If you have no detail in the shadows and no detail in the highlights, then clearly downsampling will not create detail where non previously existed
Removing the lens cap may help.
I asked the following question. Can we expect a higher DR and S/N than the D3 produces, when D3X files are downsized to 12mp?
All right, you did not claim it but asked.
The issue is, tha the dynamic range in photographic sense is not the same as in engineering sense. It involves not only the lack of noise but the presence of details as well; otherwise the dynamic range could be increased by replacing all lower pixel values with a very low constant.
Of course, the level of exectable details is different between the D3 and the D3X due to the different resolution. Thus it is possible to increase the DR while descreasing the resolution (this is, what Emil encodes with "lower spatial frequency"). The problem is, that one could gain the impression in these threads that the image could be "enhanced" by downsizing, and that is the nonsense. The result will always
be worse than the original.
by virtue of the lower noise resulting from the downsampling, one could also expect a correspondingly greater DR in relation to the D3 image, but not of course in relation to the original D3X image
Anyone buying a 24 Mpix camera for twice the price of a 12 Mpix camera with the intention of changing that back into another 12 Mpix camera is not fit for photography. This issue does not deserve any discussion.