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post #91 of 484 Old 04-13-2010, 02:12 PM - Thread Starter
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I'm sorry I started this ridiculous thread. And the worst part is I still don't know how to find the proper contrast setting.
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post #92 of 484 Old 04-13-2010, 02:22 PM
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Originally Posted by Jim McC View Post

I'm sorry I started this ridiculous thread. And the worst part is I still don't know how to find the proper contrast setting.

THX says

1) NO CLIPPING!
2) No discoloration
3) No eye fatigue.


They don't even list maximizing brightness or comprimise on any of the above for better light output.

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post #93 of 484 Old 04-13-2010, 02:44 PM
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Originally Posted by sotti View Post

My understanding is that the only reason we calibrate our displays at all is to emulate what the post houses do.

Calibration in it's purest form is intrinsictly about what the post houses do.

I'll disagree (no disrespect). As far as I know the only clear and unambigous standards we calibrate to are black level, white point and gamut. The other bits (max output and gamma) which are enormously important (hence this thread) are fluid items that inspire more heat than light (especially if you own plasma badumdum). This is another reason why I might say to the OP don't worry, be happy. I'd rather clip at reference than have a display I can read by at 0% and is unable to even see 2.2 from where it's standing.

By the way, if you calibrate for old-school black and white raise your hand.


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post #94 of 484 Old 04-13-2010, 02:49 PM
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Quote:
Originally Posted by Jim McC View Post

... the worst part is I still don't know how to find the proper contrast setting.

There isn't one which is why you don't know how to find. If you want optimal settings you should hire a pro that will work with you toward that end.

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If it isn't clear yet ... there is reference and then there is preference.

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My advice in these situations is to try it and see what you prefer.

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But setting Contrast is more subjective

You can keep asking but the answer won't change.


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post #95 of 484 Old 04-13-2010, 03:00 PM
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Originally Posted by sotti View Post

Increasing film makes view the DVD/BD release as the definitive version of their works. They are there in post making tweaks and changes

That's totally a shame since home reproduction is just a pale shadow of a quality theatrical experience. However ... follow the money.

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....
George Lucas clearly views the most recent DVD release of SW as the most canonical.

Feh, every time someone watches the "fixed" version a puppy dies. That observation is cognizant of limitations that pass with time. My introduction to the world of post was Se7en. The best DVD "extras" ever. David Fincher essentially remade the film in post for DVD because he ran out of money while making the theatrical release.


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post #96 of 484 Old 04-13-2010, 03:22 PM
 
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Originally Posted by bodosom View Post

Well only the film maker gets to see the truth then unless you're suggesting that what comes out the DVD/BD production house is the same as what's on the film. And don't be so quick to blame CE companies. Anyone can look at a DVD and see that it's rife with MPEG errors because of bad encoders or pilot error.

Actually Pioneer tried diligently to do the right thing. They include a switch that turns off clipping and as I said they're the only company I'm aware of that properly processes quantization information in AV Info frames.

And finally I don't think pro/reference monitors can realistically be used as a model of behavior. And not because not even Runco has the nerve to charge $30k for 17" display but because the monitor is just one part of the production chain addressed by SMPTE RPs.

It goes without saying that none of this provides any help to the OP anyone else asking how to "fix" their problems.

The world is full of compromises, and there is no perfect medium or ideal. However, what is seen in the mastering bay is usually what the filmmaker intends. In the old days, there was some distance between what was mastered pure on film, and then afterwards what was telecined for broadcast, DVD, etc. Today, nearly everything gets a DI, so what the director, DP, etc see is really the same thing that gets printed back to film, and that's often the same thing that gets slightly adapted for HD or SD distribution as well. And in a lot of cases, what you are seeing on say BD may actually be closer to what the director saw when making the film than what you see in an average multiplex film print which can often look pretty cruddy.

The reference is always as close as we can get to the original artistic intent, and the best referent we have for that is the master.
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post #97 of 484 Old 04-13-2010, 04:54 PM
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Originally Posted by Mr.D View Post

Just checked some NTSC material off D1.

