Here's another take on blue:
I read about colour replacement using LAB space and have been wanting to try -- the above is the result.
1. I decomposed to LAB. On the B layer, I did a curve adjustment in an upside down U, like so (doing the inverse, or doing the curves on the A layer will produce different shifts):
I then recomposed which gave the basic colour replacement, giving me a blue cap.
2. On the recomposed image I did a bit of levels and curves to brighten the thing up, and especially to get some background.
3. I wanted to go with the misty ethereal look, so I did an Orton layer, using a radius of 20 for the blur, and overlay at about 70% for the blend mode.
4. I then lightened up the background a bit again, as the overlay had darkened it.
5. Finally I did noise reduction in GIMP using my new favourite plug-in, GREYCstoration. I tweaked the settings a bit, figuring that any resulting softness would just add to the effect.
EL