ENH: add a method to retrieve the number of Overviews into GDALImageIO
ENH: add a method to retrieve the number of Overviews into GDALImageIO

orfeotoolbox/OTB,orfeotoolbox/OTB,orfeotoolbox/OTB,orfeotoolbox/OTB,orfeotoolbox/OTB,orfeotoolbox/OTB