Hi Jim,
The answer is no, it is not supported.
However, there is often a confusion between video and image bit depth.
With RGB, 16 bits means per color channel. So at 16 bits per channel, that’s a total of 48 bits without an alpha channel.
This is often used for High Dynamic Range images that Photoshop can process.
In Photoshop, you can change the mode to 8 bits per channel.
Vince Becquiot
Kaptis Studios
San Francisco – Bay Area