Index: src/cv/cvsurf.cpp
===================================================================
--- src/cv/cvsurf.cpp	(version 3030)
+++ src/cv/cvsurf.cpp	(working copy)
@@ -724,6 +724,13 @@
 	}
 
     N = keypoints->total;
+
+	if ( N == 0 ) 
+	{
+		// no key points found; nothing to do 
+		return;
+	}
+
     if( _descriptors )
     {
         descriptors = cvCreateSeq( 0, sizeof(CvSeq),
@@ -844,6 +851,13 @@
     MemStorage storage(cvCreateMemStorage(0));
     Seq<CvSURFPoint> kp;
     cvExtractSURF(&_img, pmask, &kp.seq, 0, storage, *(const CvSURFParams*)this, 0);
+
+	if ( kp.empty() ) 
+	{
+		// no key points
+		return; 
+	}
+
     Seq<CvSURFPoint>::iterator it = kp.begin();
     size_t i, n = kp.size();
     keypoints.resize(n);
@@ -880,6 +894,13 @@
     
     cvExtractSURF(&_img, pmask, &kp.seq, &d, storage,
         *(const CvSURFParams*)this, useProvidedKeypoints);
+
+	if ( kp.empty() ) 
+	{
+		// no key points
+		return; 
+	}
+
     if( !useProvidedKeypoints )
     {
         Seq<CvSURFPoint>::iterator it = kp.begin();