Its clouds in bright daylight with the sun visible . Not the nicest material in the world looks like old timelapse stock footage telecined from film.

Level tops out at 254 RGB.

If I clip it at 235 and drag 235 up to 254 to mimic the display criteria of the original material...looks truly awful.

this is on a rec 709 lutted workstation

Are you saying if I pop in a DVD or BD movie and look for a bright scene like the one you describe and toggle super-white on and off on my PS3 I'd actually see a difference? Anyone have good examples for this purpose?


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post #98 of 484 Old 04-13-2010, 05:11 PM
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Originally Posted by PlasmaPZ80U View Post

Are you saying if I pop in a DVD or BD movie and look for a bright scene like the one you describe and toggle super-white on and off on my PS3 I'd actually see a difference? Anyone have good examples for this purpose?

less likely if you are output YCbCr instead of RGB.

Most of the issue revolves around the fact that calibrating your TV happens in RGB space because the pixels are physically red blue and green. But the content is in YCbCr space and legal YCbCr values map to values greater than 235 already.

actually an interesting test would be if you got a Red, Blue or Green ramp and toggled superwhite on and off where the cutoff would be for what you could see. With superwhite on you should be able to see to 254, with superwhite off, you'd likely still be able to see >235. But on a grayscale ramp that without superwhite it would clip at 235.

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post #99 of 484 Old 04-13-2010, 05:20 PM
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Quote:
Originally Posted by sotti View Post

less likely if you are output YCbCr instead of RGB.

Most of the issue revolves around the fact that calibrating your TV happens in RGB space because the pixels are physically red blue and green. But the content is in YCbCr space and legal YCbCr values map to values greater than 235 already.

actually an interesting test would be if you got a Red, Blue or Green ramp and toggled superwhite on and off where the cutoff would be for what you could see. With superwhite on you should be able to see to 254, with superwhite off, you'd likely still be able to see >235. But on a grayscale ramp that without superwhite it would clip at 235.

Using the high RGB clipping pattern on the AVS disc, green flashes to 251 (the highest bar in the pattern). Blue and red seem to be clearly visible only up to 243.

With super-white on, all three go to 251.


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post #100 of 484 Old 04-13-2010, 07:47 PM
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The most precise way I've found to set contrast is from the M&S disk, though not with the numbered panels, but with the pattern above them. With Cst too high, one clearly sees two bright vertical bands, and as one lowers it the two bands merge into one. The right setting is just when they merge. With this setting I can see the white bars up to about 251 or so. (On my RS20, with the Expanded HDMI setting, this gives Cst = 6, and Br is -5.)
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post #101 of 484 Old 04-14-2010, 02:22 AM
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I generally use the AVSHD disc and set contrast so that 253/254 are discernable and also that the contrast is not so high that its clipping any of the color channels. ( this part I usually set by eye and then verify with Calman when I calibrate grayscale)

My panasonic plasma will not clip at any contrast setting but it will knacker gamma and grayscale if its too high. You can get white to clip if you change the signal level setting.

My RS1 will clip with the contrast control in a fairly standard manner.

Every broadcast monitor I've bothered to check recently shows white level all the way up to 254.

I can normally tell when I'm watching something (DVD/BD) on a display that is clipping at 235. Like I said try it and see rather than continually discussing it.

In fact my old ancient panasonic DVDA350 (still works fine) always clipped everything below 17 but kept everything up to 254. I guess someone was being sensible by chucking out what wasn't needed to maximise the bitdepth in the processing pipeline for an early player.

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post #102 of 484 Old 04-14-2010, 05:27 AM
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It would be interesting to kind of turn things on its ear and map the YCbCr codes that result in "illegal" RGB codes... where are they in the color space, or are they?

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post #103 of 484 Old 04-14-2010, 07:02 AM
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Originally Posted by jimwhite View Post

It would be interesting to kind of turn things on its ear and map the YCbCr codes that result in "illegal" RGB codes... where are they in the color space, or are they?

