I've posted quite a bit about the calibration of my 42rv530, and I'm sure you guys are all getting sick of it. (It's a display that is simply unwilling to be close to correct).


So I if I open up the cuts and gains, contrast and brightness so that 10% black is @ 2.2 gamma and 100% is D65 and just below clipping I get a pretty even greyscale with a little dip in color tempeture and max dE of about 5-6 (not great but not the worst). But the problem is starting at about 50% my gamma starts falling like a rock to around 1.7, wich leaves very washed out highs.

To compensate I need to sacrafice contrast dropping the contrast from 100 to 50 (after the service menu had been calibrated for the above) or lower. This signifigantly throws off my greyscale, it moves the blue dip previously at 60-70% to closer to 80-100% meaning to have white be white I need to raise the blue drive. Unfrotunetly blue is the strongest signal on the lowend so I end up having to raise red and green to get grey balanced down low, wich ends up adding signfigantly to my black level. As the cuts and gains interact, raising red and green on the lowend mean raising blue more at the high, then back to low. And by the time I'm done doing all this my gamma has fallen off a little bit more and now I need to push it down some more.

In the end I've reduced the brightness of the display by close to 50% without touching the backlight and almost doubled my black level. But I'll have an average gamma of maybe 2.1 w/ 90% at a gamma of 2.0 v where I started with an average gamma of maybe 1.85 w/ a 90% at 1.65.

The one thing I have nagging in my mind is that there is a gamma control in the user menu, but I don't see a corresponding serive menu option.

Is there anything I can do other than simply make a compromise, (niether perfect greyscale nor perfect gamma)? Is there anything anybody knows about toshiba LCDs for deeper level calibrations.

Would an ISF guy be able make this set sing like I wouldn't believe?

Is there anything I can do other than simply make a compromise, (niether perfect greyscale nor perfect gamma)? Is there anything anybody knows about toshiba LCDs for deeper level calibrations.

Would an ISF guy be able make this set sing like I wouldn't believe?

At some point, it is all about compromise