ENH: add information about overviews into the JPEG2000ImageIO

Code/IO/otbJPEG2000ImageIO.cxx

@@ -853,7 +853,6 @@ bool JPEG2000ImageIO::GetResolutionInfo(std::vector<unsigned int>& res, std::vec
   return true;
 }
 
-/** Get all resolution in jpeg2000 file */
 bool JPEG2000ImageIO::GetAvailableResolutions(std::vector<unsigned int>& res)
 {
   res = this->m_InternalReaders[0]->GetAvailableResolutions();
@@ -864,6 +863,18 @@ bool JPEG2000ImageIO::GetAvailableResolutions(std::vector<unsigned int>& res)
   return true;
 }
 
+unsigned int JPEG2000ImageIO::GetNumberOfOverviews()
+{
+  std::vector<unsigned int> tempResList = this->m_InternalReaders[0]->GetAvailableResolutions();
+
+  if (tempResList.empty())
+    {
+    itkExceptionMacro(<< "Available resolutions in JPEG2000 is empty");
+    }
+
+  return tempResList.size() - 1;
+}
+
 
 // Read image
 void JPEG2000ImageIO::Read(void* buffer)

Code/IO/otbJPEG2000ImageIO.h

@@ -70,9 +70,15 @@ public:
   /** Get Info about all resolution in jpeg2000 file */
   bool GetResolutionInfo(std::vector<unsigned int>& res, std::vector<std::string>& desc);
 
-  /** Get all resolutions in jpeg2000 file */
+  /** Get all resolution in jpeg2000 file from res = 0 which is the full resolution
+   *   to nbReslution-1 which is most degraded*/
   bool GetAvailableResolutions(std::vector<unsigned int>& res);
 
+  /** Get number of available overviews in the jpeg2000 file
+   *  ( if return = 0 => no overviews available because only one resolution
+   *  is encoded in the file) */
+  unsigned int GetNumberOfOverviews();
+
   /** Reads the data from disk into the memory buffer provided. */
   virtual void Read(void* buffer);
 
@@ -136,6 +142,9 @@ private:
   /** Resolution factor*/
   unsigned int m_ResolutionFactor;
 
+  /** */
+  unsigned int m_NumberOfOverviews;
+
   /** Size of the cache used to reduce number of decoding operations*/
   unsigned int m_CacheSizeInByte;