The corresponding part in IrfanView FAQ is incorrect in most parts under Windows 11 (maybe it works under Windows 10). The HEVC Video Extensions (1st point) and HEIC Codec (2nd point) are blocked by either Microsoft Store app or Windows itself to protect PC. The HEIF Image Extensions (1st point again) are already installed under Windows 11, but having it doesn’t allow IrfanView to open HEIC files.
The only solution that actually worked is CopyTrans HEIC Codec (3rd point). After Installing it in Windows 11 the .heic files system association is reset. You have to select again that you want IrfanView to open this type of files. After doing this — bang! — you can finally browse HEIC files in IrfanView.Read More “How to load HEIC files in IrfanView under Windows 11?”