Contrasting Settings - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #1 of 56 Old 02-02-2011, 08:01 PM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
This is yet another "Where to set contrast thread" (sorry).

I'm quite confused about the white level and that's sad because I've been studying calibration (as an enthusiast) for about 5 years now and this is the one thing that's haunted me this whole time. Any further clarification would be appreciated.

It seems that some say something like "maximize contrast ratio by jacking up your white level control so long as it doesn't cause clipping, geometry distortion (crt), color-shifting, or eye fatigue/strain"

and another that states something like "keep contrast (white level) LOW; very dim. Turn contrast all the way down and start slowly bringing it up to the point where white JUST becomes white, etc.".

My issue is that I have tried MANY MANY times, both ways (and many others) of setting contrast on my displays.

I find that the "pop" of cranking the white level (without the previously mentioned issues) is very exciting. I worry however that this might be something like an "SRS WOW effect" in WMP or something equally cheesy.

I also find that I can get my whites to appear to be white to me at a VERY low level for a direct view display (crt and lcds in my cases); namely hovering around 5ftL or less of light output (measured with an i1d2). This is dimmer than a lot of projectors and I happen to think it too looks absolutely fantastic (given the corresponding room environment).

Now my problem is that it upsets me that there's exact (or at least as I see them "exact") measurements and points for every other adjustment with displays (black levels, color gamut, greyscale, rec601 and 709, etc.). However with white level, all I ever seem to come across is a kind of "whateva floats ya boat, yo." and that bothers me.

I did see somewhere that THX calibrate their post production monitors to 35ftL of light output, but that's about all I could find.

I would like to match the standards of the professional environment in which the content we view is created, but I have this icky feeling that it's the same situation in studios as it is in home environments... a "whateva, foo!"-type mentality to this setting.

I know I'm probably exaggerating, but I'm really hoping that someone can come along and shed some light (no pun intended) on this situation before I end up creating a thread asking what others calibrate their peak whites to (ick!).

Oh! One last thing: I once was in a thread and someone (can't remember) briefly touched on that the contrast measurement is directly proportional to the field of view of the viewer. I tried a couple times to get them to elaborate or provide some data or numbers to no avail. This concept to me sounds very rational and if anyone has any input, I'd LOVE to hear it.

Thanks in advance!
-Brian

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
Sponsored Links
Advertisement
 
post #2 of 56 Old 02-03-2011, 02:54 AM
Advanced Member
 
Light Illusion's Avatar
 
Join Date: Aug 2010
Posts: 522
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 211
Professional monitors for the post industry used to be set to 35 foot lamberts (120cd/m2) in the days of CRTs based on the SMPTE spec.

However, most post houses reduced this to below 30FtL to save tube life.

Remember the mastering in a port house is where the film/program was made to look correct - on the displays they uses that are professionally set-up.

The ideal home environment is to match this as accurately as possible.

With LCD displays (and Plasmas) this level is not realistic any more, and most set the peak white to approx 23FtL.

Cinema levels are 16FtL open gate, which equates to approx 14FtL with D-min (transparent film in the gate).

But, a cinema environment is very different to a tv in the home lounge, so to make to two 'feel' the same requires different settings.

Also, cinema white is approx D55, while a home tv is D65. This also changes what the contast 'feels' like.

Hope this helps.

Steve Shaw
LIGHT ILLUSION

Light Illusion is offline  
post #3 of 56 Old 02-03-2011, 06:31 AM
Member
 
thewizardhunter's Avatar
 
Join Date: Jan 2010
Posts: 38
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Hi Brian,

Not sure if this would help you but I follow the advice/Rule...

No Clipping
No Discoloration
No Eye Fatigue

My viewing enviroment is a dim room and the 100IRE test patern on my calibrated LCD HDTV measures 32FtL. In my oppinion as long as you follow those three basic rules/guides for calibrating white level then you shouldn't need to worry.

Those people with sensitive eyes that have a similar viewing enviroment to mine may end up with 27Ftl after white level calibration on their LCD displays.

I've tested with several Ftl for white level and obviously the higher you can achieve without clipping and discoloration the more the picture "Pops".

