The Trifid Nebula looks different in every wavelength

Put the visible-light photograph of the Trifid Nebula beside the infrared one
and you could be forgiven for thinking they are different objects. The dark
lanes that give the nebula its name — trifid, three-lobed — are its most
recognisable feature in visible light. In the infrared those same lanes are the
brightest things in the frame.

Neither image is a correction of the other. They are showing different physics.

Why the lanes invert

The lanes are dust. Dust does two things, and which one you see depends
entirely on the wavelength you are looking at.

In visible light it absorbs. Starlight passing through a dust lane is
scattered and absorbed, so the lane appears as a dark band against the glowing
gas behind it. You are seeing a silhouette.

In the infrared it emits. The same dust, warmed by the starlight it
absorbed, radiates that energy back out at longer wavelengths. So a detector
tuned to the infrared sees the lanes glowing rather than blocking.

This is the single most useful thing to understand about multi-wavelength
astronomy: the dark parts of the optical picture are often the interesting
parts, and they are dark precisely because something is there.

What was hiding in the lanes

The Spitzer Space Telescope's infrared view of the Trifid found things the
optical image could not show, because they were inside the dust:

• Embedded protostars — stars still forming, wrapped in the cloud that is
  feeding them. They will not be visible optically until they clear it.
• Stellar jets — narrow outflows fired from the poles of forming stars,
  which are among the clearest signs that a star is actively accreting.
• Cavities carved into the cloud, showing where the newest massive stars
  have begun pushing their surroundings away.

Where it is

The Trifid is about 5,400 light years away in Sagittarius — towards the centre
of our own galaxy, which is why that part of the sky is so crowded. It is
young: a star-forming region still actively making stars rather than a
finished cluster.

Why astronomers use false colour

The infrared panels are in false colour, and this is sometimes read as
decoration. It is not. The eye has no response at those wavelengths at all, so
there is no "true" colour to reproduce. Each infrared band is assigned a
visible colour so that several bands can be shown at once, and the colour then
carries real information — usually temperature, or the presence of a particular
molecule.

A red region in one of these images is not red. It is cool, or dusty, or both,
and the colour is how that fact is made visible.