Displacement faceting

[mitchino]

I'm rendering a rectangular tin with round corners. I have a basic mesh inside an SDS. It renders nice and smooth.

The tin has an embossed logo on it, so I applied a Corona material with displacement using a slightly blurred image as a displacement map.

Now when I render the corners of the tin have faceting. The logo looks smooth.

What can I do to fix this?

[4b4]

I think I dealt with a similar issue a few months back by upping the render geometry on the SDS. I'm not by my PC  so can't check.