-----------------
TheWizardHunter
-----------------
thewizardhunter is offline  
post #4 of 56 Old 02-03-2011, 06:40 AM
AVS Special Member
 
Michael TLV's Avatar
 
Join Date: Feb 2000
Location: THX/ISF Calibrationist/Instructor, Calgary, AB, Canada
Posts: 6,723
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 114
Greetings

Until eye fatigue levels become the same for everyone ... then contrast will always have this latitude.

Unless of course you think that there is one all powerful number for eye fatigue considerations that applies to the whole human race?

What fatigues me may not fatigue you. What fatigues you today may not fatigue you tomorrow. How do you reconcile that?

Fatigue is a function of at least the 4 following items ...

Physical states
Mental states
Program material
Viewing environment

A display that gives you a headache to watch is not much of a display at all.

Regards

Michael Chen @ The Laser Video Experience
ISF/THX/TLV Video Instructor
The Video Calibration Education Hub - www.TLVEXP.com

Michael TLV is offline  
post #5 of 56 Old 02-03-2011, 06:47 AM
Member
 
thewizardhunter's Avatar
 
Join Date: Jan 2010
Posts: 38
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
As usual Michael, your input is excellent :-)

-----------------
TheWizardHunter
-----------------
thewizardhunter is offline  
post #6 of 56 Old 02-03-2011, 06:48 AM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Light Illusion View Post

Remember the mastering in a port house is where the film/program was made to look correct - on the displays they uses that are professionally set-up.

The ideal home environment is to match this as accurately as possible.

This is what I was trying to get at in particular. Since the film was created and mastered in a post house to look correct to the person or people mastering it in their particular environment, wouldn't it be reasonable to assume that to get the most faithful reproduction of the material, one would need to recreate the same environment that it was mastered in?

I'm not saying going out and buying 100s of thousands of dollars worth of equipment, etc. but I am saying that it WOULD be the "ideal" environment to get the most faithful recreation, correct?

If this is the case, then at least it would provide a baseline of deviation. One could then know that if they change something from the "spec" of a mastering house, then they could at least understand what compromises they are making.

However when you don't know what the original environment was, then what are you deviating from? How do you know what compromises you are making?

I hope this makes sense.

Quote:
Originally Posted by Light Illusion View Post

But, a cinema environment is very different to a tv in the home lounge, so to make to two 'feel' the same requires different settings.

Also, cinema white is approx D55, while a home tv is D65. This also changes what the contast 'feels' like.

This further elaborates on my original point. Unless for some reason I am unable to understand, a home environment COULD be 100% accurate to a mastering environment, and thus have the same "feel" and be calibrated to D55 if what you say is true about that (which the thought of scares the crap out of me). :P

I just simply want to know what the baseline is (which I have a feeling that there isn't one

I want to know what it is I am deviating from... The starting point, so that I can know what my "compromises" entail.

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #7 of 56 Old 02-03-2011, 06:58 AM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Michael TLV View Post

Greetings

Until eye fatigue levels become the same for everyone ... then contrast will always have this latitude.

Unless of course you think that there is one all powerful number for eye fatigue considerations that applies to the whole human race?

What fatigues me may not fatigue you. What fatigues you today may not fatigue you tomorrow. How do you reconcile that?

Fatigue is a function of at least the 4 following items ...

Physical states
Mental states
Program material
Viewing environment

A display that gives you a headache to watch is not much of a display at all.

Regards

Quote:
Originally Posted by thewizardhunter View Post

As usual Michael, your input is excellent :-)

I too always look forward to hearing from Mr. Chen (I'm also always scared of posting here because I worry how he'll make me feel really stupid. Haha).

I understand perfectly what you are saying and I think exactly the same thing and if you can elaborate on just a couple more points, I'll keep my noob mouth shut. lol

1. It doesn't matter how white white is, as long as it meets the clipping, color-shifting, and eye fatigue values you tout everywhere, because white is white is white... correct?

2. If that's the case (which I DO think it is...) then would having a higher contrast ratio in the same display "expand" the range physically? Could it add in MORE grey "steps"?

In other words, in the reverse... Could shrinking the contrast ratio (such as having a VERY low white level, actually clip out grey steps and levels OR would they simply become smaller but still there?

