Blacker than black level on PHD7 - No Pluge (DVE) on VGA input

Eye in the sky

Standard Member
Does anyone know if one can adjust the Blacker than Black (BTB) level on the 42PHD7? There is always a visible black background, not totally black like if the plasma is off, but slightly bright. Think it may be at level 16. This happens on VGA input and also on BNC component.

Pluge is not present when using DVE (only two inner black bars not all three
black bars, ie not outer 'blacker than black' black bar).

Does anyone have this problem? Anyone knows how to adjust the plasma to output blacker than black?

I am sure someone must have asked this. I searched the entire forum but I can't find any discussion close to this.
 

richjthorpe

Active Member
Some DVD players are incapable of displaying the lower end blacks and so on DVE or THX optimiser, it tells you to set the brightness to that where the lowest black dissappears and the set it one darker.
 

Piers

Active Member
Eye in the Sky,

Picture settings menu, advanced settings on, black extension - make sure it is all the way to the left of the scale. Are you now seeing blacker than black?
 

Eye in the sky

Standard Member
Piers, richjthope,

Black extension is already on the left but still no pluge. I had the DVE in my Denon 3910 where its SETUP was set to 0 IRE. And from 3910 to iSan HD+ to PHD7. No plunge even if the 3910 is directly connected to the BNC components of the 42PHD7.

I dont see BTB on the 42PHD7 in that the dark background always have some 'brightness' to it, ie its visible and not DARK DARK, and NOT entirely black like it's been turned off.
Unless I got the idea of BTB incorrect. What's the definition of BTB? In my opionion, BTB is at level 0 or REAL 0 IRE or ZERO mV, or TOTAL darkeness as if the display's been turned off.

I think the 42PHD7 black level is set at level 16 even if the VGA input is at 0 IRE from the 3910. Piers, do u get this? This can surely be calibrated on the 42PHD7 right, via the service menu. Piers, do you think you can kindly try this and post your findings here.

I really need to know if the PHD7 can be calibrated to display BTB, ie level 0 and 0 mV.

Cheers!
 

pjclark1

Well-known Member
Black level also appears to be different between NTSC and PAL
My philips dvd recorder has a setting "adjust black for NTSC"
 

Piers

Active Member
Eye in the Sky,

The reason that I asked you to check the black extension level was that I found exactly the same as you have found when I calibrated a customer's panel earlier this week. You have that setting correct.

He had the same set-up as you, though the DVD player was different. I inputted the pluge pattern from my signal generatorto the HD+ and couldn't get anything blacker than black to display (I would define BTB as anything between 0 IRE and 7.5 IRE). But, using the test pattern from within the HD+ the BTB bars were showing and I ended up having to calibrate using these.

Back home with Denon 3910 to Lumagen DVI to PHD7 I am seeing BTB from DVE (provided the Denon is set to "normal" and not "enhanced"). For optimal PQ (to overcome the "black isn't totally black") I am backing off brightness by a couple of clicks more than the pluge might suggest as being optimal - and it works here!
 

imichael

Standard Member
You can also use the first screen in the advanced picture resolution settings on DVE. I use this screen as a final check now. the black to white progression goes around the centre inage, and the final white and black blocks both have a 5% (I think) lighter or darker square inside.
 

Pottsy

Active Member
EITC, hello again!

It was my screen that Piers calibrated. Couple of points - it sounds like you may be hoping for the BTB bit to be blacker than the blackest that the screen can show - obviously it won't be, the blackest you'll ever see is the same as when you turn the brightness right down on the panel, when displaying a black pattern.

What shocked me was how hugely interactive the brightness and contrast are. Do NOT just set the brightness and then fiddle with the contrast. Go back and forth. After Piers worked his magic, you can just see the 2 black bars and 2 white bars (Iscan pattern), which is as it should be. If I whack up the brightness, I can see the BTB bar (so yes, it does pass BTB).

