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MLXXX

3D and projectors

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For many years, stereoscopic 3D has been close to my heart.  I thought it not a bad idea to start up this thread with its primary emphasis on projectors and 3D. 3D TV sets are no longer being made, but, thankfully,  3D projectors are!

 

Virtual reality headsets are becoming more popular but they tend to offer wide vertical and horizontal viewing angles and the actual resolution for watching a 3D Blu-ray at its required vertical and horizontal viewing angles generally turns out to be poor. (There are some promising developments in 3D cinema headsets and in a year or two it might be a good solution to use these for high quality 3D viewing on an aircraft, or in other situations where only one person is viewing the 3D material.)

 

In another, current, thread there's been discussion about the 3D performance of a specific new projector, compared with specific older 3D projectors, and a specific 4K passive 3D TV. That thread is: 3D performance on JVC DLA vs BENQ DLP vs LG OLED?

 

Interested readers might prefer to have a look at that thread first, before continuing here.

 

I thought I'd kick off this new thread by giving a broad reply to a recent post in that other thread.  Here goes...

 

 

On 09/01/2019 at 5:10 PM, PKK said:

When I first got my W1070 in 2013 I found its 2D performance decent for the price but 3D is pretty awful indeed. Its 3D support is very limited and needs some weird resolution and frequency from PC before I can use its SBS or OU function. Only positive about it is zero cross talk of DLPLink.

 

On 09/01/2019 at 5:10 PM, PKK said:

It is at this point that I found a new firmware update for the W1070. I have my doubt initially but go ahead anyway and turns out the upgrade is dramatic. I can't find a fault with its 3D performance anymore. Motion is solid like 2D.

I installed the BenQ firmware update early on, not long after acquiring my W1070, and was then able to use the wider range of video input resolutions. This cheap, entry level, projector provided remarkably smooth 3D for 24fps 3D Blu-ray discs. My main complaint was the rather high minimum black level.

 

Further down the track I changed to a 4K Sony LCD passive TV set with passably good 3D crosstalk performance and a much better black level. Unfortunately after the standard warranty on this TV had expired, it developed an unrepairable screen fault. Sony, to their credit, supplied a brand new set, with HDR capability, free of charge to me. It provided an even further improved black level. Unfortunately the 3D crosstalk performance was poor. (I didn't have the heart to ask Sony for another replacement set. The set was watchable in 3D, but the crosstalk could at times be very distracting.)

 

______________

 

Buying second hand

 

There are lessons to be learned if considering buying a used 3D TV set or projector:

 

1. Passive display screens that use a film-type patterned retarder can give very satisfying 3D by way of displaying Left and Right simultaneously. However even 4K sets using this technology have been known to be subject to quality variations in terms of crosstalk performance. If at all possible a second-hand 3D set using a film-type patterned retarder should be inspected in operation prior to purchase, to assess the 3D crosstalk performance (for viewing from the limited optimum vertical viewing angle range).

 

2. Some projectors do not use a Left Right alternation rate of 144Hz for 24fps 3D movies but 120Hz or even 96Hz. For some people this is a distinct minus to viewing pleasure.  And a certain number of projector models appear to suffer from quality control issues in relation to their 3D performance. If at all possible an assessment with the projector in operation displaying 3D material is desirable. As an example, here is an issue PKK ran into:

 

 

On 09/01/2019 at 5:10 PM, PKK said:

There are many positive reviews of W3000 but rarely any real world user talks about it. I have come across one thread named "BenQ W3000 motion Judder in 3D?" on avforums and the OP was facing the exact same problem as mine and swapped for an epson. It is like a gamble to lock down a good one. I bought my W3000 second hand off ebay for cheap so it does not hurt that much.   

 

________

 

Evaluating performance using side-by-side or top and bottom source material

 

SPORT

 

Some of us still have recordings of the 2010 side by side TV broadcasts in Australia of football matches, or of the 2012 side by side TV broadcasts of the London Olympic games. These broadcasts were at 50 interlaced fields a second.   Shutter glasses typically will slow down to 100Hz if the video material is at 25fps of 50fps. 

 

It's important to understand how limited in quality these broadcasts were and not to blame the projector if the material doesn't scrub up well.

 

This is what to expect:

 

1. Close ups will generally look relatively detailed as the limited horizontal resolution of 960 pixels for the Left view and 960 pixels for the right view is sufficient. However distant shots of players or competitors will tend to look fuzzy.