Do you mean illegal >235 or illegal <0.

If they are simply >235, they are in gamut, just brighter.

When you go to <0 numbers, well that's what xvYCC does to extend the gamut.

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post #104 of 484 Old 04-14-2010, 07:29 AM
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If possible I will set contrast to make sure there is no clipping with receiver, etc. then I will set it off of ft/L. Every other way for me just does not seem to be consistant. I try to use 16-235 and stay away from component if possible. I set up every customers oppo player using 16-235.

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post #105 of 484 Old 04-14-2010, 08:04 AM
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Quote:
Originally Posted by Mr.D View Post

I can normally tell when I'm watching something (DVD/BD) on a display that is clipping at 235. Like I said try it and see rather than continually discussing it.

Outside of the AVS calibration disc, I have yet to see any difference between super-white on and off when playing a DVD or BD movie. I'm using the YCC color space, since super-white doesn't work in RGB color space on the PS3. I might not be looking at the right scenes, but then again perhaps the difference too subtle for the average viewer to notice.


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post #106 of 484 Old 04-14-2010, 08:14 AM
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Quote:
Originally Posted by Jim McC View Post

I still don't know how to find the proper contrast setting.

The easiest way to set contrast is probably to begin by setting contrast to a very low setting so that you can see all the detail in the contrast pattern. Start turning up contrast. Keep turning up contrast until the detail in the pattern begins to disappear. Now turn contrast down until most all the detail still appears and you can't go any higher without losing detail in the contrast pattern. Without any measurement equipment this sort of a method will probably result in a reasonably high contrast setting that is still likely to deliver all the detail in the original image.


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post #107 of 484 Old 04-14-2010, 08:22 AM
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Quote:
Originally Posted by PlasmaPZ80U View Post

Outside of the AVS calibration disc, I have yet to see any difference between super-white on and off when playing a DVD or BD movie. I'm using the YCC color space, since super-white doesn't work in RGB color space on the PS3. I might not be looking at the right scenes, but then again perhaps the difference too subtle for the average viewer to notice.

There is theory and reality.

Reality is you can still get a very good image with equipment that clips, much of the content is likely to look identical. What we are talking about is a fringe case. People who want their displays calibrated are typically looking for that last 5% of performance. Quantifing the value of WTW and the trade off with dynamic range is the scope of reality.

In theory where we have perfect 0 light blacks yeilding an infinite contrast ratio, WTW is no brainer.

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post #108 of 484 Old 04-14-2010, 08:32 AM
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Originally Posted by alluringreality View Post

The easiest way to set contrast is probably to begin by setting contrast to a very low setting so that you can see all the detail in the contrast pattern. Start turning up contrast. Keep turning up contrast until the detail in the pattern begins to disappear (or you see a color shift from pure white). Now turn contrast down until most all the detail still appears and you can't go any higher without losing detail in the contrast pattern. Without any measurement equipment this sort of a method will probably result in a reasonably high contrast setting that is still likely to deliver all the detail in the original image.

alluringreality, I hope you don't mind me adding about the color shift.
-John


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post #109 of 484 Old 04-14-2010, 08:57 AM
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Quote:
Originally Posted by PlasmaPZ80U View Post

Outside of the AVS calibration disc, I have yet to see any difference between super-white on and off when playing a DVD or BD movie. I'm using the YCC color space, since super-white doesn't work in RGB color space on the PS3. I might not be looking at the right scenes, but then again perhaps the difference too subtle for the average viewer to notice.

I'm not familiar with the setup on a PS3 : as I'm a real gamer and own a 360
You should be able to have it setup to pass full range video from discussion on the net I've seen. Verify that first.

The difference between setting peak white at 235 or 254 is pretty massive visually to me.

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post #110 of 484 Old 04-14-2010, 09:04 AM
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Quote:
Originally Posted by Mr.D View Post

I'm not familiar with the setup on a PS3 : as I'm a real gamer and own a 360
You should be able to have it setup to pass full range video from discussion on the net I've seen. Verify that first.

