BUG: Skip single pixel textures

fixes #68

Author: maekclena

include/itkCoocurrenceTextureFeaturesImageFilter.hxx

@@ -228,9 +228,14 @@ CoocurrenceTextureFeaturesImageFilter<TInputImage, TOutputImage, TMaskImage>
           ++hist[currentInNeighborhoodPixelIntensity][pixelIntensity];
           }
         }
-      // Compute the run length features
-      this->ComputeFeatures( hist, totalNumberOfFreq, outputPixel);
-      outputIt.Set(outputPixel);
+
+      // No coocurrences means we are computing the texture of a single pixel, which is undefined
+      if ( totalNumberOfFreq != 0 )
+      {
+        // Compute the run length features
+        this->ComputeFeatures( hist, totalNumberOfFreq, outputPixel);
+        outputIt.Set(outputPixel);
+      }
 
       ++inputNIt;
       ++outputIt;