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Contradictory calibration results - THX and AVS HD 709

post #1 of 10
9/2/09 at 9:03pm
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By 'calibrated' I mean brightness and contrast. That's all I'm interested in getting right at the moment. But I just don't get it. I've calibrated my Viera TH-L37G10A using the THX video calibration found on The Bourne Conspiracy PS3 demo game so that the drop shadow can't be seen on the THX logo (ie, it blends in with the background - this is supposedly 'correct') but then when I fire up AVS HD 709 (AVCHD) I have 'incorrect' brightness results.

The test I'm referring to in AVS HD is the second test under the "Misc. Patterns" main menu option. This test has two horizontal bars of vertically aligned brightness bars, one increasing in brightness, the other decreasing with one on top of the other.

At the same settings on my HDTV that are 'correct' in the THX, the results in this AVS HD test are incorrect. Black 16 and the bar that is next to it that is supposed to be brighter are the same black level. In other words, all four initial black bars are the same black level.

Now to describe my setup. My PS3 is set to limited RGB output. Superwhite is ON. DVD/BD is set to output at Y Cb Cr and I am connected to my HDTV with HDMI.

From my research I've gathered that the PS3 main menu (XMB) and games use RGB and that DVD/BD can output in either RGB or Y Cb Cr, depending on what setting is selected in the Video options of the PS3. As I've stated, in my case this is set to Y Cb Cr. So going by this information, the game and AVS HD 709 disc should both using the same base black of black 16.

So does anyone know why my results are contradictory and which test I should be using as the 'correct' one?
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post #2 of 10
9/3/09 at 9:52am
probably the 2 discs have different APLs
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post #3 of 10
9/3/09 at 10:33am
If you are attempting to setup the black level (with the brightness control on your display), you should be using the pluge pattern located in the "Basic Settings" menu of the 709 disc (its actually the first pattern in that chapter).
Quote:
Originally Posted by kidicarus7 View Post

By 'calibrated' I mean brightness and contrast. That's all I'm interested in getting right at the moment. But I just don't get it. I've calibrated my Viera TH-L37G10A using the THX video calibration found on The Bourne Conspiracy PS3 demo game so that the drop shadow can't be seen on the THX logo (ie, it blends in with the background - this is supposedly 'correct') but then when I fire up AVS HD 709 (AVCHD) I have 'incorrect' brightness results.

The test I'm referring to in AVS HD is the second test under the "Misc. Patterns" main menu option. This test has two horizontal bars of vertically aligned brightness bars, one increasing in brightness, the other decreasing with one on top of the other.

At the same settings on my HDTV that are 'correct' in the THX, the results in this AVS HD test are incorrect. Black 16 and the bar that is next to it that is supposed to be brighter are the same black level. In other words, all four initial black bars are the same black level.

Now to describe my setup. My PS3 is set to limited RGB output. Superwhite is ON. DVD/BD is set to output at Y Cb Cr and I am connected to my HDTV with HDMI.

From my research I've gathered that the PS3 main menu (XMB) and games use RGB and that DVD/BD can output in either RGB or Y Cb Cr, depending on what setting is selected in the Video options of the PS3. As I've stated, in my case this is set to Y Cb Cr. So going by this information, the game and AVS HD 709 disc should both using the same base black of black 16.

So does anyone know why my results are contradictory and which test I should be using as the 'correct' one?
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post #4 of 10
9/3/09 at 10:43am
Use the AVS disc, calibration in games is usually wrong because the consoles don't output BTB/WTW over RGB. Output RGB limited with the AVS disc to keep it a match to games.
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post #5 of 10
9/3/09 at 11:20am
If you can't tell 5% apart from black, then most likely brightness is too low. An LCD could be affected by average picture level, but from what I've seen from digital displays I wouldn't necessarily expect 5% to blend with black regardless of APL. If the PS3 works as documented, then you can simply use a video pattern to set display controls and it should also work for games.