I personally think they would become smaller but still there with CRTs for sure... but digital displays... well I just don't know.

Is it better to maximize your contrast ratio by cranking up the white level to meet the aforementioned criteria or is having the white level a LOT lower than the criteria just as acceptable?

Please don't eat me. :P

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #8 of 56 Old 02-03-2011, 07:25 AM
Member
 
thewizardhunter's Avatar
 
Join Date: Jan 2010
Posts: 38
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Greetings again Kamui,

Regarding your first point... Think you may be about to open a can of worms here but that's all good :-)

"1. It doesn't matter how white white is, as long as it meets the clipping, color-shifting, and eye fatigue values you tout everywhere, because white is white is white... correct?"

My Answer, White may appear to be white but the white you want for your home movie viewing should be D65 White.

In other words on uncalibrated displays the white you see may have too much blue, red or green but will look white to you and everybody you ask "What colour is that 100IRE patern"?.

I'll leave the rest for Michael's input.

Good valid questions by the way. The idea of this forum is to share ideas and information. So don't be afraid to ask or answer. There will always be someone lurking around to update your knowledge if it's not quite acurate. Hence "Forum" :-)

-----------------
TheWizardHunter
-----------------
thewizardhunter is offline  
post #9 of 56 Old 02-03-2011, 07:31 AM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by thewizardhunter View Post

Greetings again Kamui,

Regarding your first point... Think you may be about to open a can of worms here but that's all good :-)

"1. It doesn't matter how white white is, as long as it meets the clipping, color-shifting, and eye fatigue values you tout everywhere, because white is white is white... correct?"

My Answer, White may appear to be white but the white you want for your home movie viewing should be D65 White.

In other words on uncalibrated displays the white you see may have too much blue, red or green but will look white to you and everybody you ask "What colour is that 100IRE patern"?.

I'll leave the rest for Michael's input.

Good valid questions by the way. The idea of this forum is to share ideas and information. So don't be afraid to ask or answer. There will always be someone lurking around to update your knowledge if it's not quite acurate. Hence "Forum" :-)

I'm sorry I wasn't clear enough about what I said there. I DO understand about calibrating to D65 (because it's a standard, unlike a peak light output).

I didn't mean the color of white... I meant the luminance.

Thank you though, for sure!

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #10 of 56 Old 02-03-2011, 07:47 AM
AVS Special Member
 
turbe's Avatar
 
Join Date: Feb 2001
Location: Lake Tahoe, NV
Posts: 4,424
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 84
maximized doesn't have to mean you keep your Display's Contrast at that level. you want to find what the display is capable of for your environment(s), you may want to reduce the setting. Also, what do you find acceptable for WTW if it's clipping on your display?

I personally find 30-32fL right for my plasma in my environment with ambient light control (much less for the projector). That's not maximized on the Plasma (it is close on the projector). I'm not sure maximize is the right term.

Unfortunately, for some past models, a display's maximized setting is not enough even for reference viewing. On others, reducing Contrast (even a little) from the maximized setting may cause issues (like #2 in post #3 above).

Need to find a Professional Calibrator? Click Here to PM me with your Display & City

Calibrator List - Pioneer ISFccc Interface

Calibration Reports - Pioneer

 

ControlCAL™
Designed by Calibrators for Calibrators™

No need to fumble through the Display's Menu with its Remote Control™

turbe is online now  
post #11 of 56 Old 02-03-2011, 08:23 AM
AVS Special Member
 
Kelvin1965S's Avatar
 
Join Date: Apr 2007
Location: Berkshire, UK
Posts: 3,230
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Liked: 31
I just wanted to add that I feel that using the contrast control to set the fL of a display seems a bit like controling the speed of your car by using the brakes at the same time as the throttle: If there is a control in the display such as backlight (for LCD), cell level/brightness (Plasma) or iris/lamp brightness (projector) then IMHO these should be used where possible to tune the fL. You would then set the contrast control to ensure that whites are not being clipped or tinted using a test pattern and meter.

In my case I prefer to set contrast to allow upto 240 to be seen (rather than hard clipping at 235), though I know some prefer to see all the way upto 254. I then adjust the backlight on my TV or the iris on my projector to achieve the fL I want. This way I'm not throwing away any contrast (especially important with the projector).

