Banding or moire in HDR backdrop?

[tennet]

I use Keyshot 6 Pro and I often experience moire or banding problems when rendering a visible backdrop (created in the HDR Editor). I render to 32-bit PSD and the moire don't go away when converting to 8-bit in Photoshop.. this feels wrong, since 32-bit should handle banding the best way possible. When rendering in Cinema 4D or Vray I always get very smooth results. Now I need to add lots of postwork to clean up my backdrops.

Any ideas what could be wrong? Any settings that I should change/adjust/tweak?

[tennet]

No one else experiencing this problem? I have a black HDR backdrop with a soft circular Pin Light to create the glow in the middle. It looks like the rendered gradient has "bands" from blue-grey (correct color in the center), to purple, to green and blue. Then this banding repeats itself to the very corners.

To get rid of it I need to render a separate backdrop (no floor), blur it heavy in 16-bit mode (in Photoshop) and then add some noise to it. Any ideas if there are any settings in Keyshot 6 Pro that could cause this banding? 32-bit renders shouldn't show any banding after converted to 16- or 8-bit.

[Søren]

Can you provide the scene and the environment (hdz-file) you created and possibly a 32-bit PSD/TIF or 16-bit EXR rendered image demonstrating the effect?

Do you see the same banding in the realtime view if you create the HDRI in the editor, generate the full resolution (but not saving!)?

(I have a clue to what it may be, but I need to check it first)
/Søren