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For those struggling with brightness, contrast & backlight settings on LCD's

post #1 of 126
Thread Starter 
*This may be nothing new to a majority of the people here, but maybe it will help answer questions for some.*

Finally after piecemealing several threads together, I have come up with a method that works for me and maybe will help others newbies that are trying to figure out the relationship of brightness, contrast, and the back-light setting on LCD displays.

My equipment consisted of the AVS HD disc, an i1D2 and Chromapure.

Step 1: Brightness / black level
Use the black clipping pattern on the AVS HD disc. Crank your back-light up as high as it will go. It makes the flashing bars easier to see. Adjust the brightness until only 17 & up flash. Brightness is set for now.

Step 2: Contrast / White level
The 3 rules for setting contrast
1-No clipping
Use the white clipping pattern to see if your display clips at 235. Chances are it won't and you can 235 and above.
2-No discoloration
Here you need to use HCFR, ChromaPure, or CalMAN and your colorimeter. I am using ChromaPure and an i1D2.
Set your back-light to zero and put up either a 100% window or field. I checked both and had the same result. Set your contrast to about 75% and start raising it one step at a time. What you are looking for is when color is not being added anymore. You will most likely run out of red first. My red output peaked at a setting of 89/100. One step higher and red output dropped 3%. That is now the max your contrast can be without discoloration.
3-No eye fatigue
With my contrast now set and a back-light of zero, I was only outputting 17 ftL. I had to raise it to a setting of 3 to get 35 ftL. A setting of 4 gave me 43 ftL, and so on. In my normal viewing environment, either setting worked for me. I set mine at 3 for typical viewing. Make sure step 2 is still valid and your contrast and back-light are now set.

For a back-light check, go to the APL clipping pattern and make sure you can see 19-21 & up flash. If you can see below that, chances are your back-light may be too high.

This is the first time that I bothered checking all 3 rules on contrast and I have ended up with my best starting point heading to gray scale calibration. I didn't realize before how key step 2 is and the difference it makes.
post #2 of 126
...
Quote:
Originally Posted by duke32 View Post

Set your back-light to zero and put up either a 100% window or field. I checked both and had the same result. Set your contrast to about 75% and start raising it one step at a time. What you are looking for is when color is not being added anymore. You will most likely run out of red first. My red output peaked at a setting of 89/100. One step higher and red output dropped 3%. That is now the max your contrast can be without discoloration.

Out of curiosity, which ChromPure module were you using to measure color output?


For a back-light check, go to the APL clipping pattern and make sure you can see 19-21 & up flash. If you can see below that, chances are your back-light may be too high.

You're clipping 17 & 18. Black level is incorrect at this point.

post #3 of 126
Thread Starter 
I used the white balance module to measure color output. I guess you could use Raw, but I went with what was more visual.

How can Black level be incorrect? It was set and confirmed with the Black clipping pattern. If you're now going to raise the brightness based on the APL pattern, are you not going to start crushing Black? The method I used came from alluringreality's post here.
http://www.avsforum.com/avs-vb/showt...2#post20066562

Quote:


On the TVs I've looked at, a backlight or iris setting usually does not affect where a digital display clips. I use the first Black Clipping pattern to adjust the brightness control to the lowest setting where everything below 17 clips. In doing this it may be easier to spot the flashing in the pattern by setting the backlight high, and it may be more difficult to notice the flashing if the backlight is set low. Usually the backlight will not actually affect where the TV clips, so I consider it acceptable if you want to use a high backlight or walk up to the display to make the flashing easier to see.

Once you find the lowest brightness setting the TV is capable of using I would suggest moving on. Leave the TV at that brightness setting, go to the second APL Clipping pattern, set backlight to minimum, use typical room lighting, and view the TV from a location where you might usually watch. The white in the image and room lighting will probably make the flashing near black difficult to notice on most decent TVs. Start turning up the backlight control, and at some point you will likely be able to see 19 flash from your usual viewing location without touching the brightness control. Anyway, my point here is that clipping (brightness control) and light output (backlight control) usually are two different functions that don't necessarily interact. Room lighting can make near-black levels difficult to notice, and generally I would suggest turning up the backlight before increasing the brightness control.
post #4 of 126
Quote:
Originally Posted by duke32 View Post

I used the white balance module to measure color output. I guess you could use Raw, but I went with what was more visual.

