Originally Posted by PlasmaPZ80U
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.