RCW79 (OBSID=1342188880), a very structured galactic star-forming region. Left: Original map showing high amplitudes of fluctuations. Right: Structure noise map of the same region. Log scaling was used in both panels. The structure noise map shows that around the bright sources, the fluctuation of the background at a distance of ~30″ is higher than in places where the background is flat. If a pixel has a high value in the structure noise map, it means that in the vicinity of that pixel, the fluctuation of the original map is high.