Anaglyph images/movies on a LCD TV

[chapas]

Hello guys.

I got a pair of red-cyan glasses to watch material prepared in anaglyph red-cyan.

Everything works fine on my computer monitors (CRT and LCD alike), but when I try to watch the material on my LCD TV, there's excessive ghosting.

Here's a image that shows what I mean:

http://en.wikipedia.org/wiki/File:Dusk_on_Desert.jpg

The biggest cactus to the right, when viewed only thru the red filter, shows a ghost to its left that differs depending on the device:

PC Monitor (LCD or CRT): the shadow is almost imperceptible.
42'' LCD TV: the shadow looks embossed, clear, and has all the cactus features well defined.

I read about Chroma Downsampling 4:2:0 causing most of these problems, and that most TVs do it, but I don't know if there's a fix for this.

I tried setting the Pixel Format in my ATI 6450 card to all the options, but the result is the same.

Can anyone shed some light on this? I'd be interested if you can successfully watch anaglyph images/movies in your 2D LCD TV.

Thanks.

[Asmodian]

From the limited understanding I have; if the blue image is darker with a red filter you might need to calibrate your TV. It probably displays cyan with less green or blue than it should or red isn't bright enough.

Even using something like color bars (http://en.wikipedia.org/wiki/SMPTE_color_bars) to do calibration should be enough.

edit: Also try normal or warm for white color or whatever they call it on your TV. ;)

[chapas]

Hello Asmodian.

My TV is not a known brand one, and I had to "calibrate" it more than I want to admit. I tried changing individual channel gains with the service menu to no avail, even changing the cool/normal/warm setting.

But then this issue first appeared on one of my friend's Sony LCD TV, so I started to worry it had to do something with LCD TVs in general.

Did you try watching anaglyph on your TV? In my case, I can only do it with PC monitors, no matter how badly calibrated they are.

Thanks for the tips.

[Asmodian]

Hello Asmodian.

My TV is not a known brand one, and I had to "calibrate" it more than I want to admit. I tried changing individual channel gains with the service menu to no avail, even changing the cool/normal/warm setting.

But then this issue first appeared on one of my friend's Sony LCD TV, so I started to worry it had to do something with LCD TVs in general.

Did you try watching anaglyph on your TV? In my case, I can only do it with PC monitors, no matter how badly calibrated they are.

Thanks for the tips.

Sorry I have a plasma TV and no red-cyan glasses.

Don't assume an expensive TV is calibrated correctly.

If you think it is really a monitor vs TV issue and not calibration then maybe your source material is encoded at PC levels not TV levels? Try a ColorYUV(levels="PC->TV") in Avisynth. My plasma doesn't handle PC range content well even when I send it full range RGB. Plasmas are pretty different from LCD TVs though.

There are no manufacturing differences between LCD monitors and TVs so I don't think it can be something fundamental.

Do you have a small sample of anaglyph red-cyan video I could examine?

[hello_hello]

Not that I've had experience with a wide range of TVs, but wouldn't they generally expect TV levels?

Asmodian is probably on the right track though. I can't test it either but I assume your video card isn't set to convert TV levels to PC levels which means the TV picture isn't correct. Do 2D images look okay on the TV? They're weren't unusually dark before you calibrated it or anything like that?

I have an Nvidia card but if memory serves me correctly ATI cards/drivers have a lot of image enhancing options enabled by default, possibly including converting TV levels to PC levels. Have you tried testing the 3D effect with all your video card's video enhancement/changing options completely disabled?

Edit: Another thought... does your TV have any of it's image enhancement features enabled? Dynamic contrast, that sort of thing?

[Asmodian]

I have ordered a pair of glasses, they are very cheap. :D

[chapas]

Asmodian: I'll appreciate your testing, and I'm sure you'll like the 3D effect!

hello_hello: I tried many things:
-Pixel format: it's an option of my ATI card's drivers. I switched between YCbCr 4:4:4, YCbCr 4:2:2, RGB 4:4:4 Studio (Limited RGB), RGB 4:4:4 Standard (Full RGB). RGB Limited was not supported by my TV, but the rest looked the same for 3D.
-Changed output in PotPlayer: http://www.softoxi.com/media/screenshots/000/005/potplayer_2.jpg Many options but not made a difference.

I'm using Stereoscopic Player's "3dtv.at Stereo Transformation" directshow filter for the anaglyph composite, but it's easier to test for proper 3D with a still image. If it works with the cactus image, it works with all 3D anaglyphs. I say it works fine if, instead of seeing the embossed ghost of the cactus, you only see a blurry shade and the expected 3D depth effect.

My TV has all the image enhancements options disabled, and the video card too.

[Asmodian]

The options we are talking about are:
YCbCr processing [Standard (Y: 16-235, CbCr: 16-240)]
ATI's YCbCr->RGB conv. [Comptuter monitor (RGB: 0-255)]

That looks correct for PC viewing on a TV. That said you also need to convert the video itself to those ranges. Try setting the YCbCr->RGB conv. to limited ranges, TV instead of Computer monitor.

[chapas]

Those settings are the default, and I tried changing them but nothing works so far. Waiting for your testing!

[hello_hello]

I was involved in a discussion regarding Potplayer and the levels used on playback in another forum a while ago. Your screenshot is of Potplayer's options, yes?
I think the colour space options in the screenshot only apply if the first one is on something other than auto, but anyway....

The poster in the other forum was using Potplayer and noticed the video displayed darker on his monitor when compared to MPC-HC (which relates to one of the reasons I asked if 2D video looks okay on your TV). Some renderers expand TV levels to PC levels automatically, and in the case of the OPs problem in the other forum, there seemed to be something unexpected when using Potplayer which gave a "double expansion" making the video look too dark on his PC monitor, while it didn't happen when using the same renderer and MPC-HC.