 

2. The 3D effect will usually work well for close ups of players and competitors. However with a camera view of the entire playing field, adults will often look like children in size. This effect was very noticeable for the coverage of Australian football matches in 2010 with distant shots of players on the field giving the appearance of small boys. In addition, as noted at 1, the images were fuzzy.

 

3. Shutter glasses operating at 100Hz will give a noticeable flicker for bright expanses in the image, such as a view of the sky. The significant time delay between presenting Left and Right when using a 100Hz alternation rate will add a special 3D judder to the appearance of the action where shutter glasses are used.

 

4. Even with passive LCD sets that present Left a Right simultaneously, the underling source video rate of 50 interlaced images a second when deinterlaced to 50 frames a second provides rather indistinct detail for the motion, leading to a breakdown in the 3D effect for those parts of the image that are moving rapidly. (It seems to be easier for human eyes to watch blurry 2D than blurry 3D.)  This issue becomes worse if the display device shows up false images by way of crosstalk between Left and Right.

 

In conclusion, it is no great surprise that broadcasting of side by side 3D television coverage of sport using 2D frames of 1920 x 1080 pixels at 50i, pressed into service for side-by-side 3D,  ground to a halt.

 

Sport at 60i is not as trying to watch with home projectors as the shutter glasses will typically operate at 120Hz, resulting in less flicker, and somewhat smoother motion.

 

CARTOONS, DRAMA, SEA LIFE

 

The net provides some 1920x1080 side-by-side (SBS) or top and bottom material at 30fps or 60fps. This will generally be projected with an alternation rate of 120Hz, a distinct improvement over 100Hz. The limited resolution (limited vertical resolution with the over under (OU) format, limited horizontal resolution with the SBS format) will reduce the visible detail.

 

Cartoons can be very demanding in relation to crosstalk.  They can also involve fast action, which can easily lead to momentary breakdowns in the illusion of 3D.  Dramas on the other hand tend to involve slow action.

 

Nature programs of sea life are particularly well suited to 3D as the speed of movement of sea life is generally slow, and camera distances are often relatively short because of the limited visibility of ocean depths. This tends to keep the clearly visible sea life in the foreground. Also, a school of small fish that looks like a disorganised jumble in 2D can come to life as distinctly visible separate fish when viewed in 3D. The difference between watching in 2D and watching in 3D can be dramatic.

 

__________

 

Brightness - contrast - crosstalk

 

RealD public cinemas have managed to provide reasonably pleasing results with 3D by using low light levels and a polarization alternation rate of 144Hz for 24fps movies.

 

Any attempt to project with high brightness and high contrast at home will place demands on crosstalk performance. In particular, LCD projectors that produce a bright image, may not always change state fast enough to avoid the Left image bleeding into the Right image, and vice versa. 

 

Also any projector that alternates Left and Right at only 120Hz  (or worse, at 100Hz or 96Hz) will tend to look flickery at higher brightness levels.

 

Motion artefacts that human eyes might disregard at low illumination levels can become distracting at high illumination levels because human eyes perceive more quickly in brighter light. (Here's a very technical journal article: Human scotopic sensitivity is regulated postreceptorally by changing the speed of the scotopic response ).

 

It's no wonder to me that 3D discs for the public are limited to a standard dynamic range. With home projectors, it is difficult to achieve sufficiently low apparent flicker and sufficiently low visible crosstalk, at low light levels.  Attempting High Dynamic Range for 3D in a home projector would be asking for trouble!

 

So even if 2D home projectors emerge capable of providing a really solid HDR performance, we should not necessarily expect them to be able to be readily adapted to providing a comparable dynamic range for 3D material, with its special requirements of low flicker and little crosstalk.

Edited by MLXXX

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An aspect of performance  that reviews of 3D capable projectors will not measure, but will report on subjectively (if at all!) is the degree of crosstalk. [It is extremely rare for a review of a 3D projector to include a measurement of stereoscopic crosstalk (or "ghosting").]

 

In our own forum, there was a short  thread in December 2012 on 3D projector crosstalk:

 

In various other videophile forums, owners have either provided photographs of their projector (or flat panel display) displaying a 3D test pattern, or have reported a numeric result for a 3D test pattern.

 

The test pattern commonly used can be seen referred to in the first post of this thread begun in 2010 on avforums.  For my own images below, I used the .MPO file (displayed with my pc Nvidia graphics card, using the Nvidia 3D Vision Photo Viewer). 

 

Why is good crosstalk performance important? Well without it, high contrast parts of a scene may be seen duplicated in lower contrast, offset a little to the left or right. The effect of this can range from being a slight nuisance, to causing viewing fatigue. Also, if severe, it can make the image content in some scenes blurry and/or difficult to make out.

