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Setting contrast with Spears and Munsil disc - Page 17

post #481 of 484
Glad I stumbled upon this thread, read from the start, almost as fascinating as the (now defunct) insider thread in the HDTV/BR forum I spend a lot of time reading.

From amirm who led the development of the VC1 (MS) codecs to posters representing AVC, the HDTV/BR consortium's and some studios (Paramount comes to mind) that thread was insightful and worthwhile even though much of it was above my pay grade.

Perhaps one of you would PM amirm to take a look at this thread, he might want to chime in. He mostly hangs out at the +20,000 projector forum.

IMO the codec developers would have some opinion on this subject.

Personal experience.
My LG 55LH90 maxes out at over 80FL, searingly bright and calibrated to 30-35 FL with Backlight set to 30 and reduced by the energy savings control to about 12. Clipping not an issue here, neither is light output.
The LG BD390 clips badly above 240, the Panasonic BD65 does not clip to 254 measured with S&M.
The venerable old Panasonic S97 does not clip measured with DVE. Old timers will remember this up scaling player from the DVD shootout where it almost rivaled the Denon players from that era.

My LG is calibrated with ChromaPure and a Chroma 5 and has excellent PQ judged by many recorded OTA broadcasts of PGA Golf and Nascar races recorded on the TivoHD.

I have a collection of HDDVD and BR movies, many stored on a WD 2 TB mybook connected via a Cat5 hardwired link from a Netgear 3700 to an Asus Media server and some still stored on the computer.

Any suggestions for WTW tests within my expertise would be appreciated.

Here is a link to the LH90 calibration:
http://www.avsforum.com/avs-vb/showp...&postcount=384
post #482 of 484
Easiest thing to do is read through the thread and try the practical implications of the issues under discussion.

Namely try 254 as your peak white and try 235 as your peak white and then give it some wiggle room up to 240.

I'd be interested in hearing people's opinions of running these various ways. Its all very well looking at some charts and seeing how the numbers fall.

I'm convinced 240 is a good place to put white. In an ideal world targeting 235 would also fine. No reason to limit your contrast capability retaining detail that doesn't do anything meaningful.

I'd say there has been a lot of meaningful evidence put forward on this thread without resorting to argument and esoteric goalpost moving to recommend somewhere lower than 254.

The facts are we are finding precious little real picture information above 235 , dial in some wiggle room to account for variance and 240 would seem to be a sensible proposition.

Again don't just cling to a specific number try it with an open mind and let us know what you think.

What looks better 254 or 240?
post #483 of 484
Quote:
Originally Posted by Mr.D View Post

Easiest thing to do is read through the thread and try the practical implications of the issues under discussion.

Namely try 254 as your peak white and try 235 as your peak white and then give it some wiggle room up to 240.

I'd be interested in hearing people's opinions of running these various ways. Its all very well looking at some charts and seeing how the numbers fall.

I'm convinced 240 is a good place to put white. In an ideal world targeting 235 would also fine. No reason to limit your contrast capability retaining detail that doesn't do anything meaningful.

I'd say there has been a lot of meaningful evidence put forward on this thread without resorting to argument and esoteric goalpost moving to recommend somewhere lower than 254.

The facts are we are finding precious little real picture information above 235 , dial in some wiggle room to account for variance and 240 would seem to be a sensible proposition.

Again don't just cling to a specific number try it with an open mind and let us know what you think.

What looks better 254 or 240?

On my display, I can either do 254 or 235. 240 is not possible since my display won't clip above white at max contrast, only color-shift. Therefore, I either clip white to 235 at the PS3 or not. The Xbox 360 permits WTW in all cases, yet I don't see color-shifting at max contrast. I have tried various contrast settings in both cases and don't seem to see any need to pass WTW, regardless of the contrast setting.
post #484 of 484
Quote:
Originally Posted by PlasmaPZ80U View Post

On my display, I can either do 254 or 235. 240 is not possible since my display won't clip above white at max contrast, only color-shift. Therefore, I either clip white to 235 at the PS3 or not. The Xbox 360 permits WTW in all cases, yet I don't see color-shifting at max contrast. I have tried various contrast settings in both cases and don't seem to see any need to pass WTW, regardless of the contrast setting.


Thanks for sharing good to hear other people's experiences.

Forgive me if I've posted this before as I'm very busy at work.

I have a number of options to control white mapping.

Currently I'm running a panasonic 42phd8 plasma ( I do have a jvc HD1 but its in mothballs until my home cinema building gets built).

I can use the plasma itself to control white mapping.

The contrast control will not clip at any level and it behaves more like some sort of pivot based s-curve. I set this by looking for "humping" in the gamma mainly near black and set it at the point of least crushing. This varies in a non-linear fashion ie: 1 is awful , 21 is good 22 is awful , 25 is good. If its set too high it causes a blue run out.

Luckily the plasma has an "input level" control which gives very precise control over where white is mapped to on the display so I can use this to clip white lower down at 235 or 240. However it also introduces a blue run-out ( I could probably stop this by itterating between contrast and input level adjustments if I put my mind to it.

The result of the blue run-out is negligble in normal use however.

However I run the plasma at 254 specifically to stop any possibility of run-out.

I then use John Adcocks' Upsilon mixer software to automatically profile the plasma in this state and then create correctional LUTs for various color standards and gammas and white points. This works brilliantly.

For apps that run in overlay ( TMT in my case) I use the picture control sliders ( I run it in software mode) to clip white at 240 although John's software once again makes sure the default levels coming out the card are correct (full range video).

Other less critical sources (xbox 360) I just use the plasma hardware to set the white point.

So far I'm very happy with 240 for all sources. I suspect I could go down to 235 for most BD material but 240 provides a bit of wiggle room just in case.

Switching back to 254 gives no improvement to white detail but carries an associated contrast penalty relative to 240.
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