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This is a short run through of how to get an HDR look from a single exposure. The tab previews are enabled by the small button next to the pipe size on the lower left. Of course, the quality you get from such a workflow cannot compete with a real HDR made of several exposures, but there may be situations where you just have forgotten your tripod or where moving parts don't allow a tripod. This stresses the image data quite a bit, so if you have a noisy camera you may get into troubles earlier.
This is more or less where the magic happens. Dynamic range compression (also tone mapping, Fattal et al.) gets the values in a useable range and increases local contrast. A little texture increase in the warm tones and halo based local contrast with a larger radius to prevent small scale halos while increasing contrast further.
The contrast filters above work only on the L* channel so the saturation is untouched and this results in weak colors. Therefore all colors get more saturated now. The green tones get more saturation to get a color contrast to the red sky. A little vignette for more drama.