The difference between setting peak white at 235 or 254 is pretty massive visually to me.

That's what he tested. The PS3 has a switch that is esentially clip or no clip.

With clipping the greyscale clips at 235, w/o it goes all the way up.

But what was interesting is that when he had it set on clipping, he could still see colors above 235 in the individual color ramps.

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post #111 of 484 Old 04-14-2010, 09:27 AM
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I have only looked at ChromaPure HCFR which don't seem to work in this way but it seems to me that instead of 10 zones for grayscale, there should be 11. I know HCFR allows you to free measure. I assume ChromPure does as well.

The highest zone woud be to 109%. If RGB was in balance across the zones through 11 with gamma right for zone 10 would you not almost by definition have a correct contrast setting. You would then choose the highest luminance that you were comfortable with that conitnued to allow the grayscale to have RGB balanced and gamma right.

I don't really know, but I suspect with my set is there is a gamma spike at high saturation. Is there a simple way to calculate what the luminance of 109% saturation should be given a target gamma and the known luminance at 100% and the calibration software's indicated gamma at 90%?

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post #112 of 484 Old 04-14-2010, 09:45 AM
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Originally Posted by gtgray View Post

I have only looked at ChromaPure HCFR which don't seem to work in this way but it seems to me that instead of 10 zones for grayscale, there should be 11. I know HCFR allows you to free measure. I assume ChromPure does as well.

The highest zone woud be to 109%. If RGB was in balance across the zones through 11 with gamma right for zone 10 would you not almost by definition have a correct contrast setting. You would then choose the highest luminance that you were comfortable with that conitnued to allow the grayscale to have RGB balanced and gamma right.

I don't really know, but I suspect with my set is there is a gamma spike at high saturation. Is there a simple way to calculate what the luminance of 109% saturation should be given a target gamma and the known luminance at 100% and the calibration software's indicated gamma at 90%?

Depends on exactly what your target gamma is, but assuming it's 2.2 the...
maxY = 100% Y

Y = (1.09)^2.2 * maxY


So for 2.2 gamma it's about 20% more light than 100%.

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post #113 of 484 Old 04-14-2010, 11:07 AM
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Originally Posted by dsskid View Post

alluringreality, I hope you don't mind me adding about the color shift.
-John

I agree if you're just using a grayscale pattern to watch for a loss of detail there will likely be some color shift, but it probably won't creep down to white if you're using a pattern that has above white detail like the thread title. A step further would be things like watching for color shift and seeing what happens with colors, but I was just trying to keep things as absolutely simple as possible. Really it's just the Digital Video Essentials description for setting contrast. The images from http://www.avsforum.com/avs-vb/showt...2#post16929442 show what happens as contrast is turned up and detail is lost near white on their bars and ramp pattern.


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post #114 of 484 Old 04-14-2010, 11:35 AM
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Quote:
Originally Posted by Mr.D View Post

I'm not familiar with the setup on a PS3 : as I'm a real gamer and own a 360
You should be able to have it setup to pass full range video from discussion on the net I've seen. Verify that first.

The difference between setting peak white at 235 or 254 is pretty massive visually to me.

It does show all bars above white with super-white enabled on the white clipping pattern and APL clipping pattern. Turning super-white off clips WTW and BTB. RGB output doesn't allow super-white, so YCC must be used. Like I said, maybe I'm not looking at the right scenes in the right movies, but it is odd that I've never seen a difference even though I have toggled that setting on and off during movie playback countless times to see what it did with real program material. Perhaps there are other factors in my setup that make the difference unnoticeable to the eye.

BTW, I have both a PS3 and a X360. The X360 may have many good games but it's not the best DVD player as it's noisy and has fewer controls/info for the DVD interface. It also can't do Blu-ray.

UPDATE: I just saw a 3 hour Blu-ray movie (XIII: The Conspiracy) that had plenty of bright scenes and scenes with bright areas. Some of these scenes were extremely bright or had extremely bright areas. I checked super-white on/off for as many as I could sometimes zeroing in on a single frame to capture the brightest image on-screen. I found zero difference time and time again. No difference whatsoever.