How can Black level be incorrect? It was set and confirmed with the Black clipping pattern. If you're now going to raise the brightness based on the APL pattern, are you not going to start crushing Black? The method I used came from alluringreality's post here.
http://www.avsforum.com/avs-vb/showt...2#post20066562

There is only one correct black level setting using that pattern - clip 16, see 17.
post #5 of 126
While I own a plasma, a lot of things you said are valid here. Interesting read. I'm getting my meter soon and now the wait is getting worse haha.
post #6 of 126
Quote:
Originally Posted by buzzard767 View Post

There is only one correct black level setting using that pattern - clip 16, see 17.

I think the confusion here is about the clipping patterns. For the black clipping pattern (very low APL), you must see 17 and above. For the APL clipping pattern (medium/average APL), you must see at least 19 and above. The reason for this is that the white portions of the APL clipping pattern can make the black portions harder to see, making it harder to see 17-18 on some displays (but not all). These guidelines are from the pattern manual for the AVS disc.
post #7 of 126
Quote:
Originally Posted by PlasmaPZ80U View Post

I think the confusion here is about the clipping patterns. For the black clipping pattern (very low APL), you must see 17 and above. For the APL clipping pattern (medium/average APL), you must see at least 19 and above. The reason for this is that the white portions of the APL clipping pattern can make the black portions harder to see, making it harder to see 17-18 on some displays (but not all). These guidelines are from the pattern manual for the AVS disc.

Agreed. However, once contrast is set a return trip to the black clipping pattern must be made to ensure nothing has changed. If it has, readjust.
post #8 of 126
Quote:
Originally Posted by buzzard767 View Post

Agreed. However, once contrast is set a return trip to the black clipping pattern must be made to ensure nothing has changed. If it has, readjust.

Yes, everything can affect everything.
post #9 of 126
Quote:
Originally Posted by duke32 View Post

Step 1: Brightness / black level
Use the black clipping pattern on the AVS HD disc. Crank your back-light up as high as it will go. It makes the flashing bars easier to see. Adjust the brightness until only 17 & up flash. Brightness is set for now.

Quote:
Originally Posted by buzzard767 View Post

There is only one correct black level setting using that pattern - clip 16, see 17.

Actually, the AVS disc is wrong. Every single blu-ray you own will display dithering(plasma) or elevated black level (LCD) if you set your brightness this way.

That test pattern is worthless, as well as the WoW test pattern. Those patterns only work when setting the black level for the black letterbox bars, or a tv that is displaying no signal.

In smooth gradations, like on all film, the settings resulting from those test patterns will results in elevated black levels.

Setting brightness how Joe Kane instructs, and using his smooth grayscale ramp test patterns with the video black indicators are the only way to set brightness correctly. This pattern will also show how the AVS and WoW patterns do not work, as the black level is elevated past the markers.


You lose no detail doing this. Those AVS/WOW patterns just display noise that should not be visible. You should barely be able to see a 11.5 IRE bar(4% above video black), with the traditional HD color bars provided by smpte. Somewhere along the line everyone started setting there brightness so 1% above video black was glowing. In reality you shouldn't see it at all.

Have any of you actually tested your blu-ray discs after you setup your brightness like this? Its a washed image with elevated black levels, always. Then the threads fill up with people saying the display looks washed out, and something is wrong. You want to set's black level as dark as it can be without losing actual detail, not as bright as it can be to ensure you may not be losing detail. You sacrifice color saturation, depth in the image, and contrast ratio just to display noise.

So now we have 3 opinions in the mix.
post #10 of 126
WOW !

I am going to test this this evening and I am going to tell you my results tomorrow

What is the CORRECT plug for Contrast???? Because Joe Kanes' instruct are too subjetive.
post #11 of 126
Quote:
Originally Posted by redwolf4k View Post

Actually, the AVS disc is wrong. Every single blu-ray you own will display dithering(plasma) or elevated black level (LCD) if you set your brightness this way.

That test pattern is worthless, as well as the WoW test pattern. Those patterns only work when setting the black level for the black letterbox bars, or a tv that is displaying no signal.

In smooth gradations, like on all film, the settings resulting from those test patterns will results in elevated black levels.

Setting brightness how Joe Kane instructs, and using his smooth grayscale ramp test patterns with the video black indicators are the only way to set brightness correctly. This pattern will also show how the AVS and WoW patterns do not work, as the black level is elevated past the markers.


You lose no detail doing this. Those AVS/WOW patterns just display noise that should not be visible. You should barely be able to see a 11.5 IRE bar(4% above video black), with the traditional HD color bars provided by smpte. Somewhere along the line everyone started setting there brightness so 1% above video black was glowing. In reality you shouldn't see it at all.

Have any of you actually tested your blu-ray discs after you setup your brightness like this? Its a washed image with elevated black levels, always. Then the threads fill up with people saying the display looks washed out, and something is wrong. You want to set's black level as dark as it can be without losing actual detail, not as bright as it can be to ensure you may not be losing detail. You sacrifice color saturation, depth in the image, and contrast ratio just to display noise.