Zooming: Been there, done that, bought the lens...
Kelvin1965S is offline  
post #12 of 56 Old 02-03-2011, 08:35 AM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Alright... So what I'm getting (that I've always got) is that peak luminance is determined by the end user and it's adjustable to whatever level suits your tastes and environments. I understand that and it's fine... I suppose I could live with that.

In response however to my previous question about expanding and contracting the contrast ratio... Does doing that expand or contract the dynamic range via clipping out "steps of grey"?

I honestly don't think it would with an analog display such as a CRT, but with digitals, I could see how it might.

The reason for this is that I wonder if it's anything like audio dynamic range, where when you have a very small dynamic range, things get compressed and stuff clips out at the high and low ends (in example: car door slams sound the same loudness as 10 megaton explosions).

I don't think it is though because it's not like with a compressed contrast ratio, fireflies glow as brightly as a flood light.

I just want to know if there is actual physical losses (aka "clipping") of "grey steps" when you reduce your contrast ratio... or does it simply get rid of that "neat-o" effect of a bright "pop" in the image?

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #13 of 56 Old 02-03-2011, 11:32 AM
AVS Special Member
 
Michael TLV's Avatar
 
Join Date: Feb 2000
Location: THX/ISF Calibrationist/Instructor, Calgary, AB, Canada
Posts: 6,723
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 114
Greetings
Some of this comes down to bit depth and some tvs will do it better than others
Regards

Michael Chen @ The Laser Video Experience
ISF/THX/TLV Video Instructor
The Video Calibration Education Hub - www.TLVEXP.com

Michael TLV is offline  
post #14 of 56 Old 02-03-2011, 06:42 PM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by kamui View Post

...before I end up creating a thread asking what others calibrate their peak whites to.

So fellas... what ftL do you set YOUR peak whites to? Haha

I guess I give up on this question of proper white level. Thanks for all your input gentleman.

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #15 of 56 Old 02-03-2011, 08:55 PM
Advanced Member
 
Light Illusion's Avatar
 
Join Date: Aug 2010
Posts: 522
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 211
I direct you all back to my first reply.

There is only one 'correct' setup - and that is to match as closely as possible the display and environment on which the 'film' was originally mastered.

There is no other 'correct' set-up.

(I do this for a living - so do know what I am talking about - check the Light Illusion website for more info)

All material to be viewed at home is mastered using Rec709 colourspace, with a peak brightness level of approx 23FtL, and D65 illuminant. As I said before SMPT spec states 35FtL but that is not viable with today's display systems, and in reality was never used as it is too high.

What you have to remember is that home use material (DVDs, Blue
Ray, etc) are mastered for home tv viewing, not home cinemas.

So, as a result, setting home cinema to 'film theatre' specifications (14FtL and a D55 Illuminant) will be wrong for the footage you are viewing.

So you have to compromise when using a home cinema rather than a tv.

I hope this makes sense.

Steve Shaw
LIGHT ILLUSION

Light Illusion is offline  
post #16 of 56 Old 02-03-2011, 09:08 PM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Light Illusion View Post

There is only one 'correct' setup - and that is to match as closely as possible the display and environment on which the 'film' was originally mastered.

There is no other 'correct' set-up.

THIS... This is what I want(ed). I want to calibrate my displays as closely as possible to the mastering environment.

I certainly hope you didn't think I was implying that I want to match the "theater megaplex" environment as I believe that to look and "feel" like complete crap. I detest theaters; both visually and sonically.

I had almost this exact same discussion about how to set up 5.1 speakers in a home environment and I found out through (Ethan Winer, I believe) that mastering studios (where the music is actually MADE) set them up in a very specific manner MUCH different than a theater or other environment.

I set my speakers up to match the mastering studio as closely as I could manage and it made the best improvement ever to my sound. I love it.

I want the same for my video (if possible).

I think I am confusing what you're saying though.

Could you make it real basic for someone like me? lol

For example:

---
Home Environment: D65, rec709, 23ftL, etc.

