Thursday, May 29, 2014

Lightfield Photography Part 2 (Lytro Illum)

Lytro Illum addio alle foto sfocate
Lytro Illum  (Photo credit: KoFahu meets the Mitropa)
I talked a lot in the previous part of this article about how light field photography works and why it's useful. In this part I'm going to focus primarily on the enhancements to the Illum which is the recently announced second generations Lytro camera. I'm going to focus mostly on why the enhancements in the Illum are potentially useful even for serious photographers.

As I opined before, too much emphasis is put on the Lytro's ability to refocus. The fact of the matter is that this ability to refocus comes at a cost. I've often referred to the first generation Lytro as a great proof of concept and it was; but it wasn't without some fairly significant faults. Those faults caused a fair amount of consternation in some circles and are likely causing Lytro some headwinds right now. If you read any of the comment sections associated with articles written about the Illum you'll know what I'm talking about.

In my opinion Lytro made a mistake in their marketing of the first generation camera. That mistake was in focusing too much on the megapixels captured while avoiding at all costs any mention of the resolution of exported 2D images. On the one hand this was understandable. 1.1 megapixels stopped being an impressive resolution a decade or more ago. The limited resolution was also at odds with their desire to present the Lytro camera as a premium product at a premium price. In addition it was generally difficult to get a good quality picture even at the 1.1 megapixel export resolution. Pictures were often soft and colors were subdued and muted in my experience. It was rare that I ended up with a final image that wasn't mediocre at best. This is not a good outcome for a camera that has as its major selling point the ability to refocus so that you can avoid bad pictures.

In addition there were aspects of the hardware that bugged me. The biggest was the LCD. The small dimensions were inevitable given the industrial design but the quality was less than stellar. It was dim and had poor viewing angles which made the camera difficult to use. My other hardware related gripe is the lens cap. It never stayed on as the magnet was weak. Consequently I was always losing it. Having said that, I loved the concept and the technology and have been looking forward to Lytro's second generation camera for awhile now.

Enter the Illum, a product that on paper promises to be a significant improvement over its older sibling. The design is slick and modern looking with a definite nod to digital SLR's.

The lens is a permanent part of the body and features an impressive 30-250 mm zoom range with a constant F/2.0. What does that mean in layman's terms?  Basically you get everything from a fairly wide angle to an 8x zoom with excellent light capture across the entire range. The ability to capture light is important as it relates directly to the quality of the picture. This is true of any camera but even more so in the case of light field photography.

Our eyes and brain are a great team. They work in tandem to create a visual experience that is generally smooth and glossy. Normal camera's don't have a sophisticated human brain doing real time processing which is why it can be difficult to get a good picture.

Getting a well focused image requires an appropriate depth of field, (AKA focus point) and either a whole lot of light so that the exposure time is short or a tripod and long exposure time. The Illum doesn't have the human brain but it does have a whole lot of smarts and technology built in that should make it easier to take good pictures.

The first advantage the Illum has over most cameras is that 2.0 F-stop rating. The thing to know about F-stops is that the lower the number the faster the lens. Put another way, as the number decreases the lens is capable of letting in more light because it can open wider in a given period of time. Normally that is a bit of a trade off as more light means a shallower focus range. Large F-Stop numbers mean that most or all of a picture you take will be in focus while small F-stops mean you'll have a steadily narrower focus range as the F-stop number decreases. This isn't a problem for the Lytro as capturing the light field allows an image to be rendered that is in focus over a much wider range of distances. In effect you get the wide depth of field advantage of a high F-Stop but with the high light capturing capability of a much smaller F-Stop which should translate into better quality pictures in situations such as sporting events where fast shutter speeds are needed.

The Illum's 40 mega ray censor will capture roughly four times the light rays that the original did. This in turn translates to 4 mega pixel 2D images. That 4 mega pixel export number is likely a compromise that provides reasonable output in a wide range of scenarios. Macro images and images a very limited depth of field could likely be rendered at higher resolutions with good results as the light rays captured would originate from a much narrower depth of field range and thus provide more data(light rays) at a given focus depth with which to render an image. Of course the inverse is true as well. The wider the available focus range the less data will be available at a given focus point to render from. This may explain why Lytro images can look soft. Lytro basically has two choices when they don't have a lot of data at a given focus point. They can interpolate between available light rays or look at light rays that may provide additional information but not be ideal for a given focus point. In all likely hood I suspect they do a bit of both.

