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Discussion Starter · #1 ·
Greetings! I'm using my computer as my movie player through HDMI to a Toshiba LCD TV. What order or strategy should I use to properly calibrate the TV?


To ellaborate: Should I do all the calibrating using the PC's settings (eg.: Brightness, contrast etc.) and leave the TV's settings alone? And if I did this, should I adjust the TV's settings to their max or lowest? Or would I do the opposite and do all the calibrating through the TV a leave the PC alone?


One thing I know for sure is that there are brightness levels that the TV can't adjust. It seems to just brighten the signal rather than adjust the source. Hope that makes sense. For example, I can brighten the PC and then see things on the TV that weren't visible. But If brightened the TV and not the PC, I wouldn't see those things.


Appreciate all your help here. Thanks in advance!
 

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Hi, I am interested to hear the answer from one of the more experience folks but I would think you should use a different source for patterns input that will output the signal with no processing and calibrate the TV.

Then plug in the PC and recalibrate using the PC settings.
 

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Discussion Starter · #3 ·
Thanks airscapes! It's certainly worth trying your suggestion. I'd like to see how it looks. Then if later someone else responds, it's not a problem to try that suggestion out.
 

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A big part of this is setting up the graphics card settings on the PC.


I've got an ATI card in my HTPC. I have it setup for YCrCB 4:4:4. That contracts the desktop color space from 0-255 to 16-235 so that Desktop content runs at video levels. I then go into the video settings and force video content to 0-255, that means that DVD, BD, and other sources that use hardware video acceleration are expanded to run at desktop levels in the OS, but remember that desktop levels are being output at video levels.


So then when you calibrate you use PC levels when you calibrate. The downside to all of this is that you can't get BTB or WTW.


Calibrating from a PC is a tricky thing, and you really need to understand what's going on under the hood and it really helps to have a reference source to compare to (DVD player, BD player with a calibration source).
 

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Quote:
Originally Posted by adabo /forum/post/20880675


I can brighten the PC and then see things on the TV that weren't visible. But If brightened the TV and not the PC, I wouldn't see those things.

Like sotti mentioned many computers will allow you to alter their output, so often you can choose if you want to send video levels (16-235) or computer levels (0-255) to the display. You may also need to set the display to match with the output of the computer. Many computers default to outputting computer levels (0-255), so if you don't change the output like sotti was talking about, you may need to set the TV to expect computer levels. Different TV manufacturers use different terms for their controls. I think Sony uses 'limited' for a video level RGB range (16-235), and 'full' for computer RGB levels (0-255). Samsung I believe has an HDMI setting for changing the RGB range. My main point is that the quote makes it sound like the TV may not be set correctly for the current output from the computer. While you may wish to alter how the computer outputs, generally I would suggest to leave most of the computer settings at their defaults and make as many setting changes as possible at the display.
 

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Discussion Starter · #6 ·
sotti, alluringreality: Thanks for the detailed responses. Unfortunately, I'm a novice tweaker and don't understand the terminology you use nor do I know what the numbers you gave mean. I'm going to do my best to see if I can find those values in one of these menus, but I don't recall seeing it.
 

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Quote:
Originally Posted by adabo /forum/post/20882466


sotti, alluringreality: Thanks for the detailed responses. Unfortunately, I'm a novice tweaker and don't understand the terminology you use nor do I know what the numbers you gave mean. I'm going to do my best to see if I can find those values in one of these menus, but I don't recall seeing it.

For the novice, my advice would be simply don't do it. It's too complex and tricky to get right.


Try to find a primer on the differences between PC levels and video levels.


Are you familiar with bit depth? PCs and Video are both 8bit (per channel) sources 8bits give you 256 step or 0-255. PCs have black at 0 and white at 255. Video sources have black at 16 and white at 235. Because of that making a PC work with at TV, or a PC monitor work with a cable box can be very tricky. Both the PC and the TV may try to auto-negotiate levels and frequently get it wrong. Understanding what your particular display and PC are doing are of the utmost importance if you want to get it right.
 

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The upsilon mixer may be the simplest solution for you , google it or search for it on here.
 

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The key things to look for are.


Do I want to send video or PC levels to the display.


If I send PC levels do I want to setup my display for video levels or have the PC setup the video levels for a PC level environment.


I usually start by ensuring my display is not clipping or crushing ( as much as its capable) 1-254. Then I hardware calibrate the display. Then I have the upsilon mixer profile the display chain and correct it for whatever target I'm after ( usually rec.709 , 2.35 gamma , and a range of 16-240).


The reason for doing it primarily on the PC rather than the display is that graphics cards ususally have a lot more colour precision than the display hardware.


Things like whether your display functions best with hdmi or dvi (or even vga...don't discount that as it sometimes offers the cleanest image) and whether the chroma upsampling is better handled at the card or the display side. (you may have to compromise here depending on display foibles).


Whether you require and accurate desktop as well as accurate video . What sort of video surface the chosen playback app is using is also relevevant to how its corrected.
 

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Quote:
Originally Posted by sotti /forum/post/20881297


I've got an ATI card in my HTPC. I have it setup for YCrCB 4:4:4. That contracts the desktop color space from 0-255 to 16-235 so that Desktop content runs at video levels. I then go into the video settings and force video content to 0-255, that means that DVD, BD, and other sources that use hardware video acceleration are expanded to run at desktop levels in the OS, but remember that desktop levels are being output at video levels.

I've always found this gives a nasty looking greyscale, as 1st conversion from video YCrCb -> display space RGB is rounded to 8 bits. For the smoothest looking video I've found you need to avoid the expansion/contraction.