Mastering House (where the film was created!): D55, rec709, 35ftL, etc.
---

I want to match the mastering house if possible as I believe that setting my display to match that would give me the same view that the person who MADE the content had.

Am I missing something completely?

Sorry I might have glazed over your first response too.

Thanks again!

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #17 of 56 Old 02-03-2011, 09:24 PM
AVS Special Member
 
Michael TLV's Avatar
 
Join Date: Feb 2000
Location: THX/ISF Calibrationist/Instructor, Calgary, AB, Canada
Posts: 6,723
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 114
Greetings

You'd better change the color of the walls in the room and the lighting as well to match this.

Regards

Michael Chen @ The Laser Video Experience
ISF/THX/TLV Video Instructor
The Video Calibration Education Hub - www.TLVEXP.com

Michael TLV is offline  
post #18 of 56 Old 02-04-2011, 03:11 AM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by Michael TLV View Post

Greetings

You'd better change the color of the walls in the room and the lighting as well to match this.

Regards

Haha, I have actually.

I've painted my walls a neutral grey tone and have an IdealLume bias light.

Granted, I'm speaking of D65 and I have zero plans of D55 calibration, but I'm willing to listen to what Light Illusion says, as long as I can confirm any of it.

I just simply can't comprehend why in this one area there wouldn't be a standard. I know why there are all sorts of deviations (as with everything), but in order to deviate, one would (I think) have to know what it is they're deviating from.

I can't see how a picture that produces a white luminance of say 3ftL is the same image as one that produces a white luminance of say 60ftL.

They look nothing similar to me. I get an extremely different feel when I watch one vs the other but neither give me eye strain or fatigue and I enjoy both equally but for very different reasons.

I simply want to know why you would choose one over the other and that if you (Michael TLV [because I trust you]) say it really IS just preference, I will just shut up and trust you (albeit it stay very confused without a better explanation).

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #19 of 56 Old 02-04-2011, 07:45 AM
AVS Special Member
 
sotti's Avatar
 
Join Date: Aug 2004
Location: Seattle, WA
Posts: 6,585
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Liked: 164
Quote:
Originally Posted by kamui View Post

I simply want to know why you would choose one over the other and that if you (Michael TLV [because I trust you]) say it really IS just preference, I will just shut up and trust you (albeit it stay very confused without a better explanation).

Post production houses that master content for home (Blu-Ray, HD video for premium channels, ect) use D65 and rec.709

The reason white level fluctuates and is somewhat subjective is because the value is highly dependent on environmental factors. If you have dark gray walls, an ideal lume bias light and total light control then the 15fl range may be very appropriate for you viewing.

But if you calibrate my living room with a window opposite the TV, absolutely no light control, ect... 15fl will look way too dim, 30-35fl is much more appropriate.

Your eye is extremely adaptive to it's environment, so you calibration needs to be sensitive to it's environment.

Joel Barsotti
SpectraCal
CalMAN Lead Developer
sotti is offline  
post #20 of 56 Old 02-04-2011, 08:13 AM
AVS Special Member
 
buzzard767's Avatar
 
Join Date: Dec 2005
Location: Naples, FL & Wausau, WI
Posts: 3,552
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Liked: 327
Right on, sotti. My viewing room is totally light controlled with what could be best described as medium brown flat paint. I use one Ideal Lume bias light. My DLP only puts out 20 fL calibrated but any more would be too much.
LL

Buzz
THX Certified Video Calibrator

 

buzzard767 is offline  
post #21 of 56 Old 02-04-2011, 08:24 AM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by sotti View Post

Post production houses that master content for home (Blu-Ray, HD video for premium channels, ect) use D65 and rec.709

This one I understand and "know".

Quote:
Originally Posted by sotti View Post

The reason white level fluctuates and is somewhat subjective is because the value is highly dependent on environmental factors. If you have dark gray walls, an ideal lume bias light and total light control then the 15fl range may be very appropriate for you viewing.

Agreed. I also understand this concept as it makes complete sense.

Quote:
Originally Posted by sotti View Post

But if you calibrate my living room with a window opposite the TV, absolutely no light control, ect... 15fl will look way too dim, 30-35fl is much more appropriate.

Your eye is extremely adaptive to it's environment, so you calibration needs to be sensitive to it's environment.