 

1. Poor performance of a flat panel display with a poorly aligned film-type patterned retarder

 

As an example of poor crosstalk performance, here is my own Sony 65" 4K passive 3D TV, displaying the test pattern. The camera was positioned 1.9m from the centre of the screen. 

 

1030159PoorlyAlignedFPR.thumb.jpg.38ce96fe70ef7eeaa14322df28b4db02.jpg

 

The passive glasses were placed a few centimetres in front of the camera. The view through the left lens allows the numbers 20, 21, 22, 23 and 24 to be seen faintly at the bottom of the lens. These numbers ought to appear black.  (On a previous  Sony passive 3D set of mine, these numbers did appear black!)

 

The view through the right lens shows better crosstalk performance. Through the top of the lens you can see 76, 77, 78, 79 and 80 very faintly, and with a blue cast. Given that those are the brightest numbers in the test image, it is not too bad a result to see them reduced to a dull blue.

 

Subjectively, this poor example of a passive 3D film-type patterned retarder screen makes the 3D effect blurry at times, and over a period of time can become a strain to watch. (For me, it is not acceptable.)

 

 

2. Excellent performance of a DLP projector

 

Here is my BenQ W2000 displaying the test image sent to it by my pc at 23.976p (Full HD, frame packed 3D).  The red cast is due to the 3D synchronising flash (and the absence of glasses to blank this out).

 

1030130W2000NoGlassesWithISourceInfo.thumb.jpg.8a64579e0cb20863f5f8f380ca8278fd.jpg

 

 

For the next image, the left lens of a pair of  BenQ active glasses was placed a few centimetres in front of the camera. This had the effect of blocking out the right eye image almost completely:

1030143W2000RightViewExtinguishment.thumb.jpg.87bf78f21e9a81a308216de6873b12e9.jpg

 

 

The number visible just above the the word "lens" in the yellow text is not crosstalk, but due to the glasses left lens not being positioned quite low enough.

 

For this final image of the W2000, the right lens of the BenQ active glasses is able to extinguish the left image fully (well at least in this photograph; in real life I could see some of the numbers very, very faintly):

 

1030144W2000LeftIExtinguished.thumb.jpg.afa23a87805f3d50d37f0b8d31a6c8e1.jpg
 

In my opinion, the crosstalk result with my W2000 exceeds the performance needed for comfortable and clear 3D viewing of 3D Blu-rays. The other night we watched Hugo and the 3D image quality was a delight.

 

 

Other forum members might like to try the test image, or video, and see how their projector (or flat panel) performs.  Another thread where the video test file is referred to (and some results reported) is this thread on avsforum from 2010:  https://www.avsforum.com/forum/191-3d-displays/1291751-how-much-crosstalk-ghosting-has-your-3d-tv-test.html

 

For general interest, a well organised test of various 3D flat panels can be found at: http://www.displaymate.com/3D_TV_ShootOut_1.htm

 

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I'm a bit of a fan of movies in 3D having amassed around 120 titles over the years.

I have a several year old Sony TV that is 3D, it's 3D crosstalk performance could be pretty woeful in retrospect [It's no longer my main TV].

 

When considering my last purchase, I was leaning towards upgrading my none 3D Sony PJ and getting one of the upper rung JVC PJ's as they get good user reviews, and the 3D performance seems to be no slouch either.

This decision was mainly based on the fact that there were no longer any 3D capable TV's being sold, or so I thought at the time [NOV 2017]

The was a single Hisense model that was 4K and also 3D capable, but it was a massive 75", even then I thought I'd go check it out.....basically I canned that after a demo.

 

Then I got wind of the fact that Panasonics EX780a 4k model TV's were also 3D capable, but strangely no mention of this 3D capability could be found on their website at the time, the only way I found out was from reading a review at the UK based AVforums.

 

I went and checked out a 65" model and it seemed fine to me, so after a bit of haggling ended up get it for a very good price.

After letting the TV's electronics bed in for a bit, and me getting used to what the set looked like uncalibrated, I watch a few 3D movies, this is a active glasses real 3D TV by the way.

Anyway, it wasn't too shabby with 3D material, and that was without using the available 3D adjustments, once I tweaked those the picture left the Sony TV's 3D for dead.

 

But the biggest change was once I had calibrated this TV, it now performs like a very much more expensive TV, but it also made 3D look a lot better as well, which I was very surprised at, as none of the controls used to calibrate the TV have anything to do with 3D performance.

