The Null Device

Shoot first, focus later

Scientists have developed a camera that takes pictures that can be refocussed afterward, by keeping track not only of the intensity of incoming light but of its angle as well.
Now, Pat Hanrahan and his team at Stanford University have figured out how to adjust the light rays after they have reached the camera. They inserted a sheet of 90,000 lenses, each just 125 micrometres across, between the camera's main lens and the image sensor. The angle of the light rays that strike each microlens is recorded, as well as the amount of light arriving along each ray. Software can then be used to adjust these values for each microlens to reconstruct what the image would have looked like if it had been properly focused. That also means any part of the image can be refocused - not just the main subject.
The researchers' page on the "light field camera" includes papers and a gallery of refocusable images, and videos of focussing through a frozen moment. The examples look uncanny, as if splashes of water frozen in space were unbelievably intricate dioramas.

Applications of this technology include surveillance (where being able to change focus after the fact would often be useful) and motion photography; I imagine we may see this in films, music videos and ads soon enough as well.

There are 4 comments on "Shoot first, focus later":

Posted by: toby http:// Thu Nov 17 22:20:27 2005

It's hypercool, but there was something slightly wrong about the colour/sharpness of the images, which made me think that the processing changes things slightly -- that alone might make it unusable in films, where, presumably, you're not going to shoot the entire thing with that camera.

But as soon as it can be adapted to moving images, it'll be the new matrix effect, you can be sure.

Posted by: acb Fri Nov 18 09:34:15 2005

Then again, perhaps it's nothing that judicious colour-grading wouldn't fix.

Posted by: toby http:// Sat Nov 19 13:30:44 2005

Looking at the paper, you also need a ridiculously high resolution CCD to get an average resolution focusable image, so that probably makes it impractical for movie use.

Posted by: acb Sat Nov 19 20:58:59 2005

At least until they improve CCD manufacturing technologies to the point when they can churn them out at reasonable prices.

Given how display manufacturing techniques have been advancing (remember how, a few years ago, LCDs cost a fortune because only a tiny proportion of displays manufactured were usable?), I imagine that similar advances in CCD manufacturing should not be ruled out.