Build 329 brightness glitch

AutoCAD 2013.

When running a test rendering at 1500x1000 pixels in Walkabout, the exterior, sunlit, single-channel rendering looks great with the following settings:

Brightness: 0.0

Burn: 0.0

Saturation: 0.0

Indirect: OFF

Ambient: Medium (1.00)

When I change ONLY the resolution to 10,800x7200 for the final rendering in Walkabout, the image is almost completely washed out, even after several passes. The Brightness slider needs to be set to -.50 to get the image back to a close match with the original.

Going back to the lower resolution requires setting the Brightness back to 0.0.

Odd...

-Bill