filmscanners: Re: filmscanners: New auto adjust software on it's way
Preston wrote: (I remember an article in Scientific American 15 to 20 years ago about the improvement of photographic images (I think they were alluding to spy satellite images) to eliminate/reduce blur due to camera motion and lens focus (or lack thereof). That article may have been concerned with something I learned about at university - inverse fourier transforms. If you can map the aberrations in a satellite lens system while it is still on earth and make a transform from it, you can actually use an inverse transform to remove the aberrations. The result is a sharper image than the camera actually saw. I know this technology has been used with military spy satellite images, but I don't know where else it may have been used. It would be difficult to use on a commercial basis due to the need to map the aberrations of the lens system. It would be wonderful if it could be used in a scanner, because theoretically it ought to be possible to remove aliasing and lens aberrations from the scanner optics. (but I've discussed it before and I won't bore everyone with it again! :) Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
Re: filmscanners: Re: filmscanners: New auto adjust software on it's way
Rob writes: If you can map the aberrations in a satellite lens system while it is still on earth and make a transform from it, you can actually use an inverse transform to remove the aberrations. The result is a sharper image than the camera actually saw. No, it is just a _different_ image. You cannot create information that was not captured by the camera in the first place, but you can rearrange it so that it looks more useful to a human being. If you know the exact way in which light rays will be misdirected in a lens, you can redirect them through computer processing to arrive at an image that shows approximately what a perfect lens would have produced. However, if any aberrations or other defects caused a loss of information in the captured image, there is nothing you can do to restore that information. An area that is simply outside the plane of focus, for example, cannot be put into sharp focus by post processing. It would be difficult to use on a commercial basis due to the need to map the aberrations of the lens system. It would be cheaper just to design and build a better lens. The military uses this method because they are already using the best lenses that can be made, and so the only way to do better is with a technique that is even more expensive than designing good lenses. But for ordinary photographic lenses, which generally do not push the limits of what is possible, it would be cheaper to just make the lens better than to spend money on extremely costly analysis and post-processing.
Re: filmscanners: Re: filmscanners: New auto adjust software on it's way
That article may have been concerned with something I learned about at university - inverse fourier transforms. Right. It did involve fourier transforms of some sort (I used to have some idea of what that means) but applied to the image not the lens, if I am remembering right. John M.
Re: filmscanners: Re: filmscanners: New auto adjust software on it's way
There are a few software packages designed to do just this for astronomical images.. Lucy-Richardson Deconvolution, Maximum Entropy plus a couple more algorithms.. very cpu intensive (forget about using a Pentium 200). I have not been impressed by the results, too much work for an incremental improvement in image quality.. at the end I just think that its better to use a good lens, properly focused, in the first place.. it does have a place in removing environmental blurring effects. These algorithms were designed to improve the images coming from the Hubble Space Telescope, before the optics were repaired in orbit. Here is a page with before and after results: http://www.image-scientist.com/deconvolve.htm Perhaps I can see something like this added to scanning software.. but note that the algorithm has to be finely tuned to the hardware. Rob Geraghty [EMAIL PROTECTED] wrote: That article may have been concerned with something I learned about at university - inverse fourier transforms. If you can map the aberrations in a satellite lens system while it is still on earth and make a transform from it, you can actually use an inverse transform to remove the aberrations. The result is a sharper image than the camera actually saw. I know this technology has been used with military spy satellite images, but I don't know where else it may have been used. It would be difficult to use on a commercial basis due to the need to map the aberrations of the lens system. It would be wonderful if it could be used in a scanner, because theoretically it ought to be possible to remove aliasing and lens aberrations from the scanner optics. (but I've discussed it before and I won't bore everyone with it again! :) Rob Herm Astropics http://home.att.net/~hermperez
