From 2bf4f5c151eef7e786f5903eff4a010e800bf288 Mon Sep 17 00:00:00 2001
From: Skreg <85214856+shyama7004@users.noreply.github.com>
Date: Tue, 9 Dec 2025 17:01:53 +0530
Subject: [PATCH] Merge pull request #26366 from shyama7004:fix-orb.cpp

Fix ORB inconsistency for masks with values 255 and 1. #26366

### Pull Request Readiness Checklist

The PR fixes : [25974](https://github.com/opencv/opencv/issues/25974)

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
- [ ] 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
---
 modules/features2d/src/orb.cpp       |  8 ++++++--
 modules/features2d/test/test_orb.cpp | 27 +++++++++++++++++++++++++++
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/modules/features2d/src/orb.cpp b/modules/features2d/src/orb.cpp
index b0d32002a1..f970818377 100644
--- a/modules/features2d/src/orb.cpp
+++ b/modules/features2d/src/orb.cpp
@@ -1036,7 +1036,11 @@ void ORB_Impl::detectAndCompute( InputArray _image, InputArray _mask,
     bool useOCL = false;
 #endif
 
-    Mat image = _image.getMat(), mask = _mask.getMat();
+    Mat image = _image.getMat(), mask;
+    if (!_mask.empty())
+    {
+        threshold(_mask, mask, 0, 255, THRESH_BINARY);
+    }
     if( image.type() != CV_8UC1 )
         cvtColor(_image, image, COLOR_BGR2GRAY);
 
@@ -1134,7 +1138,7 @@ void ORB_Impl::detectAndCompute( InputArray _image, InputArray _mask,
             }
 
             copyMakeBorder(currImg, extImg, border, border, border, border,
-                           BORDER_REFLECT_101+BORDER_ISOLATED);
+                           BORDER_REFLECT_101 + BORDER_ISOLATED);
             if (!mask.empty())
                 copyMakeBorder(currMask, extMask, border, border, border, border,
                                BORDER_CONSTANT+BORDER_ISOLATED);
diff --git a/modules/features2d/test/test_orb.cpp b/modules/features2d/test/test_orb.cpp
index 89e2f7d78b..92fe8e9838 100644
--- a/modules/features2d/test/test_orb.cpp
+++ b/modules/features2d/test/test_orb.cpp
@@ -168,4 +168,31 @@ BIGDATA_TEST(Features2D_ORB, regression_opencv_python_537)  // memory usage: ~3
     ASSERT_NO_THROW(orbPtr->detectAndCompute(img, noArray(), kps, fv));
 }
 
+TEST(Features2D_ORB, MaskValue)
+{
+    Mat gray = imread(cvtest::findDataFile("features2d/tsukuba.png"), IMREAD_GRAYSCALE);
+    ASSERT_FALSE(gray.empty());
+
+    cv::Rect roi(gray.cols/4, gray.rows/4, gray.cols/2, gray.rows/2);
+
+    Mat mask255 = Mat::zeros(gray.size(), CV_8UC1);
+    Mat mask1 = Mat::zeros(gray.size(), CV_8UC1);
+    mask255(roi).setTo(255);
+    mask1(roi).setTo(1);
+
+    Ptr<ORB> orb = cv::ORB::create();
+
+    vector<KeyPoint> keypoints_mask255, keypoints_mask1;
+    Mat descriptors_mask255, descriptors_mask1;
+
+    orb->detectAndCompute(gray, mask255, keypoints_mask255, descriptors_mask255, false);
+    orb->detectAndCompute(gray, mask1, keypoints_mask1, descriptors_mask1, false);
+
+    ASSERT_EQ(keypoints_mask255.size(), keypoints_mask1.size())
+        << "Number of keypoints differs between mask values 255 and 1";
+
+    Mat diff = descriptors_mask255 != descriptors_mask1;
+    ASSERT_EQ(countNonZero(diff), 0);
+}
+
 }} // namespace