WinDAS White Point Balance guide for Sony Trinitron CRTs

XoR_

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Why incorrect?
CRT gamma (~2.5) is result of only natural phosphor response. This is common knowledge.
We can bring average gamma down somehow by increasing black level because of its shape (which BTW is hardly perfect, especially near pure black)

LUT adjustment is ONLY for gamma, to change it, to 'linearize' (or apply different shape)
Gamut cannot be corrected with LUT. For this you need to do 3x3 matrix multiplication (sufficient when combined with LUT) or 3dLUT
Gamma and gamut, there is nothing else reffered as 'color correction'

The fact that WinDAS asks you for calibration at "multiple IRE's" does not mean it can actually use these information to correct gamma in multiple places but because of limited precision of measurement devices with less light hitting it.
If it was possible to get different gamma just by using WinDAS then SONY would use such functionality and make sRGB mode not suck. Each Trinitron in sRGB mode have very high black level - have you ever wondered why?

To date you provided no good hard data to prove WinDAS can do anything else than set ranges for OSD control.

BTW. When I corrected G2 on my Dell P1110 I tested high G2 with low BRIGHTNESS and low G2 and high BRIGHTNESS and both produced exactly the same results and based on this test I remain skeptical of WinDAS magical properties and skipped the rest of the tests I intended to do including WPB.
If G2 and BRIGHTNESS are not basically the same setting then how do I know with 100% certainty which is more optimal for my CRT?
Maybe I should just make blacks to be pure black at BRIGHTNESS 90 and have G2 issue solved for more time by giving myself more range in OSD than aiming for 30?!?
Maybe even low G2 and high BRIGHTNESS is more healthy for my CRT tube in the long run? How do you know this is not the case?

If you believe in things like "WinDAS sets 'optimal' settings and prolongs life of the monitor" then faced with someone who dare to ponder about validity of such claims either show [h]ard facts or do not expect all people to agree just because you do.

I simply remain unconvinced.
Do not claim anything, just far from taking unproven 'facts' as reality just because it is convenient to believe in them.
 

spacediver

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Why incorrect?
CRT gamma (~2.5) is result of only natural phosphor response. This is common knowledge.
common knowledge or not, it's simply incorrect.

Here's a classic read by Charles Poynton (who, incidentally, informed me about five years ago that in 1992 he wrote "what amounts to the preliminary product spec" for the FW900).

Here are a couple quotes:

"The function is dictated by the electron gun and has nothing to do with the CRT’s phosphor"

...


"The nonlinearity in the voltage-to-intensity function of a CRT originates with the electrostatic interaction between the cathode and the grid that controls the current of the electron beam. Contrary to popular opinion, the CRT phosphors themselves are quite linear, at least up to an intensity of about eight-tenths of peak white where saturation begins to set in."


From his website:

"Incidentally, the nonlinearity of a CRT is a function of the electrostatics of the cathode and the grid of an electron gun; it has nothing to do with the phosphor. Also, the nonlinearity is a power function [which has the form f (x) = xa], not an exponential function [which has the form f (x) = ex]. For more detail, read the Gamma chapter in Poynton's book Charles Poynton, A Technical Introduction to Digital Video. Chapter 6, "Gamma" is available online at (Acrobat PDF format, nnn bytes).."

From another source:

"In the early days of television it was discovered that CRT's do not produce a light intensity that is proportional to the input voltage. Instead, the intensity produced by a CRT is proportional to the input voltage raised to the power gamma. The value of gamma varies depending on the CRT, but is usually close to 2.5. The gamma response of a CRT is caused by electrostatic effects in the electron gun"



LUT adjustment is ONLY for gamma, to change it, to 'linearize' (or apply different shape)
Gamut cannot be corrected with LUT. For this you need to do 3x3 matrix multiplication (sufficient when combined with LUT) or 3dLUT
Gamma and gamut, there is nothing else reffered as 'color correction'
This is incorrect. LUT adjustments can achieve two things, and a LUT calibration ideally does both at the same time.

