ENH: add otbUnaryFunctorImageFilter which is able to change the number of channel with VectorImage

Code/BasicFilters/otbUnaryFunctorImageFilter.h

+/*=========================================================================
+
+  Program:   ORFEO Toolbox
+  Language:  C++
+  Date:      $Date$
+  Version:   $Revision$
+
+
+  Copyright (c) Centre National d'Etudes Spatiales. All rights reserved.
+  See OTBCopyright.txt for details.
+
+
+     This software is distributed WITHOUT ANY WARRANTY; without even
+     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+     PURPOSE.  See the above copyright notices for more information.
+
+=========================================================================*/
+#ifndef __otbUnaryFunctorImageFilter_h
+#define __otbUnaryFunctorImageFilter_h
+
+#include "itkUnaryFunctorImageFilter.h"
+
+namespace otb
+{
+/**
+ * \class UnaryFunctorImage
+ * \brief Implements pixel-wise generic operation on one image.
+ *
+ * Add the capability to change the number of channel when operation on
+ * VectorImage compared to the itk::UnaryFunctorImageFilter
+ *
+ * The number of channel is provided by the functor: TFunction::OutputSize. If
+ * this number is lower or equal to zero, the behavior of the itk::UnaryFunctorImageFilter
+ * remains unchanged.
+ *
+ * \sa itk::UnaryFunctorImageFilter
+ */
+template <class TInputImage, class TOutputImage, class TFunction >
+class ITK_EXPORT UnaryFunctorImageFilter : public itk::UnaryFunctorImageFilter<TInputImage,TOutputImage, TFunction>
+{
+public:
+  /** Standard class typedefs. */
+  typedef UnaryFunctorImageFilter                                            Self;
+  typedef itk::UnaryFunctorImageFilter<TInputImage,TOutputImage, TFunction>  Superclass;
+  typedef itk::SmartPointer<Self>                                            Pointer;
+  typedef itk::SmartPointer<const Self>                                      ConstPointer;
+
+  /** Method for creation through the object factory. */
+  itkNewMacro(Self);
+
+  /** Run-time type information (and related methods). */
+  itkTypeMacro(UnaryFunctorImageFilter, itk::UnaryFunctorImageFilter);
+
+protected:
+  UnaryFunctorImageFilter() {};
+  virtual ~UnaryFunctorImageFilter() {};
+
+  /** UnaryFunctorImageFilter can produce an image which has a different number of bands
+   * than its input image.  As such, UnaryFunctorImageFilter
+   * needs to provide an implementation for
+   * GenerateOutputInformation() in order to inform the pipeline
+   * execution model.  The original documentation of this method is
+   * below.
+   *
+   * \sa ProcessObject::GenerateOutputInformaton()  */
+  virtual void GenerateOutputInformation()
+  {
+    Superclass::GenerateOutputInformation();
+    typename Superclass::OutputImagePointer outputPtr = this->GetOutput();
+    outputPtr->SetNumberOfComponentsPerPixel( // propagate vector length info
+        this->GetFunctor().GetOutputSize());
+  }
+
+
+private:
+  UnaryFunctorImageFilter(const Self&); //purposely not implemented
+  void operator=(const Self&); //purposely not implemented
+
+};
+
+} // end namespace otb
+
+#endif