[Gimp-user] make the sky bluer (color selection and editing)

[ottenm <forums gimpusers com>]

I have a landscape photo filled with trees.  Through the trees you can see
dozens of sky and cloud spots in the background.  I'd like to select the blue
sky areas (a fairly large range of blues), and shade them all a little darker
toward one of the bluer sky colors in the image.

I'm comfortable with selection by color, and adjusting the threshold to include
more/less.  But I don't know how to select by color, but only within a certain
area of the image.  In other words, selecting by color and clicking on one of
the sky spots, is selecting dozens of non-sky spots all over the image that I
don't want to change (say, blue flowers, cars, and so on).

Once I get the right blue spots selected, I'd like to find a fluid way to
drag/explore the color changes.  I've used Color Exchange, but only to set one
color, then set the other color, then the thresholds, then hit ok to see how
that one change looks, then go back and change the settings and run again).  Is
there a way to get my blues selected, and watch them change as I drag toward the
darker shades, stopping when they seem just right?

Thank you for any help.  Apologies for the wordy descriptions.

-- 
ottenm (via www.gimpusers.com/forums)