Calibrating the Infocus X1 with AVIA, some help needed.

Inspector Hammer! · 10-03-2005, 01:31 AM

I've had my X1 for almost 2 years now and think that I have it pretty well calibrated using my good ol' AVIA disc, but I just want to see if i'm doing it right in two area's, black level and white level.

Now, on the black level test patteren, I have my black set as instructed on the tutorial, so that I can just barely see the vertical bar on the right moving back and forth but cannot see the left one. Is this correct for a projector?

On the white level test patteren, I use the lower portion of the screen and pretty much set white the same way as black, only this time I set it so that I can see BOTH vertical bars moving back and forth, with one just brighter than the other. Is this correct?

If i'm doing something wrong please let me know and point me in the right direction, i've calibrated countless CRT sets with AVIA and have that down, but I just want to confirm that i'm using it correctly on a DLP projector such as the X1, thanks.

Inspector Hammer! · 10-03-2005, 12:20 PM

Gregg, Vince, Guy...anyone?

Inspector Hammer! · 10-03-2005, 09:55 PM

I'll give this one more shot before I let it slide off the page, I just need instruction on setting black and white levels on my Infocus X1 using AVIA.

Please, I need to know if i'm using AVIA correctly on a DLP projector.

ChrisWiggles · 10-04-2005, 01:35 AM

On a digital display you want to maximize your contrast range as much as possible. On an DLP like the x1, you can use mirror dithering to set black level with extreme precision. Throw up any of the black patterns, and observe the black background, which is at video 16 (black). You should set this so that the mirrors are off, or one click above this so that you see them dithering. You should see both black bars on the Avia patterns, as they are encoded above black. There is no below-black elements on Avia.

For white, on a digital display you are looking for clipping or colorshifting. Some displays will hard-clip white, and others will clip at one color before the others which will show as a colorshift. Note how this is very different than calibrating a CRT's white level. Both of the moving bars on Avia are below reference white(235) so they should ALWAYS remain visible. You should raise your white level until the larger white portion (which is brighter than the bars) begins to colorshift, or you begin to see that portion clip down until the bars below white are no longer visible as distinct from white. You should stay a few clicks below the point of clipping or colorshifting. This will maximize your white point.

Now, you may want to return to black, and go back and forth between black and white a couple times as the controls may interact, so it is an iterative process.

***advanced note: It is preferable for some demanding viewers, to align the peak white of a digital display to peak white 254, rather than reference white 235 so as to prevent any peak white highlight detail clipping. This will reduce the contrast range between black and reference white slightly, and your in-scene contrast will be slightly less, but you will maintain data the extends beyond reference white. This is a subjective choice by the user on displays that have limited contrast ranges, unlike the unlimited range provided by CRTs that does not prompt this choice. To do so, you will need to use patterns that extend to peak white, such as those on Avia PRO, or DVE.

Jim Mcc · 10-04-2005, 02:43 PM

John, I also have the X1, but I don't have Avia. I hope you can understand what Chris said, because I sure don't.

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Inspector Hammer! · 10-04-2005, 03:05 PM

Well, it took me a couple of times reading his post, but I think I got the jist of it. Basically what he's saying is that you should see BOTH moving vertical bars on BOTH the black and white test patteren, turning the black and white level up or down until one bar is visible and keeping the level at just before the point where the other bar next to it disappears into the background.

I can see how you would get confused, Jim, if you had AVIA and were familliar with it's patterens it would be clearer to you. You should most definitely look into picking up AVIA, it's an INVALUABLE HT tool and I don't see how I got along without it.

BTW, Chris, I made the adjustments last night based on your post and I must say that I am impressed with the results! It turned out that I had the black and white levels down one notch too low which resulted in my image being too dark, which was my #1 complaint about the X1, but those adjustments perked it right up and it looks very good now.

ChrisWiggles · 10-04-2005, 05:27 PM

Quote:

Basically what he's saying is that you should see BOTH moving vertical bars on BOTH the black and white test patteren, turning the black and white level up or down until one bar is visible and keeping the level at just before the point where the other bar next to it disappears into the background.

That is correct. All the moving bars in Avia are *within* the range from black to white. The black bars in Avia are both *above* black. The white bars are both below white. If the bars are clipped off, then you are losing shadow detail near black, and obviously you'll be losing white detail near white.

The black bars may become obscured using a very high APL pattern (like the half-white pattern in the advanced menu) if your system has very low ANSI contrast. With most digitals, however, this is not really a problem because the black level of the display is elevated enough, and ANSI contrast is high enough that the visibility of the bars doesn't really vary with APL. On CRTs, this is more complex, because if you throw up a full black pattern with the bars and calibrate, then switch to one with half gray or white, ANSI washout will render the bars invisible. On CRTs then it is a little more complicated because the ultimate black level you arrive at will vary depending on the APL of the pattern, and the pattern you choose can depend on your preference for total black-out, or rendering all the shadow detaisl even in bright scenes (high APL).

ChrisWiggles · 10-04-2005, 05:29 PM

And remember, if you have a DLP, use dithering to find your black point by going up to the screen and observing the dithering. This will provide extreme precision compared to paying attention to the bars. Just observe the black background and find the point where the pixels start/stop dithering, that's your display's black point. At this point, the bars should all be visible, because they are all above black (on Avia; on DVE there are additional bars that are below black).

Inspector Hammer! · 10-04-2005, 05:33 PM

Chris,
can you please explain what 'dithering' is for me so that I know exactly what to look for in the image? Thanks.