I'd like to use a mediawiki to manage a collection of scanned images in TIFF format. It would be most helpful if thumbnails would be created as they are for other image file formats. ImageMagick handles tiff files just fine but mediawiki doesn't seem to. I've added .tif and .tiff to $wgFileExtensions and I can upload the files but they are not getting thumbnails. Is there anything special I need to do to get thumbnails from tiff images?