Originally Posted by CrocHunter
Is it common to raise UBOF 4-5 notches to get shadow detail? is my SBRT setting too low at 20? This is very frustrating, the DVE disc does'nt help much either in explaining the other test patterns for brightness and contrast.
First, it's *very* important to understand that black level is established in several places that interact -- or add together, depending on how you look at it.
(1) Globally, 2170P-1 - RCUT-BCUT contribute as much as SBRT, #4 below. If you raise them all up a couple of notches, you have raised black level as if you had raised SBRT.
(2) 2170P-1 - YOF is an offset that affects black level. Here, the settings are dependent on input video rate *and* video class (YC, component, HDMI, MS/ATSC tuner). I have left them for now set as they came from the factory.
(3) 2170P-4 - BLK, if anything but zero, invokes a dynamic black-level feature that will drive you nuts. It's 0 (off) in Pro mode, but you have to make it zero for the other modes (highly recommended). Until you do this, experiment with black level *only* in Pro mode.
(4) 2170P-1 - SBRT is the fundamental global black-level setting. When I set my drive and cutoff values (RDRV thru BCUT) for the first time, I set SBRT to 31, and then adjusted the RGB cutoffs (#1, above) for a reasonable black level, in the right ballpark. It was originally *way* off for my purposes.
(5) 2170P-3 - UBOF is for balancing black levels among your variious input classes, video rates, and picture modes. If you do set one of them to 0, make sure it's the input/source with the highest black level or you'll have nowhere to go with the others if you have to make them darker. One notch of change here = about two notches in SBRT.
Yes, it is complex, but there are different methods you can use to get a good black-level adjustment.
First, be aware that standards are very sloppy or nonexistant for black level over component cables. The exact voltage for black (green cable) differs from player to player, from one manufacturere to another, and also depends on whether you have set any features on the player, such as lighter-darker, super-black, extended black, etc. My Normal setting for my retired (and excellent) Toshiba 3650 was *very* high; but the Normal setting on my new Panasonic S97 is about the same as broadcast and S-video. Go figure. All you need to do is balance the black levels with the 2170P-3/UBOF settings.
Here is a method that will work. If you want to establish an SBRT setting at its center (31),
(1) play a PLUGE pattern from AVIA or DVE over S-video;
(2) set SBRT to 31;
(3) adjust 2170P-1 - RCUT thru BCUT for a neutral and correct black level. If you have already gotten those cutoffs just right, you might try changing them each by the same amount, so color is not affected. (No guarantees.)
(4) move the DVD player to the component inputs, and trim black level with UBOF for that video rate.
Now . . . *that* gets you in the ballpark, and it doesn't matter if, after tinkering in great detail, you end up with SBRT a few points different or whatever, you have gotten the settings near the middle of their ranges.
One could argue that the UBOF balancing settings could be started off at 3, so you can go either way to make an adjustment. I have no evidence that there are "correct" settings for UBOF; they're for compensating for differences. So one could start with UBOF at 3 for each input, then do steps 1-3 above, and then refine the adjustments for UBOF. I don't think it matters a whit how you do it, but I would confine myself to balancing out SBRT, the RGB cutoffs, and UBOF in Pro mode. (Leave YOF alone.)
The argument for setting SBRT in the middle of its range isn't a strong one. It feels "right" to me, a career electronics and computer engineer. I can't argue for changing anything if you already have a set of satisfactory values for the cutoffs, and SBRT is at, say, 15. My set came with SBRT at 20! The service-manual charts, however, show defaults for different model TVs at 31 for SBRT. So 31 is obviously okay, and I was starting over with the cutuff settings. So I followed the above procedure to great satisfaction.
Example settings for my 36XS955, approx 6500K white, color Neutral, DVE pluge:
UBOF = 3 or 4., depending on input. Mostly 4. (DVD player on V5 was 0, now 4.)
SBRT = 31
RDRV - BCUT = 43-27-21 - 40-21-22
Another example for friend's 34XBR960, approx 6500K white, color Neutral, DVE pluge from late-model Toshiba player:
UBOF = untouched from factory; unknown.
SBRT = 31
RDRV-BCUT = 40-27-24 - 38-20-26
Note that the *sum* of the three cutoff settings nearly match, at 83-84. But there were color differences between his set and mine, with red-blue differences in the settings, eay to adjust. I started with *my* settings on *his* TV, then tweaked them for correct color. Worked like a charm. Used a transportable small computer with a calibrated 6500K screen as a standard.
This discussion has been about *just* black level ("brightness"). Contrast ("picture") is another set of adjustments entirely, overlapping the above only in the three RGB drive settings. I have found new ways to balance the contrast between different sources, too, and the settings are in different places: 2170P-4 - SPIC (for different input classes) and 2103-1 - SCON for balancing SD broadcast against S-video inputs (say, your VCR).
Further, no matter what I have said before, there are two places where sharpness is very significantly controlled *in addition* to 2170P-3 and the MID5 table. I'll write that up soon. I have some substantially improved image settings to recommend for different sources, based on these (for me) recent discoveries. Surprising improvements for SD broadcast and SD over S-video, and for DVD on component inputs, less so for HD broadcast.
Have I clarified this, or made matters worse? Gimme feedback!