Slashdot Mirror
Wavy Lenses Extend Depth of Field in Digital Imaging
genegeek writes "On Feb 25 CDM Optics was awarded a patent for a new digital imaging system utilizing "Wavefront Coding" that produces images with 10-fold the depth of field of conventional lenses. The image itself is blurred until processed. Image examples are here."
Yes. Even with the new lenses, they didn't see the Slashdot Effect coming. :)
Ah yes, I know this system well. I did my master's research in extended depth-of-field optics and came across this research which pretty much blew away what I was working on.
Here's a bit of background: in photography or laser scanning (point-by-point photography, basically), you always have a trade-off between depth-of-field and aperture size (as any photographer knows). Bigger aperture means shallow depth-of-field. However, a smaller aperture means lots of wasted light (imagine closing the aperture in your camera), and this means longer exposure times, and more importantly more NOISE in your images. This is true for digital, film, or photodetector.
So the "holy grail" is to keep the aperture open but still have high depth-of-field. This system depends on changing the phase of the light, instead of the amplitude (which is what you do when you stop down a lens to a smaller aperture). That way, no light energy is blocked and wasted.
Since the phase is changed, the resulting image on the CCD or film is fuzzy and has to be "decoded". You can think of it as "encoding" the wavefront in a special way that preserves the depth of field, capturing the image, and then "decoding" it into a sharp picture. It is really amazing. I hope it shows up in consumer cameras someday, it could completely change consumer photography since most "snapshot photographers" don't care about depth of field or all that stuff. It will also be great for medical and industrial imaging.
My system was sort of a hybrid between shading the aperture (instead of a sudden stopping of light, it gradually goes to black at the edge) and phase changes. Lots of people have been working on this problem over the years, but these guys really stripped the problem down to the essence and came up with a highly optimized solution.
Yeah, and you don't have to buy film for a digital camera.
... uhh ... what? A lot of professionals and artists have begun switching to digital. There's nothing about digital that makes it any less artistic. In fact, if nothing else, it gives the artist more freedom, in that they can more easily review their work, and learn from their mistakes. The turnaround time is far shorter (ie. instantaneous), and that means that they can take more shots, and more quickly tell if they're getting the effect they desire.
Don't think this is a big deal? I'm into amateur photography, and I have a camera that I only bought 9 months ago that I've taken 1500 shots with. Have I kept them all? No. Have I printed them all? No.
And that's the point, for me. I paid $1k for a camera, and now I can take as many pictures as I'd like, without having to pay for it every damn time. The pictures that I do want printed, I can get done for very reasonable prices at places like Shutterfly. And the ones that turn out bad, or I just don't feel like printing, cost me exactly $0.
Do some math. How much would I have spent on film and processing for a traditional 35mm camera in the last 9 months, had I gone that route instead of the digital? By my reckoning, it'd be at least $500, if not more, depending on the quality of the film I purchased. Within another year or so, the camera will have paid for itself, if only in reduced cost per image.
And as for artistic purposes
-[Blaine]- "'Oh dear,' says God, 'I hadn't thought of that,' and promptly vanishes in a puff of logic."
There are at least two experienced photographers (Rob Galbraith and Michael Reichmann) who feel that the 11-megapixel Canon EOS-1Ds delivers images with detail exceeding that of 35mm and approaching (in some cases besting) medium format film. They've published some very interesting comparisons:
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http://www.robgalbraith.com/bins/content_page.a
http://www.luminous-landscape.com/reviews/camer
This may just change someone's opinon on how digital compares to film. I know it made me rethink the "conventional wisdom" that many more pixels are needed to reproduce film detail.
Cheers,
Jeremy