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Monday, August 06, 2007

Better Than High Definition

New high-contrast displays could provide more-realistic images.

By Kate Greene

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Pictures that pop: Above is a high-dynamic-range (HDR) image that was created by combining a number of exposures.
Credit: Erik Reinhard
Multimedia
•  See examples of high-dynamic range images.

High-definition displays are increasingly popular. More and more people are experiencing high-definition movies and television in breathtaking color and detail. But another technology, called high-dynamic range (HDR), is on the heels of high definition, and some experts think that it could be a quick successor. Whereas high-definition displays pump out more pixels, HDR displays provide more contrast. In other words, on an HDR display, the brightest whites are hundreds of thousands of times brighter than the darkest blacks; the contrast is key to making images on such a display appear more realistic. "A regular image just looks like a depiction of a scene," says Roland Fleming, a research scientist at the Max Planck Institute for Biological Cybernetics, in Tübingin, Germany. "But high-dynamic range looks like looking through a window."

Fleming, whose recent research on high-dynamic displays is being presented at SIGGRAPH, a graphics conference held this week in San Diego, suspects that this realism will draw people to the technology. And recently, manufacturers have started to pay attention to HDR. Major companies such as Phillips and Samsung have demonstrated prototypes at trade shows. Jason Ledder, a representative for Samsung, says that the company is "doing a variety of research and trying to figure out when and where to incorporate [HDR] into products."

Earlier this year, Dolby bought BrightSide Technologies, a startup based in British Columbia that developed a novel HDR display capable of four hundred times more contrast than a conventional monitor--closer to what the human eye can perceive. While a traditional liquid-crystal display is illuminated by a single white backlight, a BrightSide display is illuminated by an array of tiny white light-emitting diodes (LEDs). This means that individual LEDs can be turned off or on, increasing the darkness or brightness to various parts of the liquid-crystal display. Neither Dolby nor the other companies are providing specific timelines for a product, but Fleming has heard reports that displays could be available, for a few thousand dollars, within a year.

One of the problems with introducing a new type of display, however, is overcoming the perception that there won't be any content that will take advantage of its potential, Fleming says. This is something that has plagued the market for high-definition displays: many people are waiting to buy a high-definition TV until there is more content, and providers are slow to churn out high-definition content until more people have the displays. Many experts believe that the same issue could be a challenge regarding HDR products.

However, the research by Fleming and his colleagues at the University of Bristol, in the UK, and at the University of Central Florida suggests otherwise. "The key questions that everyone's been raising," he says, "are how [HDR] is going to make the transition and how it is going to show a regular image." Usually, he says, regular images can be processed using difficult-to-engineer software that adds contrast. His team's original plan was to determine people's perception of contrast on HDR displays to see how much extra information needs to be added to a regular image to make it appear as an HDR image on an HDR display. To the researchers' surprise, says Fleming, they learned that they didn't need complicated software at all. They surveyed people viewing low-contrast and high-contrast images, both on an HDR display. When the low-contrast images were processed with simple software that amplified pixels, the images were perceived as high contrast. In fact, Fleming says, the average person couldn't tell the difference between the low- and high-contrast images, and all the images looked significantly better than they would have on a regular display.

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Comments

  • Up hill battle
    sculptor on 08/06/2007 at 3:01 PM
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    No current digital sensor exists that can come close to recording the dynamic range of the human eye. I suspect that such a sensor won't be developed any time soon because if there was an obvious technical solution digital camera makers would have embraced it already.
    Rate this comment: 12345
    • Re: Up hill battle
      opticsdude on 08/06/2007 at 4:58 PM
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      1
      I agree that current sensors aren't operating with the dynamic range of the human eye, but I think the end of the article was suggesting a new configuration to simulate that dynamic range.  By taking a sequence of images with different lighting conditions, you could bootstrap together an image with a higher dynamic range.

      It sounds hard, but doable for still photos. It sounds crazy hard for full motion video (30fps)  
      Rate this comment: 12345
      • Re: Up hill battle
        CSGuy on 08/08/2007 at 2:33 PM
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        2
        Its seems like there is an easier solution to "simulate" the dynamic range with film other than re-shooting the same shot.  A single sensor can't be used, but perhaps multiple sensors each used to sense different ranges.  Then software could be used to combine the data into a single HDR image.  New camera development would be needed, but it would be less expensive that re-shooting every shot.

        Any film maker knows that it would nearly be impossible to get the same shot twice.  The logistics of this would cost too much time and money.  No wonder film makers aren't starting to do this.
        Rate this comment: 12345
    • Re: Up hill battle
      GraemeR on 08/07/2007 at 9:01 PM
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      1
      Synthetic digital images for videogames or animation would not have that limitation and could use the full dynamic range immediately.
      Rate this comment: 12345
    • Re: Up hill battle
      Wayne on 09/14/2007 at 10:19 AM
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      2
      I glanced through the article on my way to somewhere else.

      They are crazy, I walked by an Flat panel TV the other day, with an picture of the sun blazing through it, and my eyes stung, thats quiet high range enough thank you.  Even if we have an billion to one contrast ratio, our eyes are limited to around 8 bits (linearly).  We like our images to be just nice, otherwise sunglasses would be an bit less popular.