So now we have 3 opinions in the mix.

I'm skeptical of your claims since it goes against all conventional wisdom. How many experts agree with this advice?
post #12 of 126
Quote:
Originally Posted by PlasmaPZ80U View Post

I'm skeptical of your claims since it goes against all conventional wisdom. How many experts agree with this advice?

I know...and thank you for not flaming.
post #13 of 126
We have a couple of issues

-Setting black level on displays that don't have a floating black level (LCDs).
-Setting black level on displays that do have a floating black level (Plasma).
-21 point or LUT based black level.


If the black level does not float, then code 0 and code 16 should produce the same luminance level.

If the black level does float then you should use a pattern that has a medium APL and set the brightness so code 0 and code 16 have the same luminance level.

Of course to do that accurately you need a meter that can read those very low light levels.

The overriding issue is that since we don't always have control over gamma, it's more important not to crush 4% than to have the ultimate black level. So if we have gamma control at 5%, then you can set it with a meter so that we have the correct luminance ramp up out of black. If we don't and we are crushing those first few steps, then you have to compromise.

As always the issue is how to compromise when displays don't work the way we'd want them to work in a perfect world.
post #14 of 126
A data point
code 17 at 2.2 gamma = 0.000709%

If you have 35fL at 100%, then 17 should be 0.000248fL.


Depending on a lot of conditions that may be below the threshold of perception. Granted we are typically talking about 1 or 2 clicks of brightness between where black disappears and when it actually is the same as 0.
post #15 of 126
Quote:
Originally Posted by PlasmaPZ80U View Post

I'm skeptical of your claims since it goes against all conventional wisdom. How many experts agree with this advice?

I completely agree with wolf. You use the DVE Grayscale ramps with the 2 dots at the end. You adjust brightness to the point where the dithering or stepping is at the 2 dots and your done.

The AVS disc with flashing is no good especially if you use the 17 number. The 19 sounds like that may be correct as per these new istructions I hadnt seen before.

Anyway I double checked wolfs method and he is correct spot on 100 percent true.
post #16 of 126
Quote:
Originally Posted by PlasmaPZ80U View Post

I'm skeptical of your claims since it goes against all conventional wisdom. How many experts agree with this advice?

Strictly-speaking the application portion fits with the instructions from Digital Video Essentials. The first level above black on their pluge is 2%, which I believe is luma 20. On some displays it is very easy to see the display's black and the darkest levels the display can create, especially close to the screen in an unlighted room. In certain conditions, it's possible to hard-clip everything below 2% gray and fit with their audio instructions. Like Sotti mentioned, there's not a lot of difference between video black and 2% in terms of display gamma math. I'm not convinced Digital Video Essentials necessarily intends to always cut off 17-19 gray luma, but their audio instructions support the position with some displays or viewing conditions.

My opinion is that black-level is a very simple control; it generally just changes where the display's black ends up in relation to video information. Generally any video information below the display's black is lost. Any information above the display's black will be reproduced according to the on-screen gamma produced by the display, and some displays may even have controls to affect on-screen gamma, or how the levels above the display's black are reproduced. Assuming you intend to watch the display from a certain distance, the only real variables are room lighting and other on-screen video levels. Generally more light in the room, or a brighter on-screen image, will tend to make near-black levels harder to discern. I'm not convinced that gray luma 17-19 is mere noise on the images I've looked at, so I tend to lean toward setting the display's black at video black (16 luma) and using room lighting to try to cover any display deficiencies. Some digital displays with poor black or near-black performance may have a better subjective appearance if you choose a compromise such as cutting off information above video black, like advocated by the Digital Video Essentials audio instructions.
post #17 of 126
Quote:
Originally Posted by serialmike View Post

I completely agree with wolf. You use the DVE Grayscale ramps with the 2 dots at the end. You adjust brightness to the point where the dithering or stepping is at the 2 dots and your done.

The AVS disc with flashing is no good especially if you use the 17 number. The 19 sounds like that may be correct as per these new istructions I hadnt seen before.


I would appreciate it if someone could explain this method of adjusting brightness in some more detail. A simple step by step approach would be great. I don't understand what "dithering or stepping" is referring to. I think it would be interesting to see how this method compares to the other method that I have used which is AVSHD. Thanks.
post #18 of 126
Thread Starter 
Well, after all the discussion, I popped in the DVE grayscale ramp to compare with what I ended up with using AVS HD, and I could see no discernible difference between the two - YMMV.
post #19 of 126
Quote:
Originally Posted by Razz1 View Post

I would appreciate it if someone could explain this method of adjusting brightness in some more detail.