1) They can adjust gamma by applying the same changes to each of the three LUTS, thus changing the luminance function, but preserving the relative differences between each channel, at each of the (256) levels. IIRC, this is called changing the neutral axis.
2) By adjusting each channel independently (remember, LUT adjustments allow you to change 256 x 3 = 768 values), you can change the white point, for each of the 256 luminance levels.

Gamut is a completely different concept from white point. If you want to learn more, read my introduction in the original post in this thread - it goes over these concepts.


The fact that WinDAS asks you for calibration at "multiple IRE's" does not mean it can actually use these information to correct gamma in multiple places but because of limited precision of measurement devices with less light hitting it.
I don't know what this sentence means.

If it was possible to get different gamma just by using WinDAS then SONY would use such functionality and make sRGB mode not suck. Each Trinitron in sRGB mode have very high black level - have you ever wondered why?
sRGB is a strange standard with somewhat ill defined specs. You can learn more about that in Poynton's bible. From what I remember, I think Trinitron sRGB mode tries to emulate certain contrast and gamma functions that assume a particular ambient lighting environment. That aside, to get proper control over gamma, you need more than a few points at which to adjust the value. LUT adjustments (with argyllCMS, for example, allow both white point and luminance tweaking at all 256 levels). WinDAS was not designed for control over gamma. It was designed for control over white point.

To date you provided no good hard data to prove WinDAS can do anything else than set ranges for OSD control.
The difference between you and the rest of us is that we've tried both. You haven't.

And as I've reiterated recently, this is less about tube health, and more about visual performance.

What I find astonishing is that you haven't even tried a WPB. You might even see no difference, but the fact that you haven't even tried speaks volumes.
 

spacediver

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Nothing to say, XoR?

I'm interested to see whether you still believe the phosphor response is what is responsible for CRT gamma, given the evidence I've presented.

I'm also curious to understand why you believe LUTs can only adjust gamma.
 

XoR_

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Nothing to say, XoR?

I'm interested to see whether you still believe the phosphor response is what is responsible for CRT gamma, given the evidence I've presented.

I'm also curious to understand why you believe LUTs can only adjust gamma.
Dude, chill out :confused:

So I was wrong, now what? It doesn't prove you can correct gamma with WinDAS... it at least make it kinda possible so is a good theoretical staring point to even try tinkering with WinDAS.
Thanks for info (y)

As for gamma and gamut being only things correctable... LOL, this was stupid omission on my side :ROFLMAO: (and haven't I already made similar mistake in the past?)
Of course we also correct white point... not with LUT's though, not if you do calibration properly ;)

What I find astonishing is that you haven't even tried a WPB. You might even see no difference, but the fact that you haven't even tried speaks volumes.
What 'volumes'? What are you talking about? :confused:
I will get to it, do not worry. Currently I have my Dell P1110 in closet and FW900 hundreds of kilometers from where I am at :( I do not have proper desk, space to host another monitor. Will need to also prepare XP on laptop. Lot's of effort you see...
 

XoR_

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Why would you need XP?
Does it work on Win10?
I remember needing to have XP (actually used Win2000) last time I had to change G2 with WinDAS

...I get there is some way to do it without XP... hell, who cares, I have laptop and spare HDD so XP it is :)
 

spacediver

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Of course we also correct white point... not with LUT's though, not if you do calibration properly ;)
Agreed that the better the display (and the better the hardware calibration), the less fine tuning will be required by the LUT, but think of a LUT as allowing 256 points of control - you basically get to dial in the white point for each point along the neutral axis. Kinda like how some displays allow for 10 point gamma control, a LUT allows for 256 point gamma control, and 256 point "white point control".