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post #115 of 484 Old 04-14-2010, 12:13 PM
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Quote:
Originally Posted by sotti View Post

Depends on exactly what your target gamma is, but assuming it's 2.2 the...
maxY = 100% Y

Y = (1.09)^2.2 * maxY


So for 2.2 gamma it's about 20% more light than 100%.

Thanks Scotti,

I am assuming that if my target gamma is 2.35, I would just use 2.35 as the exponent in the above formula?

The DUO is going to give me no way to control 109% but at least I can determine if I my gamma is spiking at above white as I suspect.

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post #116 of 484 Old 04-14-2010, 07:18 PM
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Y Pb/Cb Pr/Cr Super-White (HDMI): On

This setting controls whether the PS3 will pass blacker-than-black and whiter-than-white parts of the video signal. It's really only useful during calibration, which is why we leave it turned on. Many discs don't contain material in above white or below black.


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post #117 of 484 Old 04-14-2010, 07:35 PM
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Quote:
Originally Posted by gtgray View Post

Thanks Scotti,

I am assuming that if my target gamma is 2.35, I would just use 2.35 as the exponent in the above formula?

The DUO is going to give me no way to control 109% but at least I can determine if I my gamma is spiking at above white as I suspect.

if you've got a duo, you're best bet is to calibrate 109% in the display, then use the duo to correct the rest of the grayscale.

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post #118 of 484 Old 04-14-2010, 07:46 PM - Thread Starter
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Originally Posted by alluringreality View Post

The easiest way to set contrast is probably to begin by setting contrast to a very low setting so that you can see all the detail in the contrast pattern. Start turning up contrast. Keep turning up contrast until the detail in the pattern begins to disappear. Now turn contrast down until most all the detail still appears and you can't go any higher without losing detail in the contrast pattern. Without any measurement equipment this sort of a method will probably result in a reasonably high contrast setting that is still likely to deliver all the detail in the original image.

When you say "detail in the contrast pattern", do you mean the bars on the bottom?
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post #119 of 484 Old 04-14-2010, 11:57 PM
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Originally Posted by Jim McC View Post

When you say "detail in the contrast pattern", do you mean the bars on the bottom?

If you've ever tried the Monster ISF HDTV Calibration disc, the contrast adjustment is made by using a person in slight motion wearing a white shirt, with white buttons.

As you adjust contrast, the buttons, as well as the areas of shadows on the shirt caused by the fabric, will disappear as the contrast is raised too high. This is where the detail in the contrast gets lost.

People get caught up in the black levels losing detail, though they may not realize the same happens at the opposite end of the scale.


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post #120 of 484 Old 04-15-2010, 02:38 AM
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Originally Posted by PlasmaPZ80U View Post


UPDATE: I just saw a 3 hour Blu-ray movie (XIII: The Conspiracy) that had plenty of bright scenes and scenes with bright areas. Some of these scenes were extremely bright or had extremely bright areas. I checked super-white on/off for as many as I could sometimes zeroing in on a single frame to capture the brightest image on-screen. I found zero difference time and time again. No difference whatsoever.

brrrrr! Terrible film that and 3 hours long...nasty.

here's what wikipedia has to say about rec.709.

Interface codes 0 and 255 are used for synchronization, and are prohibited from video data. Eight-bit codes between 1 and 15 provide footroom, and can be used to accommodate transient signal content such as filter undershoots. Eight-bit interface codes 236 through 254 provide headroom, and can be used to accommodate transient signal content such as filter overshoots and specular highlights.

As far as I'm concerned you want to be able to see the difference between specular highlights and level lower than that. By that logic...you want to set your display to show everything up to 254. 254 being mapped to the whitest point the display will reliably depict without incurring clipping in any of the color channels.

I'll have a look at some material over the weekend but like I said you can find evidence from S&M posted on here that demonstrates consistent level above 235. I have to say again I usually notice if range above 235 is clipped off on most material including broadcast TV over here in the UK.

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