I have not tried this myself, but the first thing that I would deal with is the contrast that the daylight creates. The extreme brightness of the tops of the leaves makes it look really bad if you just darken the shot.
Photoshop has a really nice feature called variations. I would use that to preview the image, and tweak the highlights down a lot. Also try giving the thing a little desaturation. At night colors don't show up as well.
Then you can play with the brightness/contrast all you want. Maybe a little blue hue while Ur at it.
I may try this out once I get home and post my results.
Vmerc
Photoshop has a really nice feature called variations. I would use that to preview the image, and tweak the highlights down a lot. Also try giving the thing a little desaturation. At night colors don't show up as well.
Then you can play with the brightness/contrast all you want. Maybe a little blue hue while Ur at it.
I may try this out once I get home and post my results.
Vmerc