One of the marvelous things about a digital camera is how easy it is to fix problems in the darkroom! (Inside your computer.) As an example, I took the three pictures below at three different shutter speeds: 1/350th, 1/250th, and 1/125th of a second, ASA 100. (Maybe not the best choice for the Moon.) The first one was indistinguishable from random noise, the second was at least apparently the Moon, and third was a faint image. But once I had the chance to fiddle with them in HP Photosmart Premiere, they all came out roughly equivalent.
Click to enlarge
Click to enlarge
Click to enlarge
The data was already there--the levels were way too low on the first two pictures. Now, these aren't great pictures. When I worked at Jet Propulsion Labs, I worked on the boring part of the telemetry processing systems--not the sexy part, the pictures. One of my friends worked on the Viking image processing software--and he showed me a raw image as it arrived from the Viking Orbiter--and after post-processing. And yes, it was even more dramatic of a change than I experienced cleaning up these images.
I've written image processing software for amusement, back at the beginning of time. What you are doing is conceptually taking a collection of numbers that correspond to different brightness levels. If 0 is black, and 65535 is white, then taking the very first image, you find that effectively everything is a number between 0 and about 300; raising the image brightness involves rescaling 0 to 300 to be 0 to 65535. Obviously, the results won't be quite as precise and detailed as if you had a picture that all the values from 0 to 65535 in it. But it is astonishing how well you can fix an apparently "spoiled" picture this way!
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