Setting White Level (picture/contrast)

[glaufman]

Hi All-
I could use a little advice on calibrating TVs... I've played around with the THX optimizer, but I feel the white level setting leaves a little bit to be desired in terms of objectivity... I have DVE and Avia on the way, but don't know if they do any better in terms of setting the absolute white level...

I remembering reading somehwere (unfortunately at the time I didn't pay it enough mind to recognize its importance) that the white level should be measured with a proper meter and set to 35 ft-somethings...

Does anyone know what this correct measurement is (along with the units) and perhaps could point me to an inexpensive light meter that reads in such units?

Someone else told me this was only for projection screens, but it seems to me it would make sense to have a standard for all tvs...

[salvasol]

Welcome to the forum

When I calibrated my TV I used DVE ... I didn't use anything to measure the changes ... I think the best reference to calibrate is your eyes

If the brightness, color, etc. bothers you ... you need to adjust the TV to your taste ... use DVE, AVIA, etc as an starting point .. unless you hire a professional to calibrate your system

[tonyvdb]

glaufman wrote:

Hi All-

Does anyone know what this correct measurement is (along with the units) and perhaps could point me to an inexpensive light meter that reads in such units?

Have a look Here it should shed some light on the subject for you.
By setting the proper Black level using the AVIA or DVE setups that you will get this will help you dramatically.
To set grayscale to the NTSC standard of 6,500 Kelvin, set contrast, brightness, color, and so on using test patterns designed specifically for each of these controls; You will usualy need to adjust the "red push" in the color decoder when possible in the service menu.
But yes to do it right you need a color analyzer to calibrate a set properly.

[glaufman]

Thanks for the info... I do have the cal discs on their way, but I'm concerned they won't be much better for white levels than the THX disc.. I'm not talking about color temp here (6500K) but much more simplistically, the white "level." for instance...
On the THX disc they show 8 boxes with varying degrees of white and light gray... the instructions are simply to make sure "whites look white, but that all the different boxes are distinguishable from each other"... this leaves a lot open to interpretation...
Are the patterns on Avia or DVE any better?
Is there no measurement to make for how bright a white should look? I remember now that the same article I read said something about holding a 1 inch flame from a cigarette lighter 1 inch from a piece of white paper, and even though the color would be off, that was the approximate brightness you wanted...

[tonyvdb]

Unfortunately the THX optimizers leave something to be desired. The DVE or AVIA DVDs will give you much better results.

[tonyvdb]

glaufman wrote:

Is there no measurement to make for how bright a white should look?

Its not so much how bright white should be but how white it should be when you plsy with the Settings that adjust the white level "Natural, Cool or even Movie or Sports" these will all affect how the white looks (slightly red or blue). Natural is usulay the recommended setting for most people as it tends to give a slightly red look to flesh tones and this keeps the greens and blues from being to harsh.

[lcaillo]

Color temperature and white level are two different settings. Color temperature is set using a reference gray scale or with a meter, or with visual estimation. White level settings will depende on the type of display and what you are trying to accomplish. What set do you have?

[glaufman]

Right... once again, I'm not talking color temp here...

My TV is an "old" Panasonic CRT, standard def... but I'd like info for other technologies as well, including Plasma, LCD, etc...

[lcaillo]

The answer would be different for different displays, even different models if you get down to really calibrating the set with the right equipment. Generally, with a CRT you will set the white level to the point just before it loses focus, or just before the power supply loses regulation, if possible. For the most part, setting to a particular light level is not relevant. DVE and Avia have guides for these settings.

[glaufman]

Curiously, though I still can't find the article I'm looking for, I did find this sample cal report... the last graph in the report alludes to what I'm talking about, with what I believe is a 16 fL white level... I suppose fL stands for foot-somethings....
http://mysite.verizon.net/resp4oz4/s...ion_report.pdf

[lcaillo]

Foot Lamberts. Generally for projectors in theater setups, some suggest shooting for around 12fL to be consistent with the SMPTE spec for theaters. It largely depends on the application and light control, but most people would be happier with a higher level. For most displays we calibrate for the maximum contrast with the best color and gamma tracking and ability to resolve detail.

[glaufman]

What exactly is a lambert?

[glaufman]

Also, I found this, and would love feedback on what it says about white levels...
http://www.avsforum.com/avs-vb/showthread.php?t=852536

[lcaillo]

Tom makes some assumptions that may or may not be relevant to everyone. I prefer to optimize white level based on gray scale tracking and gamma. Most of his information is very good. The numbers for various displays may or may not be apropriate.