I used Pixinsight's background smoothing function to reduce noise
in dimmer portions of the image. Stretching the image to bring out
faint detail also generated a mottled noisy background.
Pixinsight addressed this problem with some success.
Compare this image to the "before" version
at http://www.pbase.com/steelnavy/image/82295240

Located in the constellation of Cygnus, the Veil Nebula Complex
of which Pickering's Triangle is the central portion,
floats approximately 1,400 light years from our home planet;
the remains of a supernova event that took place in pre-history,
between 5,000 and 10,000 years ago. It's estimated that the light
from this explosion was visible in the night sky for several months
and easily cast shadows on the ground for over a week after it
initially detonated.

I imaged this portion of the Veil Nebula in Cygnus using a 4.5nm
HA filter. 195 minutes total in 15 minute sub exposures.
Applied digital development in Maxim, then levels and curves
in Photoshop. Best FWHM readings at start of session were 1.9
Occasional thin scattered clouds wandered by, otherwise clear.
CCD temp -17C. Image was dark subtracted but no flats used.