ENH: nbcomp is automatically set to image numberOfComponents if excedd JIRA OTB#296.

Applications/FeatureExtraction/otbDimensionalityReduction.cxx

@@ -180,6 +180,21 @@ private:
 
   void DoUpdateParameters()
   {
+		if (HasValue("in"))
+		{
+			FloatVectorImageType::Pointer inImage = this->GetParameterImage<FloatVectorImageType> ("in");
+			inImage->UpdateOutputInformation();
+
+			// Update the values of the channels to be selected
+			unsigned int	nbComponents = inImage->GetNumberOfComponentsPerPixel();
+			unsigned int nbComp = static_cast<unsigned int> (GetParameterInt("nbcomp"));
+			if (nbComp > nbComponents)
+			{
+				SetParameterInt("nbcomp", nbComponents);
+				otbAppLogINFO( << "number of selected components can't exceed image dimension : "<<nbComponents );
+			}
+
+		}
   }
 
   void DoExecute()