http://www.spearsandmunsil.com/articles/technicalnotesonthepatterns.htmlIf luma is clipped, but R, G, and B aren’t clipped, your first assumption should be that contrast is set too high. Turn down contrast and see if the clipping goes away. If it doesn’t go away, then the player or display is clipping the high luma range. To figure out whether it’s the player or the display generally requires either test equipment or temporarily substituting a different player and/or display.
Originally Posted by chronitis
When I first got my set I was confused why I couldn't see any white steps above 235. I thought that the wtw and btb were not passing through. But after talking to sony engineer, he explained that my set is doing exactly what it should. Every bar flashes from 16-235 as per tv reference levels. The wtw and btb levels are for color and they do pass through on the set. On the color clipping chapter of AVS709 I can see bars above 235 for all colors.
If you see the white blocks above 235 on the white clipping then your blu ray players dynamic range could be below 235, i'm just guessing around 219. Thats what the article is saying when it says "it was possible to see all of the white blocks since they were adjusted down below where the contrast was calibrated, but on the OPPO, the WTW blocks correctly blended into the white background".
It is interesting that my PC behaves identically to my BD player; who'd have thought Nvidia and Sony would screw up in the same way? And again, the article says the bad dynamic range caused gradient problems. I stated the gradients they're likely talking about (a more meticulously written article wouldn't make me guess about this and other things!) are perfectly smooth, not "blocky" like theirs were, and they conform to everything Spears and Munsil have to say about them. If what the article said applied to my system, I would observe the problem it described with the gradient. But I don't, and I conclude the article does not apply.
Furthermore, on the AVS709 Grayscale Steps, I took a screen shot in XBMC. The 25 bars range from RGB(1,1,1) to RGB(253,253,253), and the 25 rectangles in the top strip have values 1, 5, 16, 26, 37, and then continue increasing in steps of 11 (with one 10 if I counted right) up to 245, and then they end with 253. All these rectangles are distinguishable, except of course for the two BTB ones, as they are full black at default brightness. The WTW ones are visible at default brightness and contrast. As I've stated several times, my BD player looks just the same. I don't see how this is consistent with your idea that my BD player has a reduced dynamic range or your latest claim about what some Sony "engineer" told you.
Now regardless of what spear and munsil says you shouldn't see flashing above 235 as the set is automatically at tv levels. Some other t.v.s i've owned do pass 16-255 automatically, allowing you to see all the wtw bars on the white clipping test. This t.v. only does 16-235 by default and allows just the wtw and btb colors (not whites or blacks) to pass.
Well, no. I can take a screenshot of XBMC flashing AVS709 White Clipping and verify in a paint program the background is RGB(253,253,253). While the bars say 230, 231, ... 253, they actually contain values one less than that, and bar 253 (really 252) is just barely visible against the background 253, with all the bars progressively blending in up to that point just like they should. When I play the same test pattern in my BD player, I see the same thing. Ditto for the S&M patterns. As for BTB, if you don't see it when you turn up brightness, that's another indication that something's out of whack with your system.
To the extent I can make sense of the hometheaterhifi.com article's prose, they are not describing the behavior of my system. It's not even close.
I think they might be. Your blu ray player is older than the one in the article as you state. A lot of older sony blu ray players have this problem.
Sigh. You are again asserting without evidence that my 2008 2D Bluray player has the same problem as a 2010 3D player, a problem that was fixed in firmware for the latter, and you're implying it wasn't fixed in a firmware update for my player, if it even had the problem to begin with. Furthermore, for what you say to be true, my Nvidia GT430 has to have the same problem, because it behaves the same way. Another big part of your thesis relies on information about WTW/BTB clipping you got from some unidentified Sony engineer; my experience contradicts what you were told, and the Spears and Munsil link I gave you lists alternate causes for what you're seeing. Still another part requires you to ignore the fact that the gradients look exactly how they should on my system, while the article you consider gospel talks about them looking blocky due to poor dynamic range. I could go on.