It would be easy to assume that the awesome deep space images NASA has been sharing with us for years are simply beamed down from various satellites and space craft before being revealed to the public, but the actual process of revising and colorizing is much more interesting.
Wired reports on the multi-step process; one of the more interesting steps in the process is the second one:
2// Blend the wavelengths
It may look seamless, but the portrait above is actually a composite of images taken in different wavelengths. (For instance, the infrared comes from the Spitzer Space Telescope, and the optical is from the Hubble Space Telescope.) Visualizers then blend and smooth Cass’ problem areas. For the image from Chandra, regions with fewer photons get smeared into soft dust clouds, while more photon-rich parts appear sharper.
Hit up the link below for the full rundown on the process.