EITC, some funny things came out of the calibration, given that Piers has the same screen. Like what was correct on his, was not correct on mine. They are all different. So posting my settings will almost certainly send you the wrong way. I would suggest spending the £ and get it done. Make sure you have coffee in, and the results are very worthwhile. My colours now are, well, I don't notice them (if you see what I mean). And I was getting plenty of black crush, which has now gone. Dark scenes are now detailed. My gamma is now correct. And so on...

Just watched Sharks Tale (R1). No need for HD for me!

Andrew
 

Pottsy

Active Member
BTW, I've just had a look at DVE (PAL) pluge, and it passes BTB perfectly. So either it's the component inputs on the HD+, or (sorry Piers) the signal generator... More emails to the manufacturer maybe?
 

Eye in the sky

Standard Member
Guys ...

So ... do you all concur that even when your plasma is showing BTB, the screen still shows a certain level of brightness, at a few mV above 0mV and not at 0mV, at least above 0 IRE and not exactly at 0 IRE. So the effect of BTB is not as if the screen is turned off, right?? Do you guys concur with this? OK OK ... a simpler way to define BTB is ... BTB is when all guns have been turned off ie R, G and B guns are at level 0. Do you guys agree?

If the latter definition for BTB (all guns off) is correct, then what I observe on the screen when all guns are turned off (via PHD7 service menu) is that there is actually still some brightness on the screen, at least a couple of mVolts, or above 0 IRE. Does any of you get this at all?

Would be great if Piers or Pottsy can check this out and post here.
 

Eye in the sky

Standard Member
Piers and Pottsy::
You mentioned that your HD+ was showing BTB (3 black bars) on the PHD7. I had to have my PHD7 brightness up to 15 and contrast at 0 to see it. At this setting, when you look very close at the blackest bar (outputting BTB level), you will still see some output from the RGB guns. The guns are not totally off! Why can't all the guns be turned off so that BTB is strictly at ZERO mV.

I need to know this. Setup your DVD (DVE), PHD7 and HD+ to display BTB. Move closer to your screen and see if there is any output on the BTB bar. Do this for DVE>PHD7 and HD+>PHD7. I suspect there will some ouput of RGB for these two scenarios and not totally black black. Pls post your results here. Thanks.
 

Pottsy

Active Member
EITC,

An understanding crisis I suspect here!!

The plamsa has a brightness that is the darkest it can display. This still has a certain brightness, as you have noticed. You cannot get any darker than that, owing to the way plasmas work. For this discussion, we shall call this almost black "plasma black". Look at a nasty plasma, and this plasma black is sometimes quite bright. But whatever it is, it is a limitation of the hardware. No magic, nor signal, can reduce this latent glow.

Next issue, BTB.

Black in a signal is sent at a certain (weak) signal strength (let's call this signal strength 7 out of 100). So it is possible to have a weaker signal, say 0 or 2 or 4, that could represent "BTB". But in a movie, when black is shown it comes out as signal 7. So we want to set the plasma so that "plasma black" is displayed at signal strength 7. If we can see signal strength 6 or less, then we are not set right, and we can see the BTB bar. When set right, the black background and the BTB bar are all at "plasma black".

If you turn the brightness up lots, and you can see the BTB (third) bar, then your screen in recieving BTB. So now set the brightness and contrast so you can see 2 black and 2 white bars. Remember I said they were interactive? Go against the flow of common advice and turn up the contrast to 5. Now play with the brightness and see if you can see 2 black and 2 white. If I go to brightness 6 or 7 (with the contrast at 5) my BTB bars just start to show. With contrast at 0, I get good black settings but poor white bars.

Or just hire Piers.... One session and your screen is set!
 

Eye in the sky

Standard Member
Thanks Pottsy! It seems that plasmas can never (at least for now) display at 0mV (even when required to). Even at 0 IRE, its still a couple of mV of brightness to the display. In this case I think we can all agree that Panasonic plasmas produce the best and darkest 'plasma black'.