I will get to it, do not worry. Currently I have my Dell P1110 in closet and FW900 hundreds of kilometers from where I am at :( I do not have proper desk, space to host another monitor. Will need to also prepare XP on laptop. Lot's of effort you see...
I hear that - it's been over a year since I've done one on my units. Been cheating and just using the brightness control to improve blacks :p
 

jbltecnicspro

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Does it work on Win10?
I remember needing to have XP (actually used Win2000) last time I had to change G2 with WinDAS

...I get there is some way to do it without XP... hell, who cares, I have laptop and spare HDD so XP it is :)
I still keep my spare XP craptop around just for WinDAS. Because at the end of the day, it's just easier to set up and use.
 

christpunchers

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I'm pulling hair out with HCFR.

Got a new FW900 today, calibrated it. Wanted to check the average gamma and contrast level (I have a i1 Display Pro). Usually it's just a matter of going into HCFR and clicking on grayscale testing, wait a few minutes, and I'll see the average gamma and contrast. But now, with 4 different versions of HCFR, it never shows up. The rest of the stuff shows up fine (Delta E, CDM2, etc). I have no idea what's wrong with my setup. Can anyone help?
 

aeliusg

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I'm pulling hair out with HCFR.

Got a new FW900 today, calibrated it. Wanted to check the average gamma and contrast level (I have a i1 Display Pro). Usually it's just a matter of going into HCFR and clicking on grayscale testing, wait a few minutes, and I'll see the average gamma and contrast. But now, with 4 different versions of HCFR, it never shows up. The rest of the stuff shows up fine (Delta E, CDM2, etc). I have no idea what's wrong with my setup. Can anyone help?
Never used HCFR, but try DisplayCal. Sorry if that's not helpful with your specific issue, but IDK otherwise.
 

brownvim

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When I boot up my FW900 its very green and takes a while (30mins) for the green tint to go away.

It seems like the display is too bright on startup and then settles down to getting decent black levels.

This is with brightness set to 0, if I raise it to 10 the screen gets very green again.

Do I need to use windas to correct this?
 

aeliusg

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When I boot up my FW900 its very green and takes a while (30mins) for the green tint to go away.

It seems like the display is too bright on startup and then settles down to getting decent black levels.

This is with brightness set to 0, if I raise it to 10 the screen gets very green again.

Do I need to use windas to correct this?
No, this is normal for FW900’s from what we can tell. Never had one fresh out of the box, so can’t say what a new tube would do. There is a circuit (Q401) you can disable to get it to start off dark, but you’d have to pop open the case and do some soldering. Will also require recalibrating your gamma.
 

brownvim

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Ok so it’s normal behaviour.

I literally have to have it at 0 brightness to get good black levels, setting it to 5 or 10 just makes the black in an image look green.

I don’t want to risk opening it, the colours look fine to me by eye after 30 mins.

Thanks.
 

jbltecnicspro

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Ok so it’s normal behaviour.

I literally have to have it at 0 brightness to get good black levels, setting it to 5 or 10 just makes the black in an image look green.

I don’t want to risk opening it, the colours look fine to me by eye after 30 mins.

Thanks.
This doesn't sound normal. Old post, so sorry for the bump. My Artisan's black levels are first pretty high when the monitor warms up, but its very neutral gray. Sounds to me like your green's bias is a bit too high. Nothing a white point balance operation won't fix. In the meantime, you could simply do quick bias/gain adjustment. Use the NEC pattern generator and display a full white and adjust your gain so that it's 6500k (x = 0.313, y = 0.329), and then right click on the full white pattern to display the dark grey one (I forget if it's 30 or 20 ire), and adjust your bias so that it's also 6500k (x = 0.313, y=0.329). Then check the grey that's in between the dark and full white to make sure that you're close (delta E < 3.0 is preferable). Then you should be good. Luminance (Y m/2) should be about 95 cd/m2 on the whitest white.
 

