ENH: manage the case where the file have already overviews

Modules/IO/IOGDAL/src/otbGDALImageIO.cxx

@@ -496,6 +496,9 @@ unsigned int GDALImageIO::GetOverviewsCount()
     return dataset->GetRasterBand(1)->GetOverviewCount();
     }
 
+  if (dataset->GetRasterBand(1)->GetOverviewCount())
+    return dataset->GetRasterBand(1)->GetOverviewCount();
+
   // default case: compute overviews until one of the dimensions is 1
   bool flagStop = false;
   unsigned int possibleOverviewCount = 0;

Modules/IO/IOGDAL/test/otbGDALOverviewsBuilder.cxx

@@ -56,9 +56,9 @@ int otbGDALOverviewsBuilder(int itkNotUsed(argc), char* argv[])
   io->SetFileName(inputFilename);
   io->CanReadFile(inputFilename);
   io->ReadImageInformation();
-  //std::cout << io->GetNumberOfOverviews() << std::endl;
+  //std::cout << io->GetOverviewsCount() << std::endl;
 
-  if (io->GetNumberOfOverviews() != static_cast<unsigned int>(nbResolution)-1 )
+  if (io->GetOverviewsCount() != static_cast<unsigned int>(nbResolution)-1 )
     return EXIT_FAILURE;
 
   return EXIT_SUCCESS;