HDR Video a Reality

akaru writes "Using common DSLR cameras, some creative individuals have created an example of true HDR video. Instead of pseudo-HDR, they actually used multiple cameras and a beam splitter to record simultaneous video streams, and composited them together in post. Looks very intriguing."

Comments

The holy grail of camera tech....

[Above]

HDR

Focus Stacking

Panoramic Stitching

All in the camera, all 1-button easy to use, and all at once.

Re:The holy grail of camera tech....

[Prune]

You forgot about full lightfield capture. This can be done with a single camera using ultra high resolution and a microlens array (or alternatively, an array of a very large number of tiny cameras). Think single camera, single shot capture of depth (3D) and all focus planes. Then you can reproduce the full 3D and multiple focus depths (as in, the eye would have to focus at different depths) on a flat display with microlens array covering it (again, need ultra-high resolution since focal depths and parallax viewpoints are discretized to the pixel number covered by each micro lens).

Re:The holy grail of camera tech....

[Prune]

You don't need aperture at all if you use a microlens array to do integral photography. On top, you get full depth (3D) and capture all focal lengths, including the focal depth information. All in a single shot. Just need an ultra high resolution sensor--or, instead, an array of many small cameras (works just as well, and no need for perfect alignment as that can be finessed in software). You capture a full 4D lightfield (light can be parameterized as the two pairs of coordinates of a light ray crossing two infinite planes), i.e. miss no optical information whatsoever other than your diffraction and wavelength limits.

HDR?

[afaik_ianal]

Can anyone give a brief rundown on what HDR is? I know it stands for "high dynamic range", but as someone who knows nothing about photography, it means nothing to me. What it has to do with overexposure/underexposure (to which the video refers)? Why is it harder to do with video than still images?

Re:HDR?

[plover]

One problem I realized after watching the scene with the guy is the video compression artifacts can be different between the two cameras. Even if the sensors were perfectly aligned with each other and the optics, the MPEG compression could be different because the values at each pixel will still be slightly different due to the differences in exposure levels. Different pixel values can cause different compression schemes to be invoked in each block, which will result in weird combinations of aliasing. I think this may have been partly responsible for the shimmer on his denim jacket.

Very impressive!

[WilliamGeorge]

I've been a long-time fan of HDR photography, and was just thinking about ways that HDR could be implementing in video camcorders as well. Personally I'd like to see a correctly-exposed stream mixed in with the other two, as is common in photography, but even without that the effect is pretty darn cool.

By the way, in case any camcorder manufacturers are watching, consider this idea: make a video camera with three (or more) times the required number of sensors for the resolution you want to record at. Set the logic in the device up to use three unique sets of sensors inside to pick up three different sets of images, at differing exposure settings. Then have them saved separately so that they can be integrated later on for various editing effects - or have a mode where they are integrated on-the-fly for easier use by non-professionals. I imagine it would be expensive to make such a complex sensor and camera, but it might be easier to manage than multiple cameras as the folks in the article did.

Franken/3D cameras

[gmuslera]

With frankencamera you could do HDR and a lot more things in an "intelligent" camera with software. In fact the first implementation in a mass consumption device was in the N900, it takes several photos, regulates exposition and other parameters to make that photo in a more parametrizable way that the iphone could do. But not sure if that would be enough for HDR video, if needs that the input, in real time, have different something at hardware level. In that case maybe something like this 3D camera would be needed. And could give some meaning to such devices... not only shooting in 3d, but in HDR video.

Re:a text C&P from the article

[yoyhed]

It's the other way around.

Even though we call it high dynamic range in videos and photographs, it's actually just compressing all the extra information from multiple exposures into a LOWER dynamic range, so we can manipulate/display it on our 8-bit screens.

Games, however - such as the Source engine after it got the HDR update with Half-Life 2: Lost Coast and Day of Defeat: Source, actually do increase the dynamic range of a scene beyond what your monitor can display. They underexpose and overexpose parts of the scene when transitions between light and dark places occur, just as your eyes would before they adjusted to the new light, or as a video camera would depending on what exposure the videographer chose. This makes it look more realistic - just take a look at a bright outdoor scene in Half-Life 2: Episode Two and check out how shiny objects in the sunlight have blown-out highlights that gleam brilliantly, and then look at the same scene in the original Half-Life 2, where that object would look flatly-lit and fake. The "non-HDR" looks more fake because the dynamic range is compressed so you can see all the detail everywhere, which also gives it that flat "game" look.

Of course, that last part is just my opinion - but I believe that in order to look more realistic, CGI needs to simulate the behavior of traditional cameras with a lower dynamic range (or that of your eyes before they've adjusted properly to bright/dim light). The everything-is-exposed-properly, compressed-dynamic-range look just appears fake to me, even though my eyes could probably perceive that range at the actual scene. I'm not sure why.

I did this on Fast and Furious/Tokyo Drift

[Thagg]

For the third of the Fast and Furious movies, we had to film at night in the spectacular Shibuya Square in Tokyo, with its many animated billboards and video screens. I really wanted to get an HDR film of the billboards.

For the driving green-screen sequences of the film, we had built a plate to mount three cameras, at 0, 45, and 90 degrees, to shoot panoramas driving down the street. To get the nodal points closer together, we had the cameras facing toward each other, with the lenses almost touching. It worked wonderfully.

By taking the center camera out, and replacing it with a beam-splitter, we had a down-and-dirty HDR rig using the other two cameras. Now, this was HDR on film, not video -- but film already has a very high dynamic range -- so two cameras with very different effective exposures gave us a tremendous dynamic range. In the 'normal' exposure all of the brighter signs were blown out, but on the beam-splitter camera you could see all the details of the structure of the lighted billboards. Quite cool.