If there's no mathematical way to calibrate for an environment (such as ambient light, natural light, field of view, etc.), then it would seem logical that it's practically subjective to the viewer how bright they want their white levels to be.

In other words, in my case I can calibrate to say 15ftL in my darkened environment OR I could CHOOSE to calibrate to say 80ftL (as long as it's not clipping, color-shifting, or fatiguing), correct?

If your answer is "yes, that's correct", then fine... I will bow out and shut up about this question I'm sure you're all tired of hearing :P

If however it's NOT the case, then I'm utterly confused.

Either way, it still doesn't make sense to me.

I really want to give you an example.

For instance I just finished playing all the way through Dead Space on my 360 with a ftL reading from my i1D2 of about 15ftL peak white.

The game looked amazing (due to other calibrations as well) and it was dark and scary but anytime there was white, it was definitely white (not grey) to me.

Now that I've beaten it, I've calibrated my TV again for about 50ftL peak white this time.

Now that I'm running through the game again, I can see a LOT more detail and a lot of artifacts that are natural to the limitations of the 360 and it looks fantastic detail-wise. However the "dark and scary" feelings have been VASTLY diminished.

Personally I think it's a really good thing that it's brighter because I'm getting more detail and the reason it's not the same feeling is because I'm seeing more than I should... As though my display is TOO good for the game (if that makes any sense).

Is this difference really negligible? Can the two completely different light outputs and different "feel" and "look" to everything I watch not matter?

I really hope I don't sound too much like an idiot, but if you want, I could try to take a few pictures of the differences I'm referring to of the different calibrated settings.

What am I missing here?

Thanks so much so far!

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #22 of 56 Old 02-04-2011, 08:58 AM
AVS Special Member
 
sotti's Avatar
 
Join Date: Aug 2004
Location: Seattle, WA
Posts: 6,585
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Liked: 164
Quote:
Originally Posted by kamui View Post

This one I understand and "know".



Agreed. I also understand this concept as it makes complete sense.



If there's no mathematical way to calibrate for an environment (such as ambient light, natural light, field of view, etc.), then it would seem logical that it's practically subjective to the viewer how bright they want their white levels to be.

In other words, in my case I can calibrate to say 15ftL in my darkened environment OR I could CHOOSE to calibrate to say 80ftL (as long as it's not clipping, color-shifting, or fatiguing), correct?

If your answer is "yes, that's correct", then fine... I will bow out and shut up about this question I'm sure you're all tired of hearing :P

If however it's NOT the case, then I'm utterly confused.

Either way, it still doesn't make sense to me.

What am I missing here?


People are working on mathematical models to help reproduce images from one viewing environment to another.

What you're missing is the gamma curve that describes how gray transitions from black to white.

Should those shadows in dead space be perceptible? If they should, then you should have an appropriate gamma curve that reveals them at both 15fl and 50fl. Conversely if the detail is suppose to be obscured in shadow, the gamma curve could provide the same effect regardless of white level.

The formula that takes environmental light, peak white and produces the appropriate compound gamma curve that would represent the viewing experience in the reference mastering environment isn't available yet, but I believe there are people in the industry working on such models.

Joel Barsotti
SpectraCal
CalMAN Lead Developer
sotti is offline  
post #23 of 56 Old 02-04-2011, 09:15 AM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by sotti View Post

People are working on mathematical models to help reproduce images from one viewing environment to another.

What you're missing is the gamma curve that describes how gray transitions from black to white.

Should those shadows in dead space be perceptible? If they should, then you should have an appropriate gamma curve that reveals them at both 15fl and 50fl. Conversely if the detail is suppose to be obscured in shadow, the gamma curve could provide the same effect regardless of white level.

The formula that takes environmental light, peak white and produces the appropriate compound gamma curve that would represent the viewing experience in the reference mastering environment isn't available yet, but I believe there are people in the industry working on such models.

I do indeed believe that's the piece I was missing *ashamed*

I am waiting on my iScan Duo to arrive so that I can fully adjust my gamma curve because it has been giving me some problems.

So just to make sure I understand: If I have correct gamma for both low and high light outputs, the same look and "feel" will be present with both settings?

