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No Easy Fix for 3D Crosstalk

One of the more obvious downsides to the current generation of 3D home theater is an artifact known as crosstalk (or “ghosting”), in which picture information meant for one eye intrudes into the other eye’s view. This results in a ghostly double-image around objects in the frame. It can be incredibly distracting when it happens. After a recent bout of terrible crosstalk on a couple of Blu-ray 3D discs, I thought that I might have figured out a potential way to reduce or eliminate the artifact. Alas, I found no easy cure for this 3D malady.

The exact causes of 3D crosstalk are widely and inconclusively speculated. Some displays seem to be more prone than others. Reportedly, DLP TVs and projectors are virtually immune to the problem, while LCD screens typically have it worst. My JVC D-ILA projector supposedly falls somewhere in the middle. Yet the content being watched also seems to play a part. Some movies or videogames exhibit stronger crosstalk artifacts than others, and often on a wide variety of displays. I don’t know of anyone who’s played the PS3 game ‘Killzone 3′ in 3D without complaining about serious ghosting problems during the cut-scenes. So, is it the content at fault or the display?

Recently, I came across the worst case of crosstalk yet while watching the Blu-ray 3D editions of ‘Monsters vs. Aliens‘ and ‘How to Train Your Dragon‘ on my projector. Yet the Blu-ray 3D edition of ‘Cloudy with a Chance of Meatballs‘ (another CG animated movie with a similar visual style) is nowhere near as bad on the same screen. Other than the difference in production studio (‘Cloudy’ is a Sony title, while the others belong to DreamWorks), there doesn’t appear to be anything inherent to the look of one film (stronger contrasts, more saturated colors, whatever) that might exacerbate the problem over the other. Perhaps this has something to do with one studio authoring the discs with more of a parallax offset between the right and left eye images than another studio? That sounds plausible, right?

ghosting No Easy Fix for 3D CrosstalkAt the same time, some viewers have watched the ‘Monsters’ and ‘Dragon’ discs without noticing much crosstalk. In fact, I cued up some of the worst scenes and played them on my Vizio passive 3D TV, and the ghosting artifacts (if not quite gone) were greatly lessened. This would seem to point back to the display being at fault, not the discs.

In either case, what can be done about this? I thought that I had come up with a possible solution. Emphasis on thought.

It seemed to me that crosstalk must be the result of improper convergence of the left and right eye views. If the parallax offset between the two is too wide (or too narrow), the 3D glasses won’t sync to the image properly and direct the correct image to the correct eye. So, what I wanted to do was adjust the parallax by either converging the two views closer together or wider apart.

Some 3D TVs offer a “depth” or “strength” adjustment setting that will manipulate the parallax offset between the left and right eyes. Unfortunately, neither my 3D projector nor 3D TV has this feature. Nor does my OPPO BDP-93 Blu-ray player. However, Panasonic Blu-ray players (such as the model that E. wrote about a couple months ago) do have such a feature. Panasonic calls this the “3D Effect Controller.” When I reached out to some contacts at Panasonic for an explanation of exactly what this setting does, I received the following response:

3D Effect Controller allows you to moderate the leaping effects of 3D content. It adjusts the depth of objects by independently equalizing the left and right view of the picture. 3D effect controller also lets you shift the picture back and forth. Overall, this feature helps those who are uncomfortable or not used to viewing content in 3D.

While this feature wasn’t designed with my particular need in mind, the part about “independently equalizing the left and right view of the picture” pretty much sounded like what I wanted. If I could use this to tweak the parallax of a Blu-ray 3D image, I hoped that I would converge the eye views better and eradicate those pesky ghosting artifacts. And since the Panasonic DMP-BDT110 can be purchased for just over $100, this didn’t seem like too big of a risk if it didn’t work.

Well, I bought the machine and played around with it quite a bit. My results were unfortunately very mixed. On the worst crosstalk scenes of ‘Monsters vs. Aliens’ (and there are many), I could converge the parallax to eliminate ghosting on foreground objects but not background, or vice versa. There was no sweet spot setting that converged all depth planes. As shots changed or characters moved forwards or backwards in the frame, a ghost-free image would turn into a ghost-filled image. The default setting seems to be to prioritize convergence of the foreground, which is least distracting, but also basically the same as the results from my OPPO player.

While I was at it, I also tried out the Panasonic’s 2D-to-3D conversion feature on some standard Blu-ray discs, and found it to be pretty useless. All it did on either of my screens was make the whole flat 2D picture look like it was inset a few inches behind the frame of the screen. It didn’t create any depth mapping or pop-out within the image other than that.

The experiment a failure, I wound up returning the Panasonic player. I’m still searching for that magic cure that will solve my 3D crosstalk problems. Or, failing that, a concrete explanation of what really causes them would be nice.

[Banner image borrowed from this page. Walking girl comparison image borrowed from this page.]

13 comments

  1. All of this can be avoided just by refusing to watch 3D movies. I’m still rocking my 2008 (2D) Samsung plasma, with no plans to ever “upgrade” to 3D.

    • Drew

      An easier solution would be to just buy a television or projector that doesn’t exhibit any crosstalk during 3D viewing. There are several that are capable of this.

      I witness absolutely zero crosstalk on my screen, unless it was there natively due to a shoddy conversion, or some other similar issue.

      • Josh Zyber
        Author

        Since 99% of my viewing will continue to be in regular 2D format, the JVC projector is about as good as you can get in that regard. I’m not willing to sacrifice 2D picture quality to get a new projector (such as a DLP) with better 3D but inferior contrast. What I’m looking for is a solution that will improve that 1% of 3D viewing on my current display.

