這是由史丹福大學電腦科學博士Ren Ng所創辦的Lytro公司宣告，將在2011年底前針對消費市場推出採用「光場技術」的相機。它是一種可以讓使用者「先拍照，後對焦」（Shoot now, focus later）的照相技術。
所謂「光場相機」(Light Field Camera)就是能夠完整記錄透過鏡頭之大部份光的資訊如光的強度、光的軌跡、光的方向、…等，這是一般傳統相機所無法做到，或是做得不夠完整。這樣的「光場相機」，拍照時不必對焦，只要將場景拍攝下來即可，事後再以特殊的軟體處理過，即可以根據自己的喜好來定焦。有關「光場相機」所拍攝的相片，請參考http://www.lytro.com/picture_gallery，在該網頁的相片上，您可以滑鼠左鍵在任何位置點選來定焦，看看效果如何？
一般傳統相機因為只有一個鏡頭，所以我們只能有一個對焦點；如果我們希望有多個對焦點，則相對地就必須要有多個鏡頭。如果這種鏡頭可以多到與相片中的像素一樣多時，則我們就可以在該相片的任何位置來定焦了！因此，Lytro公司的「光場相機」基本構成原理(如下圖)，就是在一般相機的鏡頭(Main Lens)與影像感應器(Photosensor)中間插入一個「微型鏡頭陣列」(Microlens Array)，它是一片由排列整齊的微型鏡頭所組成的，而且每一個微型鏡頭對應一個像素。透過相機鏡頭的折射，可以將景物的影像聚集到「微型鏡頭陣列」，其上的微型鏡頭會將此聚集的影像拆散，並投射到影像感應器。
下圖是在不同的光圈下，透過「微型鏡頭陣列」(Microlens Array)影像感應器所記錄到的光場資訊。
這種「光場相機」最大的用途是，它可以讓使用者拍照時，不必擔心對焦問題，只要專心攝影構圖即可。另外，因為它可以讓我們事後再來設定焦點(零視差位置)，同時它有記錄像素之「光強度」與「光方向」的資訊，所以可以直接將它所拍攝的相片透過特殊的軟體演算(Light Field Image Based Rendering)處理成「深度圖」(Depth Map)，更進一步處理成「多視角3D影像」。
其實「光場相機」的理論在19世紀，當人類開始研發照相術時，就已經有被提出來參考，只是因為當時需要複雜的數學演算與無法即時透過顯影技術來呈現，所以最後只有單一鏡頭的照相機被商品化。如今，電腦運算與顯示技術日益精進，「光場相機」才又再度重見天日受到注意。Adobe公司也曾在2008年發表其「光場相機」(詳細請參考http://www.notcot.com/archives/2008/02/adobe-lightfiel.php)。
目前尚無有關Lytro公司的「光場相機」更詳細的資訊，不過我猜測其最初上市的產品，解析度應該不會太高，這是受限於微型鏡頭的製造技術，不過最終還是會達到最符合消費市場需求的成熟產品，我們拭目以待吧！
-JG (www.i-art3d.com)
Lytro light field camera refocuses the future of photography
消息來源：http://www.geek.com/articles/gadgets/lytro-light-field-camera-refocuses-the-future-of-photography-20110622/
日 期：2011/06/22
作 者：Jennifer Bergen
The world of photography is changing thanks to a new kind of camera introduced today by start-up company Lytro. The “light field” camera allows digital photographers to refocus a photo after it has been shot, essentially allowing you to focus on parts of the photo that would normally be blurry.
When the user views a photo captured with a light-field sensor, they can click on different areas to change the point of focus. This causes some parts to blur and otherparts to become clear. Lytro’s founder and chief executive, Ran Ng, said in a blog post that the mission is to “change photography forever, making conventional cameras a thing of the past.”
Lytro’s light field camera was developed by Ng, who started the project for his dissertation eight years ago. He submitted his dissertation on digital light field photography in 2006 to Stanford’s Department of Computer Science and has been working since then to bring the technology to the market. He now has 44 employees at his MountainView, Calif. location and has raised $50 million in three rounds.
You can see how the photos work yourself at Lytro’s “Living Pictures” gallery, but how is a camera able to capture these kinds of “living photos?” The light field is a core concept in imaging science and completely determines how a scene will appear. The light field sensor gives us a way to record the light fields, since the directional information of the rays of light are all lost when using normal camera sensors. Traditional camera sensors take in all the light rays and then record them as a single amount of light, losing all of the directional light rays captured with a light field sensor.
However, a light field camera captures all the light rays in a scene — the color, intensity, and direction of individual light rays — which is something conventional cameras can’t do. The lens and image sensor doesn’t have to focus on a specific subject and instead just collects the light information from the camera’s realm of view. It then processes the photo after it’s been shot and produces an interactive photo as the result. It can also also create a 3D image from a single lens.
The light field sensor uses software instead of many of the internal parts of traditional cameras. This allows the cameras to increase the speed of snapping a picture, and also allows for the potential of better photos taken in low-light.
The camera is said to debut at the end of the year, yet no specific date or price has been set.
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