I'm incorrect. Apologies.
Although I had downloaded Damien's new version of inpaintn, I had earlier used the older version (that I had neglected to delete), in a folder that put it ahead of the new version.
The call to test4DCTNANDIDCTN can be eliminated because the functions dctn and idctn are now included in the inpaintn.m file.
Otherwise, works well. Results in my application compare reasonably with John D'Errico's inpaint_nans3, and is faster.