Also not sure how your own settings sit with the advice you give in other threads to always calibrate for full range of WTW.


Jon
 

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Quote:
Originally Posted by JohnAd
I've always found this gives a nasty looking greyscale, as 1st conversion from video YCrCb -> display space RGB is rounded to 8 bits. For the smoothest looking video I've found you need to avoid the expansion/contraction.


Also not sure how your own settings sit with the advice you give in other threads to always calibrate for full range of WTW.


Jon
Mostly it's just the PC is so flawed as a source you simply have to make compromises.


How can I show WTW and have desktop black match video black? The HTPC has about three axis of performance for video quality. Ease of use, utility as general purpose machine, and outright video quality. Especially if the HTPC is only one of the components in your AV rack.


So if my choice is crush all the black for internet video and for the desktop and for games on the PC or clip WTW, clipping WTW is the less offensive choice. Also clipping in the source, is much different than clipping in the display, clipping the source is a clean precise thing, clipping at the display may or may not clip in an even fashion per channel and can also cause discoloration.
 

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Quote:
Originally Posted by alluringreality
Different TV manufacturers use different terms for their controls. I think Sony uses 'limited' for a video level RGB range (16-235), and 'full' for computer RGB levels (0-255). Samsung I believe has an HDMI setting for changing the RGB range.
I was digging around the settings on my Panasonic BDT-210 BD player last night and looked at the HDMI Settings. It has a YCrCb setting for 4:4:4 and 4:2:2 as well as a Standard RGB and Enhanced RGB. I set the YCrCb to 4:2:2. Would it be safe to assume that the Sony designation of "limited" and "full" would be comparable to the 210s Standard RGB and Enhanced RGB (16-235 and 0-255 respectively)? I don't use HTPC, just run the BD thru the AVR and out to the tv but it's nice to learn as much as possible about all of this. I did calibrate my set using the 210 and the AVS HD709 disk.
 

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Quote:
Originally Posted by Otto Pylot
Would it be safe to assume that the Sony designation of "limited" and "full" would be comparable to the 210s Standard RGB and Enhanced RGB (16-235 and 0-255 respectively)?
That seems reasonable. With computer-levels (0-255) the general expectation is that you will lose the 1-15 and 236-254 video information, as 16 is expanded to 0 and 235 goes to 255. Expanding 16-235 video to 0-255 levels also introduces grayscale banding, because some of the gray single step-changes end up as two-step changes. Generally for critical viewing the recommendation is to pass the entire video range to the TV without modification, but this may not be very practical with computers, and modifying the signal might allow for adjustments not offered in the display (color correction, gamma, etc.).
 

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Quote:
Originally Posted by alluringreality /forum/post/20890733


That seems reasonable. With computer-levels (0-255) the general expectation is that you will lose the 1-15 and 236-254 video information, as 16 is expanded to 0 and 235 goes to 255. Expanding 16-235 video to 0-255 levels also introduces grayscale banding, because some of the gray single step-changes end up as two-step changes. Generally for critical viewing the recommendation is to pass the entire video range to the TV without modification, but this may not be very practical with computers, and modifying the signal might allow for adjustments not offered in the display (color correction, gamma, etc.).

Thanks. It's starting to make sense. It seems to be more work for those who use HTPC than for those of us who don't but it's still good to know the differences and why. The education never stops
 

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Quote:
Originally Posted by sotti /forum/post/20889367


How can I show WTW and have desktop black match video black? The HTPC has about three axis of performance for video quality. Ease of use, utility as general purpose machine, and outright video quality. Especially if the HTPC is only one of the components in your AV rack.

Set desktop to 0-255 set video conversion to 16-235, create a gamma ramp that maps desktop black to 16 and desktop white to 235 for use with non-video.


Not a simple solution but a high quality one.


John
 

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Quote:
Originally Posted by sotti /forum/post/20889367


So if my choice is crush all the black for internet video and for the desktop and for games on the PC or clip WTW, clipping WTW is the less offensive choice. Also clipping in the source, is much different than clipping in the display, clipping the source is a clean precise thing, clipping at the display may or may not clip in an even fashion per channel and can also cause discoloration.

Agree that each set-up is a set of compromises, my comment was that's not how it comes across sometimes.


John
 

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hi,


assuming htpc is used for video playing only, and that is possibile to set card video output to "video levels", isn't enough quality signal to give to television as every source (dvd, bd) should do?


then use video material for hardware calibration, and finally profiling software for fine tuning... even if I'm not sure for this final step as I don't know how software output light that probe should measure is intended to be...


any comment is welcome, I would to understand if possible.

thank you.
 

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Quote:
Originally Posted by 8rnity /forum/post/20920645


hi,


assuming htpc is used for video playing only, and that is possibile to set card video output to "video levels", isn't enough quality signal to give to television as every source (dvd, bd) should do?


then use video material for hardware calibration, and finally profiling software for fine tuning... even if I'm not sure for this final step as I don't know how software output light that probe should measure is intended to be...


any comment is welcome, I would to understand if possible.

thank you.

If I'm profiling I usually maximise the dynamic range and precision on the display. Basically set brightness for 16 and contrast so that the white point is as high as it will go without clipping in hardware terms and rely on the profiling to handle grayscale and white point mapping and gamut.


You may also benefit from setting brightness to show everything up from 1 and let the profiling handle the clip to 16 although meters tend to be less accurate than eyeball down there.
 

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ok, I prefer not to maximize dynamic but prefer take greyscale so 100% IRE is at preferred level, usually 30ftl.


but what about video levels? is it correct that once graphic card is set to have 4:2:2 and 16-235 out, tv should be already set to accept this signal without problems?
 
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