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World's First Full HDR Video System Unveiled
Zothecula writes "Anyone who regularly uses a video camera will know that the devices do not see the world the way we do. The human visual system can perceive a scene that contains both bright highlights and dark shadows, yet is able to process that information in such a way that it can simultaneously expose for both lighting extremes – up to a point, at least. Video cameras, however, have just one f-stop to work with at any one time, and so must make compromises. Now, however, researchers from the UK's University of Warwick claim to have the solution to such problems, in the form of the world's first full High Dynamic Range (HDR) video system."
If you read the article, the author mentions both the folks in SF who did HDR video previously as well as the fact that the Warwick team have indeed developed a new HDR display for their system.
Also mentioned is that the new system generates 42GB/minute of data to capture images with 20 exposures per frame. My backup nightmare just grew large fangs!
Nothing interesting to say...MUST...NOT...REPLY...ohtheheckwithit.
Speaking of 3D rendering, most of them output HDR which would be awesome to see without being tone mapped!. (LuxRender has built-in Reinhard tone mapping) And since we are on the topic of HDR.. this is what it is NOT http://www.cs.bris.ac.uk/~reinhard/tm_comp/flickr_hdr/The%20Problem.html (Reinhard discusses the blown out tone mapping heavily prominent on flickr)
It's because it's not pleasing to the eye. 60fps movies look very strange...like home videos. The 24 fps is what gives them that "movie look". If you look at some example vids from some of the newer consumer cameras that can do 24 and 60fps...you'll see the huge difference it makes.
The summary is just plain wrong, and the article may be as well. First, there seems to be some massive confusion between f-stops and dynamic range 'stops'. An f-stop is your aperture setting, and is part of the control that determines how much light gets into the camera. If I go out and desire to take an HDR picture of something, the f-stop is the last control I will use in setting each exposure. The f-stop has the side effect of changing the depth of focus, thats covered in photography 101. If you change that in a set of pictures, some things will be in focus in one frame, while out of focus in others. It doesn't look that nice once post processed.
On the other hand, a dynamic range stop is just notation for double the amount of light. If someone said "That film has about 9 stops of resolution" you would know that physically the brightest area on a picture would have 2^9 times as much photonic flux. Or you would be more camera focused, and know that the film would only record detail in the 4.5 stops above, and 4.5 stops below what ever you set the exposure for. An object 5 stops brighter than what you were focused at would be a washed out blur, and something 5 stops darker would be total shadow. A quick run through google suggests that Kodachrome, the legendary film, could record only about 8 stops dynamic range. The human eye can pick up something closer to 24 stops. GP's Red camera records 11.3 stops. Some people will claim that a digital camera gets as many stops as bytes, but that is only with the analog to digital conversion is logarithmic, and so is the display it is shown on. Mine runs about 7 stops, depending on other settings.
So, what's that got to do with this camera? I suspect what the article meant to say is that the camera captures 20 stops of data at 30fps. Better than the Red, better than almost any film in existence. It is doing the same thing in a single shot that other cameras do in several. All that will mean is less blur in HDR video, since subjects won't move irregularly between exposures. One would still have to tone-map the output down to a range that it can be displayed for printing, projection, or dvd.
Unless you have an HDR screen, this would require an automatic tone mapping. The thing about automatic tone mapping is that you have to decide what intensity information to throw out since you only have 256 values that you can display. For instance, using a 14 bits per color channel canon DSLR sensor, if you want to look at the image on your screen, this means you'll have to thrown out 98.4% of your intensity values. It is extremely important which values you decide to throw out, especially considering there's usually a subject or subjects in a photo that you want to keep visible.
By the way, this 14bits gets you about +/- 2 stops...the camera they're talking about gives you 20 stops...that's an *incredible* amount of intensity information (giving the file size). Really this is more of a solution for filming a scene once and not having to worry about if you camera exposure is set correctly, which *is* extremely valuable.
Now, viewing HDR movies? Not in theaters with any sort of current projection technology with reasonable ticket prices. The projection bulbs would have to go up probably 20 times in brightness, keeping similar crappy projection theater black levels. And, how do you deal with the ambient light coming off of your now incredibly bright white screen and bouncing off of the audience? At home, do you really want a tv that bright? From this bit-tech review, "The light from the box was so bright, or indeed, was of such great contrast with the surrounding area, that it almost hurt to look at.".
I would like to correct a mistake prevalent here and in the news summary: common camera's do NOT get 1 (or 2) stops of light information (the difference between black and white). In fact, camera's like the Canon 7D have about 11 stops of dynamic range [source] and professional video camera's like the Red One have about 13 1/2 stops of difference between black and white [source]. Still, as X stops means 2^X times the light difference, going from 13 1/2 to 20 stops is a pretty huge deal.
Another misconception: the amount of bits per channel only indicates precision, not dynamic range. Of course, when the researchers in the article created a 20 stops camera, they needed much better precision to get similar quality in the same range as the current camera's, which leads to the quoted 42 GB per minute uncompressed video stream.
(Please note: DSLR camera's like the Canon 7D can detect and save more dynamic range than is apparent from the JPG's they create and the extra information is saved in the RAW file, which allows you to change exposure settings at least 1 stop in post processing without (noticeable) drop in quality.)
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