Thomas Steffen wrote:
The other issue was that convert would not recognise ghostscript. I read that @PSdelegate@ in delegates.xml relies on registry keys, and indeed replacing it with gswin32c.exe solved the issue. This was necessary to get previews working for eps files.
The build-in ImageMagick does not rely on registry keys but uses the environment variables set by LyXLauncher (see the source for details) to get the location of the Ghostscript directories. Note that not only @PSdelegate@ is relevant but also the font directory etc.