Cannot create index on view with User Defined Function in SQL Server

According to this page:

Any functions referenced in an indexed view must be deterministic; deterministic functions return the same value each time they’re invoked with the same arguments.

GetCurrentImage is not deterministic with respect to its parameters - it uses a select, which means the results may change as the data changes - so any view using it cannot be indexed.

There's a recent documentation: https://docs.microsoft.com/en-us/sql/relational-databases/views/create-indexed-views?view=sql-server-2016

Under Additional Requirements it says: The data access property of a user-defined function must be NO SQL, and external access property must be NO.

You can check you UDF with the following statement

    SELECT ObjectPropertyEx(Object_Id('dbo.GetCurrentImage'), N'IsDeterministic') AS deterministic, 
        ObjectPropertyEx(Object_Id('dbo.GetCurrentImage'), N'IsPrecise') AS precise, 
        ObjectPropertyEx(Object_Id('dbo.GetCurrentImage'), N'IsSystemVerified') AS verified, 
        ObjectPropertyEx(Object_Id('dbo.GetCurrentImage'), N'UserDataAccess') AS UserDataAccess,
        ObjectPropertyEx(Object_Id('dbo.GetCurrentImage'), N'SystemDataAccess') AS SystemDataAccess;

The first three should give 1, the last two must be 0 for a function to be used in an indexed view.