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Author Topic: Need some tips on how to set brightness correctly  (Read 20205 times)

InflatableMouse

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Need some tips on how to set brightness correctly
« on: June 30, 2012, 03:20:44 pm »

With my new HTPC installed I figured it was time to redo how everythings hooked up. I managed to free up a HDMI on the Denon for the htpc. Previously, the htpc was hooked up to HDMI2 on the TV and sound ran over optical. As each HDMI input on the TV remembers its own display settings I never had the problem that different sources coming from the Denon differed in brightness but I do have that issue now.

Oke, so with the new htpc on the Denon I find that movies are too dark. The difference is not huge, maybe 6-8%. When I make that look right on the TV controls, broadcasts are too bright. I tried increasing brightness from the Intel HD graphics control panel, but somehow it looks goofed. It's like some dark shades look dirty or even clipped. Either way it didn't look right. I tried comparing it to increasing the brightness on the TV, but the time between resetting the Intel control panel and setting the brightness on the TV is so long I can't remember for sure what it looked like. I can't compare it with a flip of a switch. Obviously the difference isn't huge but I still believe the controls from the TV work better than the Intel control panel.

I'd like to hear how you folks fix that, as I can't believe I'm the only one having this issue.
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Scolex

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Re: Need some tips on how to set brightness correctly
« Reply #1 on: June 30, 2012, 03:49:42 pm »

Have you gone through the Windows Calibrate Display routine? If no type calibrate in the start menu search and select Calibrate Display Color.
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Sean

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Re: Need some tips on how to set brightness correctly
« Reply #2 on: June 30, 2012, 04:21:58 pm »

Are you using RO HQ? If so, RO HQ uses Madvr which lets you set black levels at either 16-235 or 0-255. Maybe your TV broadcasts are displayed with the EVR renderer using (16-235) and your Movies are using MadVR's renderer (0-255). If so, you can try to set MadVR to 16-235 and all your videos should match.

See this article on blacl levels if your unfamilar with it: http://www.audioholics.com/tweaks/calibrate-your-system/hdmi-black-levels-xvycc-rgb
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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #3 on: July 02, 2012, 04:12:20 am »

Thanks.

First I made sure all was set to wide color range (Denon was still set to limited) and TV settop can't be set so I asume its limited.

Next I've reset the TV to factory defaults and redid the calibration on that too and then I did the windows calibration (gamma was slightly off, the rest was good). Broadcasts still look like it has a bit more contrast yet it has less detail in black. It's not much though so I'm good with it.

I've decided the HTPC is more important, we don't watch televion that much.
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Jong

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Re: Need some tips on how to set brightness correctly
« Reply #4 on: July 02, 2012, 11:14:51 am »

IM, don't want to make more work for you if you are happy, but correctly setup there should be absolutely no difference between TV and your PC and, out of the box, if they are different it is almost certainly the PC that is wrong. Depending on your GPU and settings you need to look at the 'pixel format' and 'dynamic range' your PC is using as well the MadVR settings described previously, if using Rec October HQ. I would suggest downloading the .mp4 version of the AVS HD709 test suite and use the 'basic settings' test patterns until things are just right. You want to calibrate for 16-235 limited range for compatibility with other video sources.
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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #5 on: July 03, 2012, 12:46:42 am »

I don't nessecarily want compatibility with other sources, I want the tv broadcasts to look as good as it can without sacrificing the htpc experience. All we watch is the news and a few other programs - nothing entertaining ;).

So, correct me if I'm wrong, but if everything (htpc, receiver, TV) supports wide range shouldn't I be using that for the best possible experience? When I switch back and forth between 0-255 to 16-235 I find that 0-255 looks warmer and more vivid or alive.
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Jong

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Re: Need some tips on how to set brightness correctly
« Reply #6 on: July 03, 2012, 01:52:27 am »

Honestly, once you have recalibrated for "video levels" (16-235) there will be absolutely no difference in warmth or brightness. You are only seeing a difference because you are not recalibrating when you switch.

Just about all commercial video material inc bluray is stored using video levels. The issue is if you expand this to 0-255 you risk introducing "banding" - unwanted artefacts due to the interpolation of 0-255 from the original 16-235. Compare a "ramp" test pattern with your TV calibrated for video levels and for full range to see if you can spot the difference. The effect is not normally huge (madVR is especially good at it) and you may not care, but if you calibrated your TV for full range, along with the incorrect display of material from other sources, all the downside is on the side of using full-range. In the end though it's up to you. If using full range is easier and you don't mind the disadvantages do it! But there are no quality advantages!
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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #7 on: July 03, 2012, 01:58:14 am »

Cool.

I'll set it all back to limited and redo the process. I just assumed wide was better than limited. When I read 'limited', I think 'no' automatically  ;D.
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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #8 on: July 03, 2012, 11:43:07 am »

Oke I still can't get it right, it looks like the moment I start a movie brightness goes up about 20 clicks. Here's what I've done so far:

1. set receiver output to RGB normal (16-235)
2. Set the TV to limited (meaning 16-235)
3. Recalibrate the TV (hardware reset and redo the display wizard). When its done I disable power savings and dynamic contrast, I disable edge enhancement and set sharpness down to 25.
3. Set MadVR to 16-235
4. Set the display settings under Color Enhancement to Disable YCbCr and under Monitor/TV set Quantization Range to Limited and disable IT Content (tooltip says to disable to let driver control quality, enable to let monitor do its thing).

