All the existing (Interop) C# libraries I've found wrap a 32 bit version of libwebp.dll
As a result, I (correctly) get an ImageFormatException when I try to use the wrapper from a 64 bit program... Unfortunately, I can't find a 64 bit version of libwebp.dll or a suitable wrapper...
Ideally, I'd like to see a managed code implementation. Does anyone know of such a thing?