  2. Rich87

    I’ve heard cases of crosstalk being elminated on some displays by simply connecting an HDMI 4.1 high speed cable. I’m not sure which cable you use but it could very well be a bandwidth issue.

    • Josh Zyber
      Author

      I don’t put a whole lot of stock in magic cables, especially not magic digital cables. Either HDMI transmits the signal or it doesn’t. There’s something else at fault here. I use the same cables with my Vizio TV, which has less crosstalk on these discs.

  3. That1guypictures

    The crosstalk is caused by the shutter speed of the glasses, not the display. If the lens of the glasses dont close fast enough (dont get dark enough) you see too much of the other eye’s view). This can be seen strongly on the 2010 Panasonic sets. They are on their third gen glasses and each years glasses have made crosstalk issues lessen. Passive sets tend to have the smallest amount of crosstalk. Samsung 2011 plasmas have The least crosstalk, followed by Panasonic.

    • Josh Zyber
      Author

      I have a pair of JVC’s glasses that were made for the projector, and also a pair of XpanD 103 universal glasses. The ghosting problem is about the same, but that’s probably because XpanD makes JVC’s glasses as well. If there are better universal glasses solutions out there that might help with this, I’d be interested to find out what they are.

      The other thing that confuses me is that some owners have reported that the crosstalk problem on JVC projectors gets worse as the lamp ages and dims. I may be experiencing this as well. In the early days, I hardly ever saw crosstalk on any discs. But I don’t understand why the lamp brightness would affect crosstalk.

    • Drew

      That’s not true at all. Crosstalk is virtually non-existent on any high-end plasma set, but still quite prevalent on most LCD sets regardless of how “top of the line” they are.

      Crosstalk is caused by the image displayed not being resolved fast enough. If the set or projector take longer to resolve both images than your brain is capable of doing so, one image will converge into both eyes, creating crosstalk.

      Plasma sets resolve the image exponentially faster than LCD sets. This is why they are so good at eliminating cross talk. This same theory is the reason why DLP sets and projectors do such a good job at eliminating crosstalk. It’s also the reason why passive sets exhibit much less crosstalk.

      Passive sets aren’t really showing two separate full resolution images. They are showing one image and using a film retarder coating on the screen to essentially separate that image into two. This means that they don’t have to actually try to resolve two separate images, and send two separate images to each of our eyes. Hence, the reduction in crosstalk.

      Passive sets are riddled with jaggies and horizontal lines, and also make 3D viewing extremely soft and less detailed than active sets do. I tried two high-end passive sets this year for a secondary home theater. I enjoyed not seeing virtually any crosstalk, but the image was just too soft and low resolution for me. I returned both of them, and ultimately went back to a 2011 active set.

      If you prefer 3D viewing with less crosstalk, but an image that looks more like standard definition, passive sets may be for you. If you prefer a crisp detailed image with little to no crosstalk whatsoever, go active, and stick with a high-end plasma television, or DLP TV/DLP projector.

  4. Tony

    I think what Drew says about the superiority of plasma/DLP for 3D viewing is correct. I’m curious how much the new 480Hz LCD panels will improve things, but I don’t expect them to be as good as plasma or DLP.

    Although it sounds a little crazy, placing a 3D DLP projector like the Optima HD33 next to your JVC for 3D viewing only might give you the 3D quality you want.

    • I am not sure that will really fix the issue – otherwise we could say that 240Hz televisions display a vastly superior picture to 120hz on 3D. That is sadly not the case, LCDs suck on crosstalk.

      I think Drew really hit the nail on the head – it has all to do with how fast your display can refresh the picture. Early LCDs (I am talking about back in the 90s and early 2000s, so mostly computer screens) were bad about ghosting on 2D. No one serious about quality would watch video on an LCD back then, no matter how much clearer the picture was than CRTs because of this ghosting issue. Most televisons can now handle 24FPS just fine without ghosting, but even as few as a couple of years ago, if you were watching sporting events or something on a LCD television that had 60fps, you might see very slight ghosting. You rarely see that anymore. However, on an active-shutter 3D set, if that image lingers on the screen just a fraction of a second too long, this could cause crosstalk. And, with a 3D image having to redraw the picture 48 times a second instead of just 24, I can see that some cheaper screens may have this issue.

      Probably the best way to test out this theory is to see if there is more motion, or contrast between colors or brightness of colors on movies that exhibit heavy crosstalk.

      • BTW, so I don’t think 120 Hz sets actually refresh the screen 120 times a second. True, that is what they are supposed to do, but the quesiton is, when you deliver the next frame to the screen, how long does it take the screen to take off the previous frame – ie – how fast do the pixels actually resolve. Its possible that, even if they are using a fast processor to do the frame infering or whatever its called (the term just slipped my mind), that the actual screen cannot refresh that fast. Therefore, a Higer Hz on a televion could actually cause a WORSE picture, resulting in some very mild ghosting. It may not be noticible on 2D stuff, but could make a difference on 3D stuff. If the option is available, I would try turning it off for 3D viewing.

  5. 3D effects are going to have the same issues as we experienced with audio sync and the fix was to add a delay timer. If the shutters on your glasses are too slow or have a mismatch with the transmitter, boom, ghosting. Another reason I am not an early adopter of the 3D format-kinks are still being ironed out.

  6. I believe that the ghosting or crosstalk issue is a studio problem because in my Samsung 9000 55″ not problem with some movies. e.g. Resident Evil After live the best movie but not the same about Tron but Toy Story 3 one of the best and another hand Megamind some minor issues.