BW processing

VA3_0239, originally uploaded by gugs.

I tried a strange processing on this one, playing with the different color channels, to get more details in the sky, but resulting in a strange "negative" effect in some places. I like the result, but this is of course a matter of taste. This shot has been taken in the center of Brussels, with a Nikkor 24-70 2.8 lens on a Nikon D3 camera, for what it's worth.
Any comments or suggestions welcome.