Can Advanced Tiff Editor open .heic files or is there an extension available
that I can download to do this?
HEIF/HEIC loading is supported if Windows includes drivers for it.
Generally you need to install HEVC Video Extensions from the Device Manufacturer:
https://www.microsoft.com/en-au/p/hevc-video-extensions-from-device-manufacturer/9n4wgh0z6vhq
And on older systems you may also need HEIF Image Extensions:
https://www.microsoft.com/en-au/p/heif-image-extensions/9pmmsr1cgpwg
Both are free on the Microsoft Store.
