Gary I--
I just got Affinity Photo (Windows) after using PhotoPlus for a couple of years. About a third of my photos are saved as .spp files, which aren't accessible in Affinity Photo. I stumbled upon this solution: open the .spp file in Photo Plus (if you have it), then Export as a .jpg (or other common) file. Can be saved in the same folder if you want (as it has a different file name extension it will not over-write the old file). I'm reluctant to delete the old .spp version yet. The new .jpg file seems to take up less storage space than the .spp which makes me wonder if there's a significant difference.
