fixed #1824

modules/features2d/src/descriptors.cpp

@@ -232,9 +232,9 @@ void OpponentColorDescriptorExtractor::computeImpl( const Mat& bgrImage, vector<
            cp[1] < channelKeypoints[1].size() &&
            cp[2] < channelKeypoints[2].size() )
     {
-        const int maxInitIdx = std::max( channelKeypoints[0][idxs[0][cp[0]]].class_id,
-                                         std::max( channelKeypoints[1][idxs[1][cp[1]]].class_id,
-                                                   channelKeypoints[2][idxs[2][cp[2]]].class_id ) );
+        const int maxInitIdx = std::max( 0, std::max( channelKeypoints[0][idxs[0][cp[0]]].class_id,
+                                                      std::max( channelKeypoints[1][idxs[1][cp[1]]].class_id,
+                                                                channelKeypoints[2][idxs[2][cp[2]]].class_id ) ) );
 
         while( channelKeypoints[0][idxs[0][cp[0]]].class_id < maxInitIdx && cp[0] < channelKeypoints[0].size() ) { cp[0]++; }
         while( channelKeypoints[1][idxs[1][cp[1]]].class_id < maxInitIdx && cp[1] < channelKeypoints[1].size() ) { cp[1]++; }

modules/features2d/test/test_features2d.cpp

@@ -1059,13 +1059,6 @@ TEST( Features2d_DescriptorExtractor_BRIEF, regression )
     test.safe_run();
 }
 
-/*TEST( Features2d_DescriptorExtractor_OpponentSIFT, regression )
-{
-    CV_DescriptorExtractorTest<L2<float> > test( "descriptor-opponent-sift", 0.18f,
-                                                 DescriptorExtractor::create("OpponentSIFT"), 8.06652f  );
-    test.safe_run();
-}*/
-
 #if CV_SSE2
 TEST( Features2d_DescriptorExtractor_Calonder_uchar, regression )
 {