From 02466fac6bad93a5934e27c79d5cffd0bbcac7ec Mon Sep 17 00:00:00 2001
From: Lazizbek Ergashev <lazerg2@gmail.com>
Date: Mon, 3 Aug 2026 13:13:36 +0500
Subject: [PATCH] features: fix MSER discarding stable regions via minDiversity
 (#29652)

---
 modules/features/src/mser.cpp       |  2 +-
 modules/features/test/test_mser.cpp | 28 ++++++++++------------------
 2 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/modules/features/src/mser.cpp b/modules/features/src/mser.cpp
index 9350f3dfca..10913ca1a1 100644
--- a/modules/features/src/mser.cpp
+++ b/modules/features/src/mser.cpp
@@ -264,7 +264,7 @@ public:
             if( checked )
                 return;
             checked = true;
-            if( size < wp.p.minArea || size > wp.p.maxArea || var < wp.p.minDiversity || var > wp.p.maxVariation )
+            if( size < wp.p.minArea || size > wp.p.maxArea || var < 0.f || var > wp.p.maxVariation )
                 return;
             if( child_ )
             {
diff --git a/modules/features/test/test_mser.cpp b/modules/features/test/test_mser.cpp
index 9f7e35dc41..5a4980d015 100644
--- a/modules/features/test/test_mser.cpp
+++ b/modules/features/test/test_mser.cpp
@@ -182,27 +182,19 @@ TEST(Features2d_MSER, history_update_regression)
 }
 
 
-TEST(Features2d_MSER, bug_5630)
+TEST(Features2d_MSER, default_params_regression_29652)
 {
-    String dataPath = cvtest::TS::ptr()->get_data_path() + "mser/";
-    Mat img = imread(dataPath + "mser_test.png", IMREAD_GRAYSCALE);
-    Ptr<MSER> mser = MSER::create(1, 1);
-    vector<vector<Point> > mserContours;
-    vector<Rect> boxRects;
+    Mat img = Mat::zeros(200, 200, CV_8U);
+    rectangle(img, Point(40, 40), Point(160, 160), Scalar(255), -1);
+    circle(img, Point(100, 100), 30, Scalar(0), -1);
 
-    // set min diversity and run detection
-    mser->setMinDiversity(0.1);
-    mser->detectRegions(img, mserContours, boxRects);
-    size_t originalNumberOfContours = mserContours.size();
-
-    // increase min diversity and run detection again
-    mser->setMinDiversity(0.2);
-    mser->detectRegions(img, mserContours, boxRects);
-    size_t newNumberOfContours = mserContours.size();
-
-    // there should be fewer regions detected with a higher min diversity
-    ASSERT_LT(newNumberOfContours, originalNumberOfContours);
+    Ptr<MSER> mser = MSER::create();
+    vector<vector<Point> > regions;
+    vector<Rect> bboxes;
+    mser->detectRegions(img, regions, bboxes);
 
+    ASSERT_FALSE(regions.empty());
+    ASSERT_EQ(regions.size(), bboxes.size());
 }
 
 }} // namespace