On 11/1/2011 4:47 PM, Darren Addy wrote:
What follows is a post about Lytro technology from another list I
subscribe to... (informative, so thought I would share).
- - -
It's a cool idea. It does trade off
pixels of the sensor against the ability to focus at any distance in a
single image. Here's a link to a very well-written article (by the CEO of
Lytro) with some very good images which help to clarify how it works.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.163.488&rep=rep1&type=pdf
or
http://www.graphics.stanford.edu/papers/lfcamera/lfcamera-150dpi.pdf
One could probably condense the article into a couple paragraphs, but it
would be rather unintelligible, I fear. Basically you start with a huge
number of pixels on the sensor -- 16 Mpx in the paper -- and group them
into many tiny fields each behind its own microlens. The paper has 292×292
such tiny fields each containing somewhat over 100 pixels. That basically
lets you figure out where every ray which strikes the main lens comes from
(see the article). You can post-process any single image to form a
perfectly focused image of any plane in the field, from very close out to
infinity -- but you only get a perfectly focused image of 80,000 pixels.
That's not terrible -- it corresponds to about a quarter-VGA (QVGA) image.
Depends on what your needs are. If you shoot very dynamic scenes with a lot
of depth of field in the scene, it can be a godsend, because you can later
decide which plane to focus on. In fact, with only slightly sophisticated
image processing you can make everything come out in focus.
So what you're saying is that with a lot of processing power you can
achieve a depth of focus and resolution easily approachable by a P&S
camera with 1/2.5 1 mp sensor at less than 10% of the resolution.
- - -
My comment: the relatively low number of pixels (or conversely, the
HIGH number of megapixel sensor you need to get a decent number of
finished image pixels) probably makes this a technology that will need
a lot more time before it is really practical for imaging larger
prints.
Darren Addy
Kearney, Nebraska
--
Don't lose heart! They might want to cut it out, and they'll want to avoid a
lengthily search.
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