It's from Digital Video Essentials, and the following fits with my memory:

Quote:
Originally Posted by redwolf4k View Post

make the 2% above video black bar disappear, and then increase brightness until it just appears. He then explains you should barely be able to see the 2% above video black bar, it should be "hard to see against the black background".

You can probably do the same thing with the APL Clipping pattern. Pause the disc to stop the flashing, so that you can see the vertical bars. Start by setting brightness much too low to get rid of most of the bars. Turn up brightness to the lowest setting where you can just barely see the bar marked 20.


Quote:
Originally Posted by duke32 View Post

Well, after all the discussion, I popped in the DVE grayscale ramp to compare with what I ended up with using AVS HD, and I could see no discernible difference between the two - YMMV.

Depending on room lighting, my display can result in a few clicks different brightness in going with the Digital Video Essentials instructions, but of course Avia doesn't exactly match Digital Video Essentials either. On my TV with proper room lighting, the difference in not clipping 17-19 is very subtle. Really it just depends how quickly the display comes out of black and room lighting.
post #20 of 126
Quote:
Originally Posted by alluringreality View Post

You can probably do the same thing with the APL Clipping pattern. Pause the disc to stop the flashing, so that you can see the vertical bars. Start by setting brightness much too low to get rid of most of the bars. Turn up brightness to the lowest setting where you can just barely see the bar marked 20.

Is this APL pattern applicable to LCDs where all of the "extra and dynamic stuff" is turned off? I had thought that the APL side of things wouldn't be important for this type of display and these settings.
post #21 of 126
The clipping and measurement patterns are unrelated. The APL Clipping pattern is covered in the manual, but using it without any flashing is more similar to the Digital Video Essentials standard pluge. Displays with backlight or iris controls can work like duke32 was talking about, some displays may have gamma controls, or room lighting can also affect near-black perception.
post #22 of 126
I have an interesting thing to add. I've set black level for my Panny PF11EK commercial display and I checked it at least 5 times.

I had to adjust the white balance (low) for red to minus 2 in order to eliminate faint red flecks/spots/dancing pixels in video level 16. Video levels above 16 exhibited many many green flecks (and a fair amount of red flecks, I could not spot blue one's). Actually, all those levels above 16 were not really clean. They were grey but the dithering clearly had the upperhand. It kind of looked terrible.

But, the AVS dics said it was fine so I popped in a film (Season of the Witch). The dark scenes were riddled with green flecks. Obviously, I could not see them 2.5 metres away, but coming within +- 30 cm they were very easy to spot. So I set the brightness down a notch and the picture improved (being subjective here) as the green flecks got less obvious.

According to the AVS dics, I move black ground to video level 18.


In light of the above, I'm taking redwolf very seriously. Is dither really so bad on these plasma's. It really bothers me a lot!
post #23 of 126
Quote:
Originally Posted by Jeroen1000 View Post

I have an interesting thing to add. I've set black level for my Panny PF11EK commercial display and I checked it at least 5 times.

I had to adjust the white balance (low) for red to minus 2 in order to eliminate faint red flecks/spots/dancing pixels in video level 16. Video levels above 16 exhibited many many green flecks (and a fair amount of red flecks, I could not spot blue one's). Actually, all those levels above 16 were not really clean. They were grey but the dithering clearly had the upperhand. It kind of looked terrible.

But, the AVS dics said it was fine so I popped in a film (Season of the Witch). The dark scenes were riddled with green flecks. Obviously, I could not see them 2.5 metres away, but coming within +- 30 cm they were very easy to spot. So I set the brightness down a notch and the picture improved (being subjective here) as the green flecks got less obvious.

According to the AVS dics, I move black ground to video level 18.
Is dither really so bad on these plasma's. It really bothers me a lot!

I don't think you're supposed to mess with the low end grayscale controls for what you describe. Without a meter you could be making dark to mid grays much worse (low end settings are typically on the coarser side making each click pretty significant).
post #24 of 126
It was either that or lowering brightness so that the red flecks moved to level 17. I could kept doing that but lowering what I said actually got rid of them. I will own a meter soon (I need to convince someone hehe) and then I'll be able to tell whether I messed up something by using that control.