brownvim

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This doesn't sound normal. Old post, so sorry for the bump. My Artisan's black levels are first pretty high when the monitor warms up, but its very neutral gray. Sounds to me like your green's bias is a bit too high. Nothing a white point balance operation won't fix. In the meantime, you could simply do quick bias/gain adjustment. Use the NEC pattern generator and display a full white and adjust your gain so that it's 6500k (x = 0.313, y = 0.329), and then right click on the full white pattern to display the dark grey one (I forget if it's 30 or 20 ire), and adjust your bias so that it's also 6500k (x = 0.313, y=0.329). Then check the grey that's in between the dark and full white to make sure that you're close (delta E < 3.0 is preferable). Then you should be good. Luminance (Y m/2) should be about 95 cd/m2 on the whitest white.
Thanks for the reply, the NEC pattern generator looks handy.

I'm assuming I need a coloromiter to check if i'm at 6500k and what delta error i'm at?
 

jbltecnicspro

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Thanks for the reply, the NEC pattern generator looks handy.

I'm assuming I need a coloromiter to check if i'm at 6500k and what delta error i'm at?
Yeah, unfortunately this is one of those things where you cannot eyeball it. Only way I can think of a way to eyeball would be to take a reference that you know is correct and then match to it, but even that's a difficult task to accomplish. DTP-94 is a good meter for these monitors. They shouldn't be expensive either.
 

brownvim

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Hmmm the closest thing I have to reference is a Sony A1 OLED and an iPhone XS.

Not sure how to display 6500k though.

I will look into the X-Rite.
 

jbltecnicspro

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Hmmm the closest thing I have to reference is a Sony A1 OLED and an iPhone XS.

Not sure how to display 6500k though.

I will look into the X-Rite.
Check reviews for iPhone XS. I'm pretty sure it has accurate white point. If you can display a full white image on (that's generated) then lower the brightness to more or less match your FW900, that may work. But I would strongly suggest getting a meter instead. But yeah, it may do in a pinch.

EDIT: Here's Anandtech's review of the phone. Accurate grayscale indeed!

https://www.anandtech.com/show/13392/the-iphone-xs-xs-max-review-unveiling-the-silicon-secrets/8
 

brownvim

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Ok so that’s made a big difference to the Colors I was seeing before, looks a lot more accurate.

I moved the green down from 100 to 82 and also had to adjust the blue a little on both the gain and bias.

It still boots up green though, I will try and post a video of what happens later.
 
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brownvim

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Here’s a link to a video of what happens when I turn the monitor on:


Camera doesn’t capture it too well as there’s a lot of flicker but it’s green most of the time like the picture attached.

At 1:17 the flickering stops and a I get a solid green tinted picture.

This green tint lasts for upto 30mins, gradually fading to get back to normal black levels.
 

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aeliusg

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Wow, that’s pretty bad. I’d thought you meant a greenish tinge, but that’s obviously bad components somewhere in there. You will probably need to replace some capacitors at the least.
 

jbltecnicspro

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Wow, that’s pretty bad. I’d thought you meant a greenish tinge, but that’s obviously bad components somewhere in there. You will probably need to replace some capacitors at the least.
Yeah, not quite what I was expecting at all. That's pretty bad. I can see the retrace lines and everything.
 

spacediver

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Try turning the monitor off when it starts acting up when you turn it on. Leave it off for a few seconds, then turn back on. Repeat 2 to 3 times. Does that prevent the retrace lines?
 

brownvim

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Try turning the monitor off when it starts acting up when you turn it on. Leave it off for a few seconds, then turn back on. Repeat 2 to 3 times. Does that prevent the retrace lines?
It actually turns itself off if it’s getting a signal as it gets brighter and brighter that’s why in the video you see me change the source.

I always get them lines on a cold boot up whether I keep turning it off and on or not. So no it doesn’t prevent the retrace lines.

When it’s warm I can turn it on and off and black levels are fine and no crazy green hulk mode.

