Lytro: Why u can decide what’s in focus AFTER taking the shot

by Sebastian WöberJune 23^rd, 2011

So there’s this new kind of camera technology that lets you focus your image after you have taken it. Right now it is only a stills camera, but it doesn’t take much observation of how things go to figure out that we’ll see this technology implemented in future video cameras, possibly video dslrs ;) sooner or later.

The news about this camera is spreading fast but few seem to understand how it actually works. I read the description on the Lytro site and it seems to me they wanted to make it sound really sophisticated, complicated and futuristic, but in reality it’s fairly simple. Let me tell you right away that it doesn’t take successive shots real quick. If you look at the interactive image on the left that’s what could come to your mind, but that’s very wrong. The Lytro Camera will truly give you any focus field you desire. Read on to understand how it works.

Alright, so first of all it’s important to understand that most of the magic is taking place on the sensor itself. A conventional image sensor’s receptors can only understand which light rays it is hit by. The new image sensor of the Lytro camera, which has an array of micro lenses in front of it also understands the angle of these light rays thus unlocking the information that is needed to reproduce any focus field you like. The Lytro guys call this technology “Digital Light Field Photography”.

From the Lytro page:

By substituting powerful software for many of the internal parts of regular cameras, light field processing introduces new capabilities that were never before possible. Sophisticated algorithms use the full light field to unleash new ways to make and view pictures.

Yeah, sounds nice but I don’t understand a word. So here’s the translation:
The software interprets the angles of the light rays to make selective focusing in post possible.

Why does this work? Because when you shift focus what happens in the lens is that the light rays’ directions are changed thus changing the points they hit on the sensor. When you change a light rays direction you also change it’s angle. This way the sensor (+software) understands where exactly each light ray is coming from and can reproduce a blur free image or any focus field you like.

This way you can correct bad focus in post, you can repair a wrongly set focus and you can generate a high depth of field.

The first digital photo camera with this technology is set to be released this year.

If you’re really into that read the dissertation by Lytro CEO Ren Ng.

more “living pictures” on the Lytro site

via nytimes.com