Truth be told, I do not know the impact of the control. I just made a 'smart' guess.

edit
still, regardless of my tinkering with the white balance control for red, the dithering is much much too obvious for my taste. Lowering brightness and thereby clipping black a little indeed gave a less washed out picture. You see, standard pluge patterns have 1 big issue: I can make the below black bar go away, but between making it go away, and preventing above black to go away, are a certain number of clicks (3 for my plasma). Most explanations tell you to stop as soon as black ground (= background of the pluge pattern) is as black as the below black bar but this results in dithering. That is, if dithering is what I'm seeing:-)

Isn't there really a dummy proof way to go about this? Someting with absolute numbers instead of bars?
post #25 of 126
Quote:
Originally Posted by Jeroen1000 View Post

It was either that or lowering brightness so that the red flecks moved to level 17. I could kept doing that but lowering what I said actually got rid of them. I will own a meter soon (I need to convince someone hehe) and then I'll be able to tell whether I messed up something by using that control.

Truth be told, I do not know the impact of the control. I just made a 'smart' guess.

edit
still, regardless of my tinkering with the white balance control for red, the dithering is much much too obvious for my taste. Lowering brightness and thereby clipping black a little indeed gave a less washed out picture. You see, standard pluge patterns have 1 big issue: I can make the below black bar go away, but between making it go away, and preventing above black to go away, are a certain number of clicks (3 for my plasma). Most explanations tell you to stop as black ground (= background of the pluge pattern) is as black as the below black but this results in dithering. That is, if dithering is what I'm seeing:-)

Isn't there really a dummy proof way to go about this? Someting with absolute numbers instead of bars?

I don't think whatever you're trying to achieve falls under the category of calibration. It seems more likely to me that you're noticing something you don't like that your plasma does on black or near black screens and then messing with the low end white balance to make it look 'right' to your eyes.
post #26 of 126
Quote:
Originally Posted by Jeroen1000 View Post

It was either that or lowering brightness so that the red flecks moved to level 17. I could kept doing that but lowering what I said actually got rid of them. I will own a meter soon (I need to convince someone hehe) and then I'll be able to tell whether I messed up something by using that control.

Truth be told, I do not know the impact of the control. I just made a 'smart' guess.

edit
still, regardless of my tinkering with the white balance control for red, the dithering is much much too obvious for my taste. Lowering brightness and thereby clipping black a little indeed gave a less washed out picture. You see, standard pluge patterns have 1 big issue: I can make the below black bar go away, but between making it go away, and preventing above black to go away, are a certain number of clicks (3 for my plasma). Most explanations tell you to stop as black ground (= background of the pluge pattern) is as black as the below black but this results in dithering. That is, if dithering is what I'm seeing:-)

Isn't there really a dummy proof way to go about this? Someting with absolute numbers instead of bars?

what your doing is a correct thing to do but But, you should have a meter to make sure the grayscale is correct. If your tv wasnt accurate to begin with though and your just getting rid of the flecks then your fine anyway. I had this same thing on my set. It causes the noise in the ex500 sets that sometimes reviewers that don't know what they are doing when they calibrate the set see.
post #27 of 126
That may very well be the case. I wonder if I could take a picture of it; I'll try when I get home tomorrow. But, redwolfs description does describe what I'm seeing.

It kind of looked like when you choose pc levels instead of video levels. The overall image just looked too bright aka washed out. The Chromapure manual also seems to use a pluge pattern to set brightness. That's not really an improvement

edit: redwolf, feel free to post an accurate step by step for setting brightness. I can then decide for myself what looks best. I'm not an expert but its hard to miss the improvement on my screen when I clip black just a bit.
post #28 of 126
I'm willing to give this new approach a try on my LCD. Which pattern is best from the AVS disc (I don't have DVE) and how should I use it?
post #29 of 126
Quote:
Originally Posted by PlasmaPZ80U View Post

I'm willing to give this new approach a try on my LCD. Which pattern is best from the AVS disc (I don't have DVE) and how should I use it?

I just checked the avs flashing disc pattern again. It coincides with seeing 19 flash.

So either use the DVE grayscale with the 2 dots. And lower brightness till dithering or banding is visible at or a hair below the 2 dots or use AVS and use 19 instead of 17. the 2 dots test will require you to get up to the set not from 10 feet back. though technically so will the avs pattern.

That will get you proper brightness and detail.

The odd thing about this is at least on my lcd I used to have so many issues with shadow detail. I feelt like i wasnt seeing it because I could see faint information. Turned out that was not detail but noise. And Getting this right as it is now hides the noise and the areas such as dark clothing for instance are now jsut blank black areas but now my mind isnt annoyed with the image thinking I should be seeing detail. It fells right and looks great and the set just pops.
post #30 of 126
I'm wondering whether 19 or 20 is the one to focus on, since gamma can affect which coincides. I just did it with the APL Clipping Pattern at 20 just visible (as per alluringreality's advice). Brightness went from 43 to 40 (and Contrast from 99 to 100).
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