I am using arcpy.DefineOverviews_management() to define Mosaic Dataset Overviews, passing the parameters resampling_method='NEAREST' and compression_method='LZW', but these settings DO NOT take effect. When I later build the Overviews and open an image file in an image viewer, I find out that it has been generated with JPEG compression!
When I use the corresponding GP-Tool "Define Overviews" in the UI with the exact same parameters/settings, then my Overviews are generated with compression LZW as I wanted.
For the life of me, I cannot find out why this doesn't work when scripted...?
When I output GP-Messages from the script with arcpy.GetMessages() it even confirms that NEAREST and LZW have been passed as parameters.
Thanks for any help!