##
Which brings to the conclusion that 'plasma black' is the blackest of the BTB range. But in this case, there is still a latent glow of a small amount of brightness to the display.
##

I am still waiting for my DVI blade. Till then, I think this is also true for digital DVI output that at level 0 (lowest in the range of 0-255 for 16.77 million colours) is never at 0mV at the RGB guns to the display.

By any chance, did you have check with setting all guns to off (IIC service menu>All guns>7 (all off)), if there is visible light on the PHD7 display. I checked mine last night, it indeed has some light even though all guns are off.
 

Pottsy

Active Member
? ... :)

The blackest it can display should be set to video black. BTB must not display any darker. Otherwise blacks on input sources will not display as black.

There is nothing that can be done to make the display blacker (other than switching it off). And no, never seen the need to turn the guns off. DVI input will make no difference either (other than being stuck ay 60Hz).

Which brings to the conclusion that 'plasma black' is the blackest of the BTB range.

No, this should be regular video black, not BTB.

Simply make sure you can just see the 2 dark bars, and not the third (BTB) bar. Job done! (Apart from making sure you can just see the 2 almost white bars....)

Then play the DVE pluge and set the brightness on the Iscan so that you can't quite see the BTB bar from the DVD.

FYI, my settings are:
Panasonic: Brightness +5, Contrast +5, Gamma 2.2, Pic Normal / Warm
Iscan SDI input: Brightness -1, Contrast 0
 
B

banks

Guest
I have a 50PHD7 that seems to have higher-than-expected "plasma black" levels. Even with no input selected, or with black bars displayed, there is a certain amount of light emitted from the display. I have read this thread and understand that a plasma display will always emit some amount of light.

The odd thing that makes me believe that this is a hardware problem is the fact that the glow is only generated by the green pixels. As far as I can tell, the R and B pixels are very close to fully dark, but the fact that all of the G pixels are slightly illuminated gives the screen a slight grayish cast in a dark room, obviously degrading contrast significantly. As far as I can tell, it is the same regardless of input selection (Tried DVI and composite).

I described the problem to Panasonic tech support, and the guy agreed that it sounded like a problem, and that I should take it in to a service center. The problem is that for a display this heavy, it's a real pain to drag this thing off the wall and bring it to the shop.

I found a copy of the Panny service manual for the 50PHD5 (not my 50PHD7) on the web, and was thinking that some of the IIC mode setups might help my situation.

Any advice?

Cheers!
 

Gordon @ Convergent AV

Distinguished Member
AVForums Sponsor
OK alot of confusion here.....

Forget about blacker than black and black etc.....With your plasma you want it to not have any active pixels when it is displaying black...ie you want it emitting minimum amount of light. So....get your DVE or whatever. Stick up the 20ire window with the black bars.

Now turn off the lights and close the curtains.......

Stand right beside the screen and look at it. In the dark vertical stripes can you see that in the darkest one its is made up of flickering pixels? Is the black background around the stripes full of flickering pixels or is it a solid dark colour? Adjust the brightness control down until you cannot see the darkest of the two stripes (we are ignoring the btb stripe). Now turn brightness up one click at a time. When the dark stripe reappears it'll be a random pile of flickering green pixels (there are likely blue and red ones too but you can't see them as easily....if you see red or blue before green then you probably have a greyscale problem as well). Keep going at one click at a time but look at the black background between the two stripes. As soon as you start to see flickering pixels in that black area you have gone too far. So adjust till you get the flicker in the black background then go back one click to remove it and you are done. That is the brightness set. How dark the background is will now depend on what plasma you own. If it's a Panasonic it'll be dark. If it's a Pioneer it'll be grey. This is is harder to do on Pioneers unless it's a darkened room.

Now check contrast then go back and check brightness again....