Having a dim image vs a bright one won't make a difference because I'm only talking about the peak whites, whereas gamma refers to the function of how fast white comes out of black and therefore wouldn't affect black or white and only the curve or "greys".

Although it's still difficult for me to believe that an image that is so dim vs one that is super bright could look the same, but considering gamma (and how mine is out of whack), I could see how that might be possible.

I suppose I'll just have to wait until I receive my iScan and then if I still feel the same, maybe I'll post here again.

Sorry for asking such basic questions. It must get tiring hearing people try to argue with something that must seem so obvious to more skilled calibrators and enthusiasts. :P

Thanks again!

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #24 of 56 Old 02-04-2011, 09:40 AM
AVS Special Member
 
sotti's Avatar
 
Join Date: Aug 2004
Location: Seattle, WA
Posts: 6,585
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Liked: 164
Well obviously in the same room with the same ambient light, a dim set vs a bright set will never look the same.

what we're looking for is in a bright room with a 65fl display getting the same look and feel as in a dim room with a 15fl display.

Their isn't currently a formula I could point you to that would allow you to describe how to do that, but people are working on such formulas.

To simplify the rules of thumb are:
if the ambient light is higher, your gamma target should be lower.
if the screen is brighter in the same ambient light the gamma should be a little lower.
And then the opposite of both of these are true.

For 15fl in a pitch black room they say a gamma of around 2.4 may be appropriate.

For a display with 65fl in a bright room you may actually want to run a gamma around 2.1 or even 2.0.

Gamma can run anywhere from as low as 1.9 to as high as 2.5 and still look fairly correct given the correct viewing environment.

The real key is that you probably don't want a constant gamma you probably want your gamma a little lower as your ramp out of black.

Joel Barsotti
SpectraCal
CalMAN Lead Developer
sotti is offline  
post #25 of 56 Old 02-04-2011, 10:08 AM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by sotti View Post

Well obviously in the same room with the same ambient light, a dim set vs a bright set will never look the same.

what we're looking for is in a bright room with a 65fl display getting the same look and feel as in a dim room with a 15fl display.

Their isn't currently a formula I could point you to that would allow you to describe how to do that, but people are working on such formulas.

To simplify the rules of thumb are:
if the ambient light is higher, your gamma target should be lower.
if the screen is brighter in the same ambient light the gamma should be a little lower.
And then the opposite of both of these are true.

For 15fl in a pitch black room they say a gamma of around 2.4 may be appropriate.

For a display with 65fl in a bright room you may actually want to run a gamma around 2.1 or even 2.0.

Gamma can run anywhere from as low as 1.9 to as high as 2.5 and still look fairly correct given the correct viewing environment.

The real key is that you probably don't want a constant gamma you probably want your gamma a little lower as your ramp out of black.

I think this answered all of my questions in one fell swoop actually.

It seems gamma is the biggest missing component that's had me all messed up.

The fact that there really isn't a formula (yet) for determining the levels based on room conditions clears up the rest of my concerns.

Thanks Sotti and everyone else who responded here!

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
post #26 of 56 Old 02-04-2011, 07:22 PM
Advanced Member
 
Light Illusion's Avatar
 
Join Date: Aug 2010
Posts: 522
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 211
Gamma should never be changed - that will totally invalidate the original look of the image.

Again, Rec709 is your target, and that specifies 2.2. sRGB has the same colour primaries of Rec709, but a gamma of 1.956.

Changing overall peak brightness is ok - to an extent, but it is far better - and really the only way to acheive accurate calibration - to adjust the viewing environment!

As for my comment on D65/D55 - what I was getting at is that an original film (on film, not D-Cinema) is D55. When the film is re-mastered for home TV the re-grading takes htis inot account so on your D65 TV the image looks the same (similar) the the D55 image at the cinema. You should be calibration to D65.

What I don't get is why no one seem to be doign real calibration vai 3D LUTs?

I have posted this question as a new thread, but no comments. With a HDlink Pro box you could acheive near perfect calibration - you may need additional signal format convertes, but the cost of such boxes is getting a lot cheaper. Things lke iscan duo are toys by comparrision.