      High Dynamic range is useful in processing and production.  Sometime ago, I estimated that an reasonably accurate 16bit(*3=48bit) pixel capture would give enough range of capture to be able to film an scene without much regard to lighting and adjust the exposure afterwards (and with 3D algorithms, the lighting at any point).  In games production, and display processing, the higher bit depth helps prevents certain artifacts and contributes to an more accurate rendition.

      As stated before, already displays are many thousands to one in the consumer space, and brightness levels are excessive.  We don't really need higher contrast, unless we want an sunglasses in hand virtual simulation (i.e. yes like Star Trek)

      This article seems an bit strange, apart from the above, dated, led backed displays have been out for years and many consumer televisions with it are said to be coming out.  He says that people cannot pick the difference between genuinely high contrast, and low contrast amplified, but we need genuine HDR content because it looks more stunning.  The pixel amplification circuit seems to achieve, in reverse, what we do with contrast and brightness controls on high contrast footage on bright high contrast displays.

      I am an member of the digital cinema camera projects over at dvinfo.net alternative imaging forums.  About cameras not been able to record an contrast range as much as the human eye, I submit the following:

      http://www.hdrc.com/hdrctech.htm
      http://www.planet82.com/korean/product/smpd_01.asp
      http://www.altasens.com/
      http://www.cypress.com/portal/server.pt?space=CommunityPage&control=SetCommunity&CommunityID=285&PageID=552&drid=67900&shortlink=&r_folder=&r_title=&ref=drs

      Some can deliver the range at descent quality.  About 16bit pixels, an few years ago altasens cameras had been reported to have gone up to 96db s/n ratio.
      Rate this comment: 12345
      • Re: Up hill battle
        Wayne on 09/17/2007 at 8:42 AM
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        2
        I went to an store to see an LG 56dc1d DLP rear projection set today.  The set, I have seen in times past, probably the best projection set I have ever seen, and is better than many LCD panels of it's day.  They had an new LCD Sharp 10000:1 contrast, very bright, 4 color system for an more normal color pallet (LCD's tended to be very deficient).  I could see that normal daylight scenes looked much better on it compared to the other LCD panels because of the extra brightness, even though highlights and snow scenes were washed out.  But I prefer the rear projection, even though it has 350cd output, and 2500:1 contrast, simply because the color range of the screen was more lively, enough to make it look as good as the brighter Sharp.  If the sun, or bright reflections had been on the Sharp, the result would have been more unpleasant.

        http://au.lge.com/products/model/detail/tv_rearprojectiontv_dlp_56dc1d.jhtml
        Rate this comment: 12345
  • close
    TMacshane on 08/08/2007 at 2:33 PM
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    3
    Close but no cigar, but then again every persons' visibility varies so it is very hard to pinpoint what would be considered the perfect clarity. What may be crystal clear and comparable to the quality of the human eye to some, may be blurred and choppy to another. Far fetched, but wouldn't it be something that there was a device to adjust television, computer monitors, etc. to people's eye needs (almost like a trip to the eye doctor who will slap on a range of different spectacles on you for diagnosis). I realize you can adjust contrast, brightness, etc. on screens, but you can't adjust for people with far/near sightedness, those that need eyeglasses, etc. Realizing it might be like having to make the settings on these machines mimic a giant pair of adjustable eyeglasses, is it possible?
    Rate this comment: 12345
    • Re: close
      CSGuy on 08/08/2007 at 3:04 PM
      Posts:
      2
      I think the ultimate goal, as it was put in the article, is to be able to look at a display as if you were looking out a window.  With that in mind I think that it is possible to approach that "clarity" regardless of how someone actually views the image.  In other words, I look out my window and the subjective image might appear different to someone with different sight.  However, that doesn't change what is being viewed; the object doesn't change.  I think if the display reached the level of accurateness as whatever light waves are coming through my window then it doesn't matter how the subject perceives it with sight imperfections. 
      Rate this comment: 12345
  • A photographer's view
    Tysto on 08/10/2007 at 12:31 PM
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    16
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    3/5
    Jeez, people, this is basically just about making superbright monitors that still can display deep blacks. That's perfectly achievable. Digital camera sensors continue to get better and will soon allow us to avoid having to choose between exposing for shadows or for highlights: it will all be captured. That's also perfectly achievable (RAW format is already a form of HDR: http://www.flickr.com/groups/raw2hdr/).

    The main question this article addresses is how today's images and code will be displayed on an HDR monitor, since "pure white" in HDR is much brighter (uncomfortably brighter) than it is on today's monitors. Web page backgrounds are commonly pure white, but you don't want to have to wear sunglasses to read them.
    Rate this comment: 12345
  • recording
    CountZ3ro on 08/15/2007 at 10:12 AM
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    2/5
    A technique for recording has already been worked out a year ago by a joint Hungarian-Japanese team. I saw the presentation at a conference. Demo pictures included photos taken of an open book closely lit by a lamp, when normally the text would be unreadable. The results were very nice. The only problem with the approach was that the recording of a single picture took seconds...
    Rate this comment: 12345
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