For those struggling with brightness, contrast & backlight settings on LCD's - Page 3

I'd like to see what professional calibrators say about this, some patterns say 17 is right and other patterns say 19 is right. Who is right and who is wrong?

I dont contest your results with that equipment. I do however ask then how with avs disc set to 19 I can see the lowest sshadow detail box on DVE, THX and 2 other test patterns I have. Tested now on a 55ex500, 52v5100 and a 32xbr6.

I am not crushing black on my set with this method. However using 17 I am indeed washing out the image and making it to bright.

In fact as far as visual watching goes I was watching harry potter half blood prince (about as good a shadow detail test as thier is in a movie) and I saw things I never saw before. In this case it was because of the pop from a properly set black level. Where my eye didnt catch things in the background before because of the flat washed out look previously.

Perhaps its an LCD thing. Though I do not like that you say your set loses light output due to the brightness control. It really shouldn't. That means your sets adjustments arent working as they are supposed to.

It's relative

Einstein

To be completely clear, I totally agree that when setting your black level to "19" that there is in fact information being clipped. The initial point however was that when playing actual content, like a blu-ray disc (on the device the patterns were used on) when setting the black level to "17" the blu-ray discs video black actually dithers, and it is not supposed to. Upon further investigation with that film source, there is no benefit to leave that dithering there, all it does is wash the picture because video black is elevated. The real question is "what is there to gain @ 17 besides noise?" I understand the point made earlier about an extremely bright room however.

For some reason many of us are finding that blu-ray discs seem to align with the DVE ramp indicators (which is the equivalent of the AVS disc set @19.)

If AVSHD 17 is true, and I have no reason to believe (other than your theory) that it isn't, and you can't see 17 & 18, 17 & 18 are crushed.

I have a VT30 and several LCDs, both LED and CCFL backlit, scheduled for the next month. I'll set video level 19 as minimum visible and take a look at my reference material....

So, are you a pro calibrator?

Good deal. I know forums dont convey what people write properly all the time. I'm not against you here. Just want to figure out why this is.

Perhaps on my set it is an issue because Im using the MP4 versions thru the ps3. I just dont know.

Your post wasn't up when I was making my previous one. The original intent on the thread has been blurred. I have a Panasonic VT30 calibration coming up after a tech makes the latest "fix". Panny has just started (2 days ago) sending techs out with memory sticks because a firmware update won't do what needs to be done. The EPROM has to be flashed. Anyway, the VT30 owner reports heavy dithering so I'll have an excellent opportunity to see if raising the black level from what I use as standard both reduces dither AND does not crush blacks.

I calibrate for beer - true statement.

I've been calibrating for a year and a half and will be picking up my THX video calibration certification next month in Indianapolis after CEDIA. In November when I'm back in Florida I'll work for money. There are no THX or ISF certifications in my area and there are hundreds and hundreds of high end home theaters.

Later - or I'll miss my tee time. Retirement is good.

I love this. Maybe some day the same will be for me.....

So theory, that level 16 is reference black and we should see 17 and up, apparently is not agreeing with practice and our eyes. Crushing near blacks gives me a better picture. We just don't know why that is do we?

Moreover, my video black does not dither at level 16! BUT there is excessive dither througout the picture that is annoying (in black area's that are not level 16). So I also very much prefer to set it at level 19 for the time beeing.

Has anyone considered there may be more variables at play that cause the dither (for plasma's then). Like gamma and what else I might not know about?

Are the ppl here that have their set pro calibrated? They could stick in the AVS dics and take a look what it says.

By dithering, do you just mean excessive noise?

Yes, most notably the famous green noise. When black is set at 16, it encompasses the picture like a haze. It's like looking at the tv from behind a fence. Note that I can't see it from my viewing position, from there I can only observe that I have a washed out picture.

I do wonder if there is a gamma issue between choosing 16 or 19 as the black.

Some screens do better and others worse? Meaning some screens might get 16 black right but 17+above go up too steep which results in washed out black detail? By rising black to 19level the steep rise vanishes away into the black crush and we keep the smoother plane from above to produce better blacks?

I currently have been using a 16 black level for myself and tuned myself to that setting manually.
I tried the 19 level just now by adjusting my brightness setting but I didn't like the gradient curve I got. Basically my screen clipped away at the lower levels but kept the strength of the higher grays the same which resulted in a damn quick rise from black to the darker gray->gray. I like the smoother gradients I get with the 16 level with a few extra darker nuances.

I reckon many here who prefer 19 could try a lower gamma point in the lower parts with 16 instead. (Presuming you can adjust gamma in the detail needed to adjust the lowest gray scale points only.)

