Image files .IVU or .IVUE, and IVUC (compressed IVUE) can be opened in MAC Classic OS on PPC platforms using Tiger (10.4.11) and on any MAC OS 8-9.2.2 OS computer. The primary application for viewing an IVU file and converting it to TIF is ImageView 2.5.1 which runs in classic or OS9.2.2 and earlier. The files can be opened to create a FITS file using Live Picture 2.5 - 2.6.2 also a classic or OS9 application.
These files can be recognized by MAC OS finder and FITS file will show a small thumbnail, though IVU files just show an icon. By dragging the file in finder to the ImageView application the file will open up for viewing and converting to TIF. Live Picture 2.5 + can open a FITS or IVU file from its own "open" dialog. If you also set the deafault application for IVU files to ImageView 2.5, then any IVU can be opened driectly from Finder. FITS files can be dragged to an open LivePIcture 2.5+ application where it will search fpr the related IVU images and open the FITS file. From LP the file can be edited and built to a TIFF file of any size and resolution.
Graphic Converter (GKON) - all versions since the 1990s will recognize both FITS and IVU and will show a thumbnail of both files. GKON can be set to open IVU images in ImageView 2.5.
An old Cumulus 5.5 Classic app will catalog IVU, IVUE, IVUC, FITS, FIT2 images and will show thumbnails in the catalog, which can be opened by ImageView or LivePicture.
For more info go to my site WAESHAEL.COM for some user guides and examples. This is a non-commercial site.