One way to set brightness in a game without a pattern is to turn up brightness too high so that the black level is raised. To start you want the darkest items in the game too bright so that they are clearly lighter. Then begin turning down brightness and watch for a loss of detail. If objects or gradations completely disappear then you have gone too low. You basically want to turn down brightness until the darkest items become no darker if you were to go low lower with brightness. There is no below-black information expected in games, so all detail in the game should display. If you turn brightness too low so that objects completely blend into black then brightness is probably too low. I've done this sort of procedure on my Xbox, and then I've compared the brightness setting against what I got from using a video pattern. Either procedure resulted in almost identical settings, so the Xbox seems to output black for video and games at the same level as expected, and for that system I'd say to just use a video pattern to set brightness as commented above.
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post #6 of 10
11/26/12 at 5:46am
Hiya guys.

Are you saying that if video games on consoles don't output BTB/WTW, you should calibrate the so the next one up to below black is barely visible? If you understand that.

I'm guessing PCs output BTB/WTW.
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post #7 of 10
11/26/12 at 2:36pm
You may be getting 2 completely different things when you use a Game and a test/setup disc designed to get you to the right settings for movies. Games tent to be RGB 0-255 while movies are encoded in YCbCr 4:2:0 (and are usually best output from the disc player as YCbCr 4:2:2). If you setup with the game disc, then switch to a movie, you're likely to have blacks and shadows that are much too bright (black never gets black, just dark gray).

If you calibrate with the test/setup disc first, then play a game, you're likely to lose most of the shadow detail. The best solution for this is for your TV to have separate memories for each input so you can set the input used for gaming to RGB 0-255 so your setting for black will be correct for games. And so you can save a completely different Brightness setting for your movie input from the disc player.

Anothe fix is to set the game console to output RGB 16-235 or YCbCr 4:2:2 so that your games and movies will share the same black level. Some people have a serious aversion to doing that because they think they will lose something visible from the games, but it's doubtful the difference would be visible.

You could also set the disc player to output YCbCr at 0-255 (if the player has that option) or RGB 0-255 (again, if the player has that option) so that both movies and games would have the same black level.
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post #8 of 10
11/26/12 at 4:27pm
I thought Video games used the REC 709/sRGB space. Well the artists anyway. Which is what movies use, including the calibration discs. Or is it the YCBCR 4:2:0 in the way of doing it that way?
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post #9 of 10
11/26/12 at 5:33pm
Quote:
Originally Posted by Tyrone Burton View Post

I thought Video games used the REC 709/sRGB space. Well the artists anyway. Which is what movies use, including the calibration discs. Or is it the YCBCR 4:2:0 in the way of doing it that way?

YCC 4:2:0 is a way of encoding RGB data. It's effectively a compression scheme and is how DVD and Blu-ray store their content. HDMI uses YCC 4:2:2 or 4:4:4 for transmission.

YCC, like RGB is a relative colorspace. You have no idea how Red 255,0,0 is until you say that it's for sRGB, then you know it's x,y 0.64,0.33. The same goes for YCC, it's just a different way to pack the relative colormetric data that makes it take up less space for transmission.

If you want a good primer on the conversion read this http://www.dvd-replica.com/DVD/color.php


I think Doug missed in the original post that the console is setup correctly for optimum output, so this difference is either an issue with a dynamic contrast setting or is being caused by a bad encode on the THX optimizer. The THX optimizers are notorious for having the wrong levels.
Edited by sotti - 11/26/12 at 5:38pm
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post #10 of 10
11/27/12 at 4:18am
Yep. The only THX Optimiser I have found that matches results you'd find on a proper calibration disc is on the Star Wars DVDs. The Terminator 2 BD had a bad Optimser, came up on my TV very dark.

Some people say that the reason some if them are wrong is because their either movie specific or game specific. Seems like it's just badly made optimisers then.

Oh THX. Your confusing people ya know smile.gif
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