I think there is something to this. All the sony's I have dip high in gamma at the low end. almost 2.4. I started setting gamma on them to +1 (especially the v5100 and the ex500) with brightness down to 49 to compensate. This made the gamma run at 2.2 at 10 ire and around 2.1 at 100 ire. This helped the image in the shadow area look less saturated and less overdarkened(for lack of a better term). So with that I set to 19 and bam I see all the detail Im supposed to in DVE and THX and other patterns. Everything lines up as it should.

If I didnt do +1 gamma I need to do 52 brightness at 16 wash the image out and see "dithering detail". Its detail that I should not see. For whatever reason its easy to see its noise especially on the lcd I just tip sideways and you see its blotchy noise not detail.

I feel there is something to the gamma causing the discrepancy. Perhaps even relation to LCD and design to squeeze more black out of them.

Either way the image is excellent set the way I have it. It adheres to industry standards properly. I get superior black levels .009 set this way, and I see all proper shadow detail.

Interesting discussion, thanks guys!

Sounds like you boys need to get some of this.....

Nah gamma is fine long as its between 2.35 and 1.8. As AVS says gamma is a love the one your with thing. Gamma is more of a from a crt days thing than now.

No need at all to get bent out of shape for a super flat line.

Read carefully. All of it. Especially the part about crushed blacks!!!!!

Tom Huffman:

The gamma of your display should be between 2.2 and 2.35.

The gamma curve should be smooth and consistent. The curves presented in the chart above are idealized gammas. In the real world displays can create a gamma curve that varies considerably from this ideal.

The gamma of red, green, and blue, should all be the same. If they are different, then you will have a problem with grayscale tracking.

You can change system gamma by adjusting the contrast and, especially, the brightness control. If you lower the brightness control too much in an effort to maximize contrast, then you will get an excessively high gamma and crushed blacks with very little shadow detail.

Because of gamma, 50% input does not produce 50% of available light output. To get 50% of available output, you need a signal input of between 70-80%.

Getting gamma right is important not only because you want to achieve a balance between shadow detail and high contrast. A flat gamma response (the same gamma at each level of stimulus) in the correct range will help to provide the image with great depth and realism.

You mean the luminance curve?

19 is supposed to remain flashing/visible so 18 becomes black, not 19.

Generally changing a brightness control doesn't significantly affect 'display gamma', or how the display changes light output near 'display black' (darkest possible shade). The first video level above 'display black' will typically be produced at the same light output difference, regardless of the brightness setting. Say you have two scenarios:

1) The first video level above 'display black' is 17.

2) The first video level above 'display black' is 20.

Most digital displays will have the same light output in #1 for 17 that it will have in #2 for 20.

This is generally what the DVE test is based around. The video black background from the DVE standard pluge is 16 and the first level above video black is 20. By aiming for a subjective difference between 16 and 20 their instructions essentially open the door for 17, 18, 19, or 20 to be the first level above 'display black'. They're generally aiming for a low setting, so things such as the display performance near black, room lighting, and viewing distance determine where 'display black' actually falls below video level 20. Most other commercial calibration patterns for setting brightness use a lower first video level above video black, rather than the 20 used in DVE. With typical viewing distances and room lighting, generally a changing video level is easier to spot than a static difference, so often flashing 16-19 appears about as easy to notice as a static 16-20.

Here are some possible reasons why setting 'display black' at video black (16) may not be subjectively similar to the DVE instructions:

- 'Display black' is not very dark
- First levels above display black are a significant change from 'display black' (very low gamma near 'display black')
- Very dark room, or little room lighting
- Short viewing distance


Yes, for most of the people carrying on the discussion it would be preferable if the display could come out of 'display black' more slowly. Generally it would be ideal if 'display black' was set at video black (16) and the electronics could be adjusted to come out of black at various rates to account for most of the items mentioned above. Assuming a display had this much control, in the prior scenarios #1 & #2 then video level 20 could have the same light output difference above video level 16, regardless if 17-19 were displayed or cut off.

Isn't 19 the corresponding value to keep barely flashing, not 20?

The quoted portion mainly addressed the Digital Video Essentials standard pluge, which has no flashing, and the first level above video black in the DVE pattern is 20.

It seems many other posters repeatedly referenced 19 flashing/visible as the corresponding value for the AVS disc after using the DVE pattern. Could gamma influence this difference?

Flashing is simply alternating between two video levels, and the flashing 19 on the APL pattern is just changing between 16 and 19. The DVE pattern includes 16 and 20 on the screen at the same time. Generally changing between video levels is easier to notice than trying to pick out a non-changing difference. Since alternating levels are usually easier to see, often the flashing 19 looks about like non-flashing 20.

Light output change (gamma) between display black and the first level(s) above display black will vary between various displays. For most displays with good performance it should be rather difficult to spot a change of one video level, even with flashing. Being near the display in an unlighted room there are certainly displays where it's possible to spot the difference between the display's black and the first level above display black. On my LCD from years ago it was easy to see when 20 was either displayed or cut off on the DVE pattern in a dim room, because the first level above black was significantly brighter than black. Various displays may come out of black at different rates, and with poor enough performance flashing 20 might be required to fit with the DVE instructions.