The LCD may be the biggest upgrade of all though. As I mentioned above, the original Lytro's LCD was... sub optimal. The dimness, limited viewing angles and small size meant that I was often shooting blind. The Illum's much larger screen and ability to tilt will inevitably lead to a better experience. How much better remains to be seen but I'm fairly optimistic. My Cannon EOS 70D has an LCD that rotates and moves in a lot of ways that the Illum's won't but it won't tilt back without rotating it 180 degrees out from the body. This provides a similar but not identical experience and after trying it out I think I'm going to like the Illum a lot. The best shot is often taken from lower than eye level, particularly when you're tall as I am. Being able to look down and easily see the framing for the shot is very useful.

The UI on the original Lytro was spartan. That was because of the tiny touch screen and  limited processing power. The Illum's Snapdragon 800 processor has four cores which will enable a much better user experience. One feature shown in the pre production models is the ability to visualize what will be within the refocusing range. That alone is worth the price of admission. It was always frustrating to me when I'd take a picture, load it into the Lytro management software and then not be able to refocus as I wanted.

Of course the big question is will all of this be worth four times what the original Lytro cost? I pre ordered mine and as an owner of the first generation camera I got an additional ~$250 discount. That was good enough for me to pull the trigger so I'll be able to explore first hand what this camera does in another month or two. I have some thoughts on the pricing that I'm going to reserve for the next part of this series.
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  1. This comment has been removed by the author.

    1. Did you find an answer to your question Danny?

  2. This comment has been removed by the author.

  3. Hello Mike!
    The 4 megapixel resolution is interpolated?
    I am suspicious that it is 2.8 megapixel


    1. Danny,
      In a sense all Lytro pictures are "Interpolated" since they are just a collection of light rays. The Lytro desktop software takes those light rays and based on the desired focal depth and other factors it renders an image.

      I'm not sure why the images I exported came out 2312x1736. It could be operator error on my part, a bug in the Lytro Desktop software or a real limitation.

      I'm strapped for time right now but will look into it as soon as I can. It might be a few days. :-(

    2. Actually I got a few minutes to take a look and I'm very confused. I think this is a problem with the Lytro Desktop software. Images from the original Lytro camera default to 1134x1134 which is just under 1.3 megapixels. My memory tells me that they used to export at the slightly lower resolution of 1080x1080 so that seems to have been increased slightly.

      Illum images on the other hand default to exporting at 2022x1404 which is only about 2.8 megapixels as you note.

      The Illum has nearly 4x the light ray capturing ability of the original Lytro camera. It seems odd given that and what Lytro has said about the Illum that it is only exporting at 2.8 megapixels.

  4. Ok, but better watching the "Lytro Desktop Appclication" software exports a single image jpg with 2450x1634, obtaining the 4megapixel. (Export -> Image)
    This image I refer to as interpolated, based on the 2.8 megapixel via software.

  5. Perhaps. The odd thing though is that the first generation Lytro images will export to LFR at nearly half that resolution (1.3MP in spite of having just over 1/4 the light rays that the Illum has. It's very odd and feels like a bug to me.

    Time will tell.

  6. Finishing our pleasant conversation, so I plan to wait for the launch of Pelican technology, which can
    amazing 8 megapixel.
    Thanks and see you one day!

  7. I've read a bit about Pelican. Their approach sounds interesting but at the end of the day they are building their exported image from interpolated data as well. The samples I saw looked reasonably good but just looking at megapixels is only a small part of the equation. Even side by side comparisons of the same scene are a bit iffy. For instance the perspective shift on the sample Pelican images seemed very limited compared to what the Illum can do.

    It's nice to see multiple companies working in this space in any case. Competition is always good for the consumer.