The only software tha can reliably work with old .pdi files from one of the earlier versions of PowerPoint is PowerPoint itself, but the support for PDI file might have been dropped in latest versions of the presentation software. If you want to recover the .pdi files, you will most likely have to obtain the original version of PowerPoint and do the export from there. But otherwise no utility for pdi to jpeg conversion or something similar exists.
Updated: August 1, 2023