I find it interesting that the idea of combining bracketed exposures to increase the recorded range of brightness has gone mainstream (known as HDR) to, the point where it is built into the camera's jpeg rendering. (Aside: now that cameras are powerful enough to do that, sensor latitude has improved so we don't need to overcome it)
But there are other ways of cobining exposures. I've heard of stacking to scan over a depth of field, with various programs available to aid in that.
What I'm interested in at the moment is improving low-light/high-ISO shots through multiple exposures.
I read the suggestion here of stacking them in Photoshop (alignment of such stacks is now built-in) and simply taking the median of each pixel. That gave useful improvement from a burst of normal exposed shots.
But it could be much fancier than just taking the median. Besides smarter combining of the above stack, another variation is to make each camera exposure much shorter than the desired exposure, and add them together afterwards. In effect, the long exposure has the sansor buckets measued at intervals rather than only once. Just adding gets me nowhere better, but that allows profiling the variance and removing noise, in principle better than just using the median.
Is there existing software for doing these things? Since the techniques have come down to us from astronomy, the dSLR astrophotography enthusiasts might have brought them to home PCs. Assuming such software is not too specific for that kind of image, is that available?
Another thing I noticed from having to align a burst of shots, even from a tripod, is that they are not perfectly in register. That can be used to advantage: in some places even the dumb median method improved antialiasing of a straight line due to the jitter. I recall (again, from this site) this being done on purpose by astrophotography where it was (confusingly to me) called dithering (it means something different in computer graphics) for a closely related improvement. With whole-pixel alignment the simple stacking can he hurt or helped in certain ways due to sub-pixel registration differences, but a smarter stacker could know about that to get even better results, to the point where it is beneficial. Are any image-stacking programs out there doing stuff like this?