different interpolation by double image (#23124)

* different interpolation by double image

* fixing scaling mapping

* fixing a test

* added an option to enable previous interpolation

* added doxygen entries for the new parameter

* ASSERT_TRUE -> ASSERT_EQ

* changed log message when using old upscale mode

modules/features2d/test/test_descriptors_regression.impl.hpp

@@ -7,6 +7,34 @@ namespace opencv_test { namespace {
 /****************************************************************************************\
 *                     Regression tests for descriptor extractors.                        *
 \****************************************************************************************/
+static void double_image(Mat& src, Mat& dst) {
+
+    dst.create(Size(src.cols*2, src.rows*2), src.type());
+
+    Mat H = Mat::zeros(2, 3, CV_32F);
+    H.at<float>(0, 0) = 0.5f;
+    H.at<float>(1, 1) = 0.5f;
+    cv::warpAffine(src, dst, H, dst.size(), INTER_LINEAR | WARP_INVERSE_MAP, BORDER_REFLECT);
+
+}
+
+static Mat prepare_img(bool rows_indexed) {
+    int rows = 5;
+    int columns = 5;
+    Mat img(rows, columns, CV_32F);
+
+    for (int i = 0; i < rows; i++) {
+        for (int j = 0; j < columns; j++) {
+            if (rows_indexed) {
+                img.at<float>(i, j) = (float)i;
+            } else {
+                img.at<float>(i, j) = (float)j;
+            }
+        }
+    }
+    return img;
+}
+
 static void writeMatInBin( const Mat& mat, const string& filename )
 {
     FILE* f = fopen( filename.c_str(), "wb");
@@ -145,6 +173,25 @@ protected:
             ts->set_failed_test_info( cvtest::TS::FAIL_INVALID_TEST_DATA );
         }
 
+        image = prepare_img(false);
+        Mat dbl;
+        try
+        {
+            double_image(image, dbl);
+
+            Mat downsized_back(dbl.rows/2, dbl.cols/2, CV_32F);
+            resize(dbl, downsized_back, Size(dbl.cols/2, dbl.rows/2), 0, 0, INTER_NEAREST);
+
+            cv::Mat diff = (image != downsized_back);
+            ASSERT_EQ(0, cv::norm(image, downsized_back, NORM_INF));
+        }
+        catch(...)
+        {
+            ts->printf( cvtest::TS::LOG, "double_image() must not generate exception (1).\n");
+            ts->printf( cvtest::TS::LOG, "double_image() when downsized back by NEAREST must generate the same original image (1).\n");
+            ts->set_failed_test_info( cvtest::TS::FAIL_INVALID_TEST_DATA );
+        }
+
         // Several images.
         vector<Mat> images;
         vector<vector<KeyPoint> > keypointsCollection;

modules/features2d/test/test_detectors_invariance.cpp

@@ -37,7 +37,7 @@ INSTANTIATE_TEST_CASE_P(AKAZE_DESCRIPTOR_KAZE, DetectorRotationInvariance,
  */
 
 INSTANTIATE_TEST_CASE_P(SIFT, DetectorScaleInvariance,
-                        Value(IMAGE_BIKES, SIFT::create(0, 3, 0.09), 0.65f, 0.98f));
+                        Value(IMAGE_BIKES, SIFT::create(0, 3, 0.09), 0.60f, 0.98f));
 
 INSTANTIATE_TEST_CASE_P(BRISK, DetectorScaleInvariance,
                         Value(IMAGE_BIKES, BRISK::create(), 0.08f, 0.49f));

modules/features2d/test/test_detectors_invariance.impl.hpp

@@ -25,7 +25,6 @@ void matchKeyPoints(const vector<KeyPoint>& keypoints0, const Mat& H,
         perspectiveTransform(Mat(points0), points0t, H);
 
     matches.clear();
-    vector<uchar> usedMask(keypoints1.size(), 0);
     for(int i0 = 0; i0 < static_cast<int>(keypoints0.size()); i0++)
     {
         int nearestPointIndex = -1;
@@ -33,8 +32,6 @@ void matchKeyPoints(const vector<KeyPoint>& keypoints0, const Mat& H,
         const float r0 =  0.5f * keypoints0[i0].size;
         for(size_t i1 = 0; i1 < keypoints1.size(); i1++)
         {
-            if(nearestPointIndex >= 0 && usedMask[i1])
-                continue;
 
             float r1 = 0.5f * keypoints1[i1].size;
             float intersectRatio = calcIntersectRatio(points0t.at<Point2f>(i0), r0,
@@ -47,8 +44,6 @@ void matchKeyPoints(const vector<KeyPoint>& keypoints0, const Mat& H,
         }
 
         matches.push_back(DMatch(i0, nearestPointIndex, maxIntersectRatio));
-        if(nearestPointIndex >= 0)
-            usedMask[nearestPointIndex] = 1;
     }
 }
 

modules/features2d/test/test_invariance_utils.hpp

@@ -75,8 +75,8 @@ void scaleKeyPoints(const vector<KeyPoint>& src, vector<KeyPoint>& dst, float sc
     dst.resize(src.size());
     for (size_t i = 0; i < src.size(); i++) {
         dst[i] = src[i];
-        dst[i].pt.x *= scale;
-        dst[i].pt.y *= scale;
+        dst[i].pt.x = dst[i].pt.x * scale + (scale - 1.0f) / 2.0f;
+        dst[i].pt.y = dst[i].pt.y * scale + (scale - 1.0f) / 2.0f;
         dst[i].size *= scale;
     }
 }