Perhaps the Digimarc filter only operates on 8-bit RGB photos (which JPGs would be) and the image you’re trying it on is something else. You can use Image / Mode to convert. If you’re working with a photo from a camera raw format, then your Workflow options in ACR may be set for 16-bits. It is probably good that you use 16-bits out of ACR into PS but you will have to convert to 8-bits sometimes.
I don't know if I entered my remarks correctly so I am doing it again.
You are correct. When I switched the photoshop file from 16 bits to 8 bits Digimarc was available. I entered the copyright year and then switched back to a 16 bit photoshop file. I saved the file as a JPG and the Digimarc info stayed with the new JPG file. However what I would like to know am I limiting my options by converting to an eight bit file and then back to a 16 bit file after entering the digimarc info?
As I wrote in my last reply, Thanks for the quick response.
When you convert from 16-bits to 8-bits you lose the finer gradations in color and brightness. 16-bits has 65536 levels of red, green, and blue. 8-bits only has 255 levels of red, green and blue.
You may not be able to see the difference if you do the conversion from 16-bits to 8=bits as the last step of your adjustment process, just before you save your JPG, but if you are doing more adjustments to do in Photoshop after ACR, then you may see banding in a smooth sky gradient, or color posterization (banding that jumps from one color to another) if colors or brightness are adjusted significantly.
If the only thing you’re doing in Photoshop is adding Digimarc and saving as JPG then there isn’t any problem and no need to even convert back to 16-bits before saving as JPG because JPG needs 8-bits before you can save to it.