6 15-second exposures of the same scene were digitally combined to increase brightness, reduce contrast, and reduce grain. The standing waves visible in the center of this image are not very evident to the unaided eye, because of turbulence; the peaks and troughs of the waves change markedly in location and height from one second to the next.

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10478 AutoLLN +79 SubFilt 80+81 SubFilt 82+83 1136x852 IvQ90
sharpen, stretch histogram