I'm going to view some content for a few weeks (before I spend more time tinkering than watching)and in the meanwhile order my Xrite meter. I'll have some results in the near future. May I ask you guys to most the meter you own? I'll post measurements once I'm confident I've got them right. In the meanwhile I'll get some picture where hopefully the difference in dither can be seen.

I'm getting this one:

• ChromaPure Version 2 Standard & upgraded i1 Display Pro OEM

Stay tuned for pic's tonight. This might give a more "visible" dimension to my observations.

Thanks for this explanation made it much clearer in my mind on how this should be and works.
I changed my settings slightly thanks to this or went back to a older setting which I actually made first in regard to gamma adjustments I have made with my screen.

Reading this thread if I haven't got it completely incorrect, people seem to argue we get better "reference" blacks/shadow detail if we follow the instructions for the DVE pattern right?
Meaning we aim for 16-19 looking black and 20 having a shade of gray? (though you don't need to crush 16-19 to black but there can be darker shades but at normal viewing it should look near black non the less? and 20 looking like being the next actual step? If I had a calibration tool it would have a specific light output right there at 20? 17-19 could have some shades in between if I feel like it unless I crush them away?)

If following the other way we had black at 16 and then 17 has the same light output as 20 would have with the DVE pattern?
I can clearly see how this would give a completely different look and be too sharp a jump from black as some would suggest. 20 in this case would be a few shades brighter as will as will a whole slew of shades of colors would be.
Meaning we get detail that should not be seen.
Maybe there is a misunderstanding about the target somewhere in the guides or bad wording or people just misunderstanding? for which levels one should have at each point or aim for.

It seems like AVSHD and DVE explain different targets looking at this thread.
AVSHD adhering to a 16 black and a set shade/light output for 17. While DVE has the same light output shifted up to the 20(19) spot as target?
The diffrence would be much brighter image for AVSHD and darker for DVE. Though not following the guides one could use either pattern to end with same target if same instructions applied?

I would tend to split black from shadow detail:

Generally a digital display will have a darkest possible shade, or display black, where it produces no image for any video information received. The brightness control just assigns what video levels are used for the display's darkest shade. Going back to the previous scenarios, in #1 & #2 video black (16) is likely to be the same shade in both. In #1 all video information from 1 to 16 is at display black, and in #2 video information 1 to 19 is at display black.

In order to have 'shadow detail' you have to have a difference in light. For gray the TV has to produce two different video levels with non-matching light output in order to create an image. In #1 the video levels 17 and higher should generally be reproduced at non-matching levels, and in #2 video levels 20 and higher are likely to be reproduced at non-matching levels. This difference in where the display begins producing an image is really the only significant item in the off-topic discussion.


Primarily all that's being talked about is where to set the first displayable level in the 17-20 range. That's no more than a difference of 3 video levels. While some meter and display combinations can return a value for display black and levels above the display's darkest image, it's not common to use measurements in this range.


Yes, this is reasonable. Primarily I'm saying that everything above display black is just going to be reproduced according to however the display operates. Some displays like duke32's have more than one control to affect near-black operation, and room lighting or viewing distance affects perception. The DVE audio instructions allow for cutting off a few video levels above video black to fit with their subjective test. The DVE audio is merely an opinion for a best-fit solution, and other commercial brightness patterns do not necessarily share gray luma 20 as an unequivocal first displayable level above video black. For example the instructions at http://www.spearsandmunsil.com/artic...sscontrol.html seems to use 17 for DLP and 20 for other displays. I'm almost certain the first level above black on the original Avia disc was lower than 20, and apparently WOW also suggests using lower than DVE's 20. One general complication is that displays simply do not all operate identically. If you wish to consider the DVE instructions as a minimum and the 17 & up as a maximum range that would be reasonable. In certain cases a change of 3 video levels is going to be very difficult to observe, and some display and viewing combinations work so that the 17 & up test also fits with DVE's subjective test, but such a thing is highly dependent on the display and viewing conditions.

I second that. The 3 levels difference on my display are very easy to observe. Even my non-techie folks here can spot the very obvious change in dither. I did have to point out the washed out image. To them it looked normal, but setting it at level 19, they did agree it looked more pleasant. To avoid confusion, I'm going to keep repeating that video black on my display is dither free, no matter which level I pick (16, 17,18,19...). With real film content however, 16 makes that green dither is all present and annoying. Level 19 makes the picture far more pleasant to watch.



Can we agree then that we are all a bunch of perfectionist hair splitters

edit: sorry guys, picture time failed. My camera is not up to the task and blurs the image in the darkened room a lot.
I'll try again with some more light...

So is having 19 flash correct on the black clipping pattern and apl clipping pattern?