correct NCC metric

Author: Cristy

magick/compare.c

@@ -2241,7 +2241,7 @@ MagickExport Image *SimilarityMetricImage(Image *image,const Image *reconstruct,
     similarity_info.x,similarity_info.y,exception);
   progress=0;
   similarity_view=AcquireVirtualCacheView(similarity_image,exception);
-#if defined(MAGICKCORE_OPENMP_SUPPORT)
+#if defined(MMAGICKCORE_OPENMP_SUPPORT)
   #pragma omp parallel for schedule(static) shared(status,similarity_info) \
     magick_number_threads(image,reconstruct,similarity_image->rows << 2,1)
 #endif    
@@ -2355,10 +2355,20 @@ MagickExport Image *SimilarityMetricImage(Image *image,const Image *reconstruct,
       }
   }
   similarity_view=DestroyCacheView(similarity_view);
+  switch (metric)
+  {       
+    case NormalizedCrossCorrelationErrorMetric:
+    { 
+      similarity_info.similarity=1.0-similarity_info.similarity;
+      break;
+    }   
+    default:
+      break;
+  }   
+  if (status == MagickFalse)
+    similarity_image=DestroyImage(similarity_image);
   *similarity_metric=similarity_info.similarity;
   offset->x=similarity_info.x;
   offset->y=similarity_info.y;
-  if (status == MagickFalse)
-    similarity_image=DestroyImage(similarity_image);
   return(similarity_image);
 }