I can't remember if it was Potplayer or his ATI video card doing something odd, but in my case (using XP and a Nvidia card) I can't use a renderer such as EVR or Haali which automatically expands TV levels to PC levels as I have the PC hooked up to both a monitor and a TV and while they display video fine on the monitor the TV expects TV levels so the picture is too dark. Setting the video card to output TV levels seems to (if memory serves me correctly) make no difference. In my case I leave everything on TV levels except the output to the monitor, I set the video card to output PC levels to it and that works fine.

The upshot of it all is unless you're certain 2D video is displaying with the correct levels on your TV, try using a renderer with Potplayer which doesn't expand TV levels to PC. WMR9 doesn't. Alternatively, try comparing the same 2D video on your TV using MCP-HC and Potplayer (it'd be interesting to know if the renderer Potplayer is currently using displays video on your TV the same way it does when using MPC-HC). Once again, the EVR renderer should expand the levels when using MPC-HC (although I think there's a right click option to tell it not to) but the WMR9 renderer won't. The levels which your TV eventually receives may or may not also depend on your video card's settings.

[chapas]

hello_hello: The colors look normal, not too bright nor too dark. I will try using a different renderer to see if there's a difference. I'll report back with results. Thanks!

[chapas]

I tried all renderers. No change at all. I even tried the shaders in MPC-HC to no avail.

[hello_hello]

I guess if the colors look normal then they look normal.... maybe I'm completely on the wrong track. It's not so much the colors though it's more the contrast. If it's correct, black should look black, not dark grey (or vice versa). I watched video on my PC monitor for quite a while before discovering the levels were wrong. Anyway....

It does seem a little odd to me that all renderers look the same, but I really don't fully understand how renderers and video cards interact.
I can only test the Haali renderer as I use XP, but if I have the video card set to display video according to the video player's settings, (using MPC-HC) the WMR9 renderer produces a slightly "washed out" picture on my PC monitor, whereas the Haali renderer definitely expands the levels and it's darker.
Where I don't understand the process, is if I use the video card to expand the levels, the WMR9 renderer then looks fine, but the Haali renderer still looks the same (still fine). It's not like the levels get expanded twice. Therefore if I changed renderers on my PC and the levels remained the same I'd assume they were already being expanded to PC levels somewhere else in the chain. You did restart the player after switching renderers?

MPC-HC also has a right click option for changing levels. It's under Renderer Settings/Output levels. It's greyed out in my case so I guess it applies only to a particular renderer or maybe only works in later versions of Windows, but it appears to be set to PC levels by default so it may be worth checking.

As I said, maybe I'm completely off track. When you said the issue first appeared using your friends TV were you using your PC for playback or a different device? It's just that as you said a CRT or LCD monitor looks fine, not looking fine on an LCD TV does seem kind of odd unless the levels are wrong.
I guess after all that the simple question would be does video look the same on your TV if you use a different playback device to play it.... ie a DVD or Bluray player? If it does, then I guess it's not a levels issue.

[chapas]

Yes, I restarted the player for it to take the renderer change. My conclusion is monitors, no matter how badly calibrated, produce good anaglyph. There's probably some filter in my TV that I can't turn off that's messing with my picture. Hopefully someone can test in their LCD TV to get a better idea if the TV is the problem. Thanks hello_hello!

[Asmodian]

I actually have a somewhat different experience.

I notice less of a dual image in the red eye of anaglyph video on my TN monitor and plasma TV than my IPS monitor. On my main monitor this clip (http://www.youtube.com/watch?v=uKujOudUk0w) isn't really watchable while it looks pretty good on both my TV and my really cheap TN secondary monitor. The TN panel does have a LED backlight.

All my displays are calibrated but only my main monitor has a wide gamut. My wide gamut display has a pretty different green primary (red is a bit off too) so that is probably my issue. All the primaries are approximately correct on my TN panel and the green is just a little bit off on my plasma TV (compared to rec.709).

I can deal with wide gamut using MadVR and downloaded a clip (http://www.savevid.com/video/sky-diving-3d-anaglyph-video.html) to see if if that helps. It did! Using madVR to set the primaries it looks better on any display. It is totally different, almost perfect, on my main display (this one looks the best of all three with madVR).

Most LCD TVs are IPS panels but wide gamut is not standard, not really uncommon though. Primaries do not change much by changing settings (edit: unless you have a gamut setting), the only way to fix the gamut I know of is MadVR.

Just to note, all calibrations and primary measurements done with a Spyder 3.

plasma TV:
Red Yxy 36.17 0.638874 0.332644
Green Yxy 84.801 0.26754 0.630317
Blue Yxy 12.991 0.153116 0.06145
White Yxy 42.964 0.312161 0.329939

Wide Gamut IPS Monitor:
red Yxy 46.848 0.668016 0.314039
green Yxy 98.842 0.159967 0.698481
blue Yxy 10.927 0.147222 0.058411
white Yxy 154.528 0.31338 0.329167

[chapas]

Great findings, Asmodian!

I will try to use madVR. Is there a specific setting to correct the colors, or just using it will suffice?

Thanks.

[Asmodian]

Well you need to know what your primaries are, I measure mine using a colorimeter.

Just using it won't change anything. :(

[smok3]

for testing, a single HD frame i did the other day:
http://shrani.si/f/1Y/Rf/xwy2Ymc/bansihdriandanaglyph4sig.png

(the dot on the nose does look wrong, i know)