At this point the desktop looks good and even TV broadcasts are actually good too.

When I start a movie with MC, the display goes blank, blinks and the screen comes back too bright. The driver control panel then says "wait for settings to update" and on the Monitor/TV settings Quantization Range is back to Default and IT Content is checked again. When display mode is not fullscreen I can see from the desktop/startmenu that its way too bright, about 20 clicks on the TV brightness controls.

When I stop playback, the screen goes blank again and reinitializes to come back to its original (darker) setting.

Appreciate any help with this.

Thanks.
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Jong

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Re: Need some tips on how to set brightness correctly
« Reply #9 on: July 03, 2012, 11:58:51 am »

It can be tough gettings things consistent and I'm sorry if I'm pushing this on you. Looks like you have an Intel GPU. You might need to seek out a forum of users or look on AVS Forums for help. I always use AMD GPUs, largely because I know how to get them consistent for all media! Also, when you say "movie" what do you mean? DVDs don't use MadVR.
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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #10 on: July 03, 2012, 12:18:16 pm »

Don't feel bad  :-*

I actually like fiddling around  8)

A movie in my case would be an MKV with 1080p x.264 + DTS(-MA sometimes) streams.

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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #11 on: July 03, 2012, 12:22:56 pm »

Should I enable YCbCr when the option is available?

My Denon has that on its hdmi output and the IGP driver also has that option. I've tried reading about it on wikipedia but I had to stop to prevent my brain from exploding.
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Jong

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Re: Need some tips on how to set brightness correctly
« Reply #12 on: July 03, 2012, 12:28:24 pm »

Personally I use it, because it is the easiest way to get consistent levels for all media with AMD and I believe my TV prefers it. It is what It would normally expect from a STB or Bluray player. On the other hand MadVR outputs RGB, so that has to be converted back by the GPU. But the algorithms are well understood and essentially lossless and don't seem to have an impact on performance, so I am very happy to let the GPU do it.
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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #13 on: July 03, 2012, 12:55:48 pm »

Right, oke. I actually grabbed my Denon manual to see what it said about it and theres a warning that RGB range is disabled when I enable YCbCr on hdmi out. I assume that means when I enable it, its full range (0-255), is that correct?

And if that's so, shouldn't I enable that option in the driver control panel too for best results?

I'll try it out now see what it does.

Thanks.

PS. did make a post on avsforums too, lets see what comes from that.
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Jong

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Re: Need some tips on how to set brightness correctly
« Reply #14 on: July 03, 2012, 01:42:31 pm »

No YCbCr will be @video levels, always. Its mandatory. In fact Arguably HDMI only really had full range RGB at all becuase it has to be compatible with DVI, which was originally a computer monitor standard. Of course it is still possible for video to be over expanded (too dark, clipped at low levels) or over compressed (too bright, blacks are grey), so of itself it does not guarantee much.

Even now, what I do on every driver change is run through a battery of low luminance test patterns for true bluray, mkv, true DVD, regular SD AND desktop images to make sure they haven't broken anything and all is consistent! It's a pain but certainly it used to be essential. Not had a problem in a while though with AMD.

Bottom line, The only way to know if it right is to test it. You cannot make assumptions with this stuff unfortunately.
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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #15 on: July 03, 2012, 02:06:25 pm »

I just now finished testing with YCrBr. Enabled it on the Denon (left RGB normal alone) and enabled it on the driver.

When I entered the Denon menu, I noticed it was very washed, way too bright. After setting it to YCrBr, the screen went dark and came back less bright. That looked hopeful.

In Windows I set the option in the driver and xbmc is now playing videos on normal brightness levels. MC however was still too bright, not not nearly as much as it used to be. When I set MadVR to 0-255 it was good, matching xbmc levels. Whats weird is that the denon and the tv settings are set to normal in that respect. I can't control the setting in xbmc so I have no idea whats it set to there.

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Jong

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Re: Need some tips on how to set brightness correctly
« Reply #16 on: July 03, 2012, 02:23:50 pm »

Yeah, as I said it is never a good idea to just to assume what is right. It sounds like Intel works in a similar way to AMD on this and it is probably the thing that makes it more dependable. All apps and Windows can assume they have a regular full range video monitor and the GPU converts it to the right video levels for YCbCr. So, it is not surprising that full range is the right setting to use in MadVR in this circumstance.
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Jong

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Re: Need some tips on how to set brightness correctly
« Reply #17 on: July 03, 2012, 03:30:30 pm »

Oh, for completeness, I should have added that in YCbCr mode commercial players, which use an overlay surface for bluray, bypass all conversion and send YCBCr straight from disc to display, at least on AMD.
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InflatableMouse

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Re: Need some tips on how to set brightness correctly
« Reply #18 on: July 03, 2012, 03:57:06 pm »

Thanks for the help Jong.
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