I read somewhere that there’s a brightness bias circuit in the monitor that tries to keep the monitor bright on boot then fade as it warms up to keep brightness balanced? But this circuit seems messed up on mine maybe?
 

spacediver

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The ABL (automatic brightness limiter) is what's causing it to turn off. That's why I recommend manually turning it off before the brightness threshold is reached and it automatically turns off. That's what I do on my tube when it's cold and i turn it on for first time in a while.
 

brownvim

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Oh I see, ye I would have to turn it on and off around 5-6 times until I get a picture.
 

spacediver

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Oh I see, ye I would have to turn it on and off around 5-6 times until I get a picture.
yep, probably best to do this to avoid risking damage to tube. If I figure out how to solve the issue, I'll let you know (once I get around to trying to restore properly!)
 

spacediver

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also, I think a WPB might help resolve this issue (not sure though, will also let you know when I do my next one (sorely overdue!)
 

Sketchus

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Hi folks,

Really interesting thread. I've spent a good deal of time looking at the info as I have a P1130. The black levels were quite raised so initially I just did a G2 tweak which helped a lot.

Just want to clarify something though.

I use the monitor with my Win98 retro PC, which is fine, as if I calibrate it for deep blacks, I can adjust the gamma curve in the nvidia control panel. However I also use an OSSC to play console games in 480p. The gamma selection is not so easy in that.

From what I understand if I want correct gamma levels on devices that don't have adjustable gamma, it's just going to be a case of upping the brightness? Basically a toss up between deep blacks and correct gamma.

Not a problem if that is the case, just want to make sure I'm not missing something.
 

jbltecnicspro

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Hi folks,

Really interesting thread. I've spent a good deal of time looking at the info as I have a P1130. The black levels were quite raised so initially I just did a G2 tweak which helped a lot.

Just want to clarify something though.

I use the monitor with my Win98 retro PC, which is fine, as if I calibrate it for deep blacks, I can adjust the gamma curve in the nvidia control panel. However I also use an OSSC to play console games in 480p. The gamma selection is not so easy in that.

From what I understand if I want correct gamma levels on devices that don't have adjustable gamma, it's just going to be a case of upping the brightness? Basically a toss up between deep blacks and correct gamma.

Not a problem if that is the case, just want to make sure I'm not missing something.
You're correct. You can usually compromise with a CRT by setting your brightness so that your gamma is 2.3 - 2.4. If you set it to 2.2, your blacks will be elevated.
 

Sketchus

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Thanks for that, that's good to know. Slightly raised blacks in some cases shouldn't be too much of an issue, as soon as I can stop fiddling around with the settings that is.
 

Sketchus

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Can anyone comment on what sort of warm up time is expected for the colours to settle? My Dell P1130 takes 20-30 minutes I'd say for the blacks to settle to where they should be.
 

spacediver

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I like to give it a full hour of warmup before doing a WPB. But for general use, yea 20-30 min is about right for when they settle.
 

Sketchus

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Good to know, I'm glad that's the case.

If you happen to know as well, what's the best setting to bump up the max available contrast? I have C_MAX_B_CENT which seems to affect it, but that resets if I switch the monitor off for a while. There is also the C_MAX_B_MAX setting.

I don't want to increase it massively, just bring the level up a little.

EDIT:

Looks like I've been changing the global value, which resets. Is there a value for each colour temperature?

Double EDIT:

I figured it I think. You have to edit contrast under the specific colour profile in Windas, and also bump it up the C_MAX_B_CENT setting, which is specific to each profile.

My only question is now, what does C_MAX_B_MAX actually do?
 
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spacediver

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I've never edited those settings directly. WinDAS does it automatically if you follow the procedure correctly.
 

Sketchus

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I've never edited those settings directly. WinDAS does it automatically if you follow the procedure correctly.

Ah yes, I have done it that way as well, but just wanted to bump up the contrast ever so slightly without reconfiguring the entire thing again.

The only issue I have now is that some modes my OSSC outputs don't fill the screen, horizontally, but I don't know if that's the monitor or the OSSC.
 
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