Hope this stuff helps. It's kust that to me calibration is a simple process - match what the post house mastered to - including an approximation of their environment. A grading room for TV images is deliberately made to be 'close' to a home environment, but fairly neutral in colours. Ambiant lighting is again like at home.

Cinema grading (DI - Digital Intermediate, which what I do) is different - totally black environment with non-reflective material on the walls.

Steve Shaw
LIGHT ILLUSION

Light Illusion is offline  
post #27 of 56 Old 02-04-2011, 07:34 PM
Advanced Member
 
Light Illusion's Avatar
 
Join Date: Aug 2010
Posts: 522
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Liked: 211
Oh, and bit-depth has no bearing on this at all.

You can have a high contrast display, with perfect white calibration, with just 2 bits.
But you will have no detail/color inbetween black and white - one bit will represent black, the other white (that is a simple approx to the reality, but you get what I am saying).

Bit depth only effects the level of detail in the image - too few bits and the image will look like it is 'posterized' or show 'banding. But as your source will be a compressed image most of the artefacts you see will be from that.

Make sense?

The images I work with are 2K min (4K often) so 12MB per frame at 2K, 48MB at 4K, and are the best you can get. But that takes about 3TB of storage at 2K for a normal feature film at 2K - but, boy are the images great

This is a shot of the latest DI room I have built for a customer: http://www.lightillusion.com/home.htm

It is interesting that the requirements and capabilities of home set-ups is getting closer to the professional ones!

Steve Shaw
LIGHT ILLUSION

Light Illusion is offline  
post #28 of 56 Old 02-04-2011, 08:29 PM
AVS Addicted Member
 
D-Nice's Avatar
 
Join Date: Dec 2004
Location: Columbia, SC
Posts: 14,934
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Liked: 184
Quote:
Originally Posted by Light Illusion View Post

Again, Rec709 is your target, and that specifies 2.2. sRGB has the same colour primaries of Rec709, but a gamma of 1.956.

Are you implying that a gamma of 2.2 is the standard for rec709? If so, that is incorrect. I would love to see official documentations that state 2.2 is the standard. Last I heard the standard is still being debated with 2.2 being one canidate (backed by Sony) and 2.35 being the other.i
D-Nice is offline  
post #29 of 56 Old 02-04-2011, 08:52 PM
AVS Special Member
 
sotti's Avatar
 
Join Date: Aug 2004
Location: Seattle, WA
Posts: 6,585
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 12 Post(s)
Liked: 164
Quote:
Originally Posted by Light Illusion View Post

Gamma should never be changed - that will totally invalidate the original look of the image.

Again, Rec709 is your target, and that specifies 2.2. sRGB has the same colour primaries of Rec709, but a gamma of 1.956.

sRGB most certainly is not a gamma of 1.956, perhaps you should read the spec again.
http://www.color.org/chardata/rgb/srgb.pdf

Also rec.709 has an encoding formula, but not one for viewing. Most people suggest an end to end gamma of 1.1 to 1.2
http://www.poynton.com/PDFs/GammaFAQ.pdf

You'll notice that sRGB fully dictates the viewing environment, which is how they can set the gamma. The spec notes luminance for the display, ambient luminance and viewing surround.

Joel Barsotti
SpectraCal
CalMAN Lead Developer
sotti is offline  
post #30 of 56 Old 02-04-2011, 08:56 PM - Thread Starter
Senior Member
 
kamui's Avatar
 
Join Date: Mar 2005
Location: Coudersport, PA
Posts: 262
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 11
Quote:
Originally Posted by sotti View Post

sRGB most certainly is not a gamma of 1.956, perhaps you should read the spec again.
http://www.color.org/chardata/rgb/srgb.pdf

Also rec.709 has an encoding formula, but not one for viewing. Most people suggest an end to end gamma of 1.1 to 1.2
http://www.poynton.com/PDFs/GammaFAQ.pdf

I think "Light Illusion" is from the UK... Does that have any bearing on the specs? Maybe it is 1.956 across the pond?

sspears:
(Rules? Rules? In Television???? ÂThow shalt not oversaturateth red. ÂRGB shall be thy rod and thy staff; there shall be no other color space before thee.Â)
kamui is offline  
Reply Display Calibration

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off