I have installed "CopyTrans HEIC for Windows". Preview Pane of Explorer, Windows Media Center, system picture viewer are able to display HEIC file. One oddity is that "Print" called directly from Explorer (and from DOpus) throws error window "System Windows cannot find this picture. Check localization and try again", however system picture viewer is able to print the picture.
DOpus Preview Pane and DOpus picture viewer displays error saying that "No compatible WIC decoder was found".
Directory Opus 13.10.2 (Beta) Build 9021 x64
OS 6.1 (B:7601 P:2 T:1) SP 1.0 "Service Pack 1"
If I understand the DOpus plugin (opuswic.dll) is exclusive not only to extensions, but also to vendor of particular WIC codec.
No matter what other WIC codec I have installed, Explorer, Windows Media Center, any other program supporting WIC may benefit from it, but DOpus does not (by design of the plugin).
It was written to work with the CopyTrans codec as well, and used to in the past, at least. Maybe the codec ID changed or something, so it isn't being recognised.
AFAIK the CopyTrans codec was only relevant back when there were versions of Windows which didn't have the Microsoft HEIC codec as an option. Since that's no longer the case for any version of Windows still getting security updates, I'm not aware of any reason to still use the CopyTrans codec over the Microsoft one.
Microsoft's codec is not available for given version of Windows? Using a version of Windows not supported by Microsoft, but still supported by Directory Opus? Potentially: other codec (not necessarily CopyTrans) is better than counterpart from Microsoft?