f66dd1d99ef00f82cc32ded7e8d735cd53ce0c3b Mon Sep 17 00:00:00 2001
From: Prasadayus <22bcs191@iiitdmj.ac.in>
Date: Sun, 8 Nov 2026 14:42:09 +0530
Subject: [PATCH 2/5] remove redundant CPU_BASELINE/CPU_DISPATCH NEON flags on
 win_arm64

---
 setup.py | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/setup.py b/setup.py
index a0c7e008..3b27f804 100755
--- a/setup.py
+++ b/setup.py
@@ -270,11 +270,6 @@ def main():
             cmake_args.append("-DWITH_LAPACK=ON")
             cmake_args.append("-DENABLE_PRECOMPILED_HEADERS=OFF")
 
-        if sys.platform.startswith('win') and platform.machine().lower() in ("arm64", "aarch64"):
-            # MSVC does not support OpenCV dispatch features such as NEON_FP16, NEON_BF16 and NEON_DOTPROD. So use NEON as both baseline and dispatch units
-            cmake_args.append("-DCPU_BASELINE=NEON")
-            cmake_args.append("-DCPU_DISPATCH=NEON")
-
     # works via side effect
     RearrangeCMakeOutput(
         rearrange_cmake_output_data, files_outside_package_dir, package_data.keys()

From 994de5294f6c7ba74fe678805e1dfce885f8951f Mon Sep 17 00:00:00 2001
From: Prasadayus <22bcs191@iiitdmj.ac.in>
Date: Tue, 10 Nov 2026 11:40:36 +0530
Subject: [PATCH 3/5] fix numpy source-build failure on win_arm64

---
 pyproject.toml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pyproject.toml b/pyproject.toml
index ff65d776..e92c1bdf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,8 @@
 [build-system]
 requires = [
   "numpy<2.0; python_version<'3.9'",
-  "numpy==2.0.2; python_version>='3.9' and python_version<'3.13'",
+  "numpy==2.0.2; python_version>='3.9' and python_version<'3.13' and platform_machine!='ARM64'",
+  "numpy>=2.3.0; python_version>='3.9' and python_version<'3.13' and platform_machine=='ARM64'",
   "numpy==2.1.3; python_version=='3.13'",
   "numpy==2.3.2; python_version=='3.14'",
   "packaging",

From 00c17e29b3782a714035ec6328285851b9ff2c7f Mon Sep 17 00:00:00 2001
From: Prasadayus <22bcs191@iiitdmj.ac.in>
Date: Tue, 10 Nov 2026 14:49:16 +0530
Subject: [PATCH 4/5] Bump submodules to 5.1.0

---
 opencv         | 2 +-
 opencv_contrib | 2 +-
 opencv_extra   | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/opencv b/opencv
index 40738fb1..e4f78fbc 160000
--- a/opencv
+++ b/opencv
@@ -1 +1 @@
-Subproject commit 40738fb16ceddb5fb3fea747585f7ce6abb0605b
+Subproject commit e4f78fbcf1a773fbed69e14500e8b734963eb585
diff --git a/opencv_contrib b/opencv_contrib
index 755e5067..b67a8551 160000
--- a/opencv_contrib
+++ b/opencv_contrib
@@ -1 +1 @@
-Subproject commit 755e50675d97db9b7d449d8bd6b09888646f6c6e
+Subproject commit b67a855188a3d683813731010f6d39ac614733a4
diff --git a/opencv_extra b/opencv_extra
index 3becd947..c9608cf1 160000
--- a/opencv_extra
+++ b/opencv_extra
@@ -1 +1 @@
-Subproject commit 3becd947dd6bf6340047de8ca4445a70271e6073
+Subproject commit c9608cf1253af28797bca7550846d13c7db81de7

From 9e11dede198b900055dd2d9d9e6ddd913f548cbf Mon Sep 17 00:00:00 2001
From: Prasadayus <22bcs191@iiitdmj.ac.in>
Date: Wed, 11 Nov 2026 13:33:32 +0530
Subject: [PATCH 5/5] Revert submodule bumps, add WITH_OPENCL comment

---
 opencv         | 2 +-
 opencv_contrib | 2 +-
 opencv_extra   | 2 +-
 setup.py       | 2 ++
 4 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/opencv b/opencv
index e4f78fbc..40738fb1 160000
--- a/opencv
+++ b/opencv
@@ -1 +1 @@
-Subproject commit e4f78fbcf1a773fbed69e14500e8b734963eb585
+Subproject commit 40738fb16ceddb5fb3fea747585f7ce6abb0605b
diff --git a/opencv_contrib b/opencv_contrib
index b67a8551..755e5067 160000
--- a/opencv_contrib
+++ b/opencv_contrib
@@ -1 +1 @@
-Subproject commit b67a855188a3d683813731010f6d39ac614733a4
+Subproject commit 755e50675d97db9b7d449d8bd6b09888646f6c6e
diff --git a/opencv_extra b/opencv_extra
index c9608cf1..3becd947 160000
--- a/opencv_extra
+++ b/opencv_extra
@@ -1 +1 @@
-Subproject commit c9608cf1253af28797bca7550846d13c7db81de7
+Subproject commit 3becd947dd6bf6340047de8ca4445a70271e6073
diff --git a/setup.py b/setup.py
index 3b27f804..59d01195 100755
--- a/setup.py
+++ b/setup.py
@@ -204,6 +204,8 @@ def main():
              # target architecture for windows/arm64 build
              "-DOPENCV_WORKAROUND_CMAKE_20989=ON",
              "-DCMAKE_SYSTEM_PROCESSOR=ARM64",
+             # Adreno GPUs (used on Windows ARM64 devices) produce numerically
+             # divergent OpenCL kernel results.
              "-DWITH_OPENCL=OFF"]
             if platform.machine() == "ARM64" and sys.platform == "win32"
             # If it is not defined 'linker flags: /machine:X86' on Windows x64