 

Where this TV's out of the box settings look fine to most, once you measure them, the Grey Scale and Gamma are WAY out [And that's even when in True Home Cinema mode, which is the closest to D65], I suspect this 'Tuning' is to make the TV seem brighter and cooler in a store where it competing against Samsungs ETC over bright and very blueish/cool looking screens.

 

Where these Grey Scale and Gamma parameters are out of whack, it would also seem part of the reason 3D crosstalk can seem worse, certainly more obvious at least.

It's basically giving a edge enhancement to the perceived crosstalk due to luminence errors, especially on high contrast 3D movies like Happy Feet [If ever there was a 3D torture disc, that's it]

 

Sure there are still some crosstalk problems, I think quite a few of them are down to how well 3D was implemented on the actual discs, I've got enough 3D discs to know that they can go from woeful to amazing.

 

I think watching 3D movies on a TV suffer certain problems and on a PJ different ones.

A TV is more likely to suffer crosstalk [or seem to] due to how close you are to the screen.

A PJ is going to have a dimmer picture, and possible crushed Blacks due to the PJ automatically opening up the Iris for the extra light output.

Despite the technical problems, I still enjoy watching 3D material, tis a pity they stop developing it.

 

Anyway I can't wait for the Jean-Michel Cousteau movie Wonders of the Sea, which is in 3D

 

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3 hours ago, Tweaky said:

Where these Grey Scale and Gamma parameters are out of whack, it would also seem part of the reason 3D crosstalk can seem worse, certainly more obvious at least.

It's basically giving a edge enhancement to the perceived crosstalk due to luminence errors, especially on high contrast 3D movies like Happy Feet [If ever there was a 3D torture disc, that's it]

Yes. Even if a TV has pretty reasonable grey scale performance in 2D mode, 3D mode will typically trigger the TV to operate at a higher brightness level (to overcome the 50% or more attenuation of brightness caused by the use of 3D glasses). And this may throw the gamma out and cause exaggerated contrast. (I recall having that issue years ago with a Panasonic plasma 3D TV.)

 

3 hours ago, Tweaky said:

Sure there are still some crosstalk problems, I think quite a few of them are down to how well 3D was implemented on the actual discs, I've got enough 3D discs to know that they can go from woeful to amazing.

The authoring of the 3D on a Blu-ray disc can be arranged to avoid high contrast between the Left and Right images. For example this is a feature of the video editor Sony Vegas Pro. 

A lot of the amateur 3D home videos uploaded onto the net don't use any softening as between the Left Right views and unless you have a display device with a very good native crosstalk ratio (or one that can actually soften the 3D disparities with on-the-fly processing), these amateur 3D videos can sometimes lead to very distracting crosstalk artefacts appearing.

 

A workaround is to turn down the brightness and/or contrast. I need to do that sometimes with my current flat panel 3D TV.

 

3 hours ago, Tweaky said:

Anyway I can't wait for the Jean-Michel Cousteau movie Wonders of the Sea, which is in 3D

Yes that certainly looks likely to be a "visual feast". I may well get a 3D Blu-ray of it when available. (I see that an Italian 3D Blu-ray version of it has been released, under the title Le Meraviglie Del Mare.)

 

I've greatly enjoyed 3D nature Blu-rays narrated by David Attenborough. I have commented on some of these in the past:

 

 

 

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I'd been watching out for those David Attenborough 3D titles to become available in Australia for ages, never saw them.

 

After doing a search I now see that there is a region free version of all three different 3D Documentaries he did as one pack.:)

Kingdom of Plants 3D, Galapagos 3D and Micro Monsters 3D.

 

https://www.amazon.com/dp/B00FEDUIAK/ref=sspa_dk_detail_0?psc=1&pd_rd_i=B00FEDUIAK&pd_rd_w=DY0YL&pf_rd_p=21517efd-b385-405b-a405-9a37af61b5b4&pd_rd_wg=bDVbG&pf_rd_r=ESD062Q3N7CKYAV8BH13&pd_rd_r=55640301-1c5b-11e9-b113-3f4681716abd&smid=ASWAXZ6NEI8CE

 

I'll place a order now.

🤔Shamefully I've just realized I have 5 3D titles I bought at the end of NOV that I still haven't watched.

Incredibles 2, Antman and the Wasp, Avengers Infinity wars,Jumanji welcome to the jungle and Transformers Uprising.

 

I also saw in a email from JB that they were having a clearance of 3D titles last weekend, hopefully they will continue to carry 3D titles, but they no long seem to have a separate section for them in the 3 JB stores I usually visit in Sydney city.

 

Edited by Tweaky

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