Gordon
 

gIzzE

Distinguished Member
Excellent post Gordon.
Also adding a scaler, which usually has a lot finer adjustments, means you can get your black level down further, usning the standard brighness setting on the panels remote usually means you have a fairly big jump between getting those twittering pixels from lit to off, to get them off you may have jumped up to far with the brightness, by using the brightness on a scaler you will be able to get them off and the blacks will usually be alot deeper. I say alot, it isn't that much but it makes a hell of a difference to the 3D snap in an image.
 
B

banks

Guest
I agree that btb is moot for my issue, and also admit that my post was a bit OT for the title of this thread. However, the issue that Eye in the Sky seemed to be describing, although mostly unrelated to btb, is pretty much the same as my question.

The core issue is: How much light is typically emitted from a PHD7 when it is properly calibrated and displaying a perfectly black image--how bright is "plasma black" on this Panny?

It seemed odd to me that my "plasma black" is a function of green pixel illumination rather than all pixels. Since I have yet to find a setting--in either the regular or system menus--that changes the minimum illumination level (even when forcing the Green guns off), its down to one of two scenarios: I've either got it as good as the PHD7 can go, or I've got a hardware problem that keeps the green pixels from reaching true minimum illmination.

Cheers.
 

Gordon @ Convergent AV

Distinguished Member
AVForums Sponsor
Absolute black level is a function of ALL pixels not illuminating. Just above black though you'll see green pixels before red or blue in my experience.

If you've done what I suggested then it's as black as it's going to get. Use Cinema or Standard settings when doing it. If you think it's not very black or you always get flickering green pixels then something is wrong.

Mal: No

Gordon
 

Jazz Monkey Jr

Distinguished Member
Gordon @ Convergent AV said:
Now check contrast then go back and check brightness again....

Gordon

Excellent post, thanks.

One more question, which is the best way to set the contrast - I have used the DVE disc but mine looks OK when I set the contrast high, it shouldn't really be over 50%, should it?
 

Gordon @ Convergent AV

Distinguished Member
AVForums Sponsor
Using the reverse greyscale ramps on DVE it's possible to adjust contrast so you see them all but still be partially crushing white detail. Really to get better contrast you need some device to measure gamma curve. With devices that can go very bright without crushing detail I usually set them to a light output figure on my measurement device that I have found to look good. There is no point in giving you that figure as it is proprietry to my measurement tool.

Gordon
 

Jazz Monkey Jr

Distinguished Member
Thanks Gordon,

Obviously I would love to get it ISF's, I have over 200 hours on it now.
I am a bit wary from the comments Piers made about calibrating these, I don't see any point spending the money if the service menu doesn't let you get the settings spot on.

What sort of improvements have you seen on the old Vieras?

Could you not offer a 'mini' ISF for non-panel owners, as I assume it won't take as long as say a Fuji with a scaler?

Are you keen to play with one of these, or, like Piers, would you rather not?
 

Gordon @ Convergent AV

Distinguished Member
AVForums Sponsor
I believe Piers commented the way he did because he has made a decision not to get involved with calibrating Vierra's. This is nothing to do with the fact they cannot be made to be accurate but everything to do with the fact it takes AGES to do them in comparison to other displays. The reason for this is that in commercial panels you can measure patterns while in the service menu making measurements on the fly and changing parameters accordingly. Then when you leave service menu nothing changes. On Vierra's because they have these three levels of adjsutment, user,serviceone, servicetwo, what happens is that you have to do a full measurement outsde service menu, then go in and make adjustements you think are correct without measurement, then come out and put the display back to your prefferred settings then do a measurement sweep to see how close to correct you now are...then go back in to service menu and make more adjustments....then come back out and put display back to your preffered user settings...then go and measure and see how close to correct you are...then go back in to service menu and make adjustments.....etc. etc until you have got one input and resolution calibrated.

It can take a while. The reality is we should charge more for them not less.

I am keen to play with one but my local Panny/Lumagen dealer doesn't have their demo one at the main showroom just now. I'm also slightly busy with other things. It'll happen though and I'm confident it'll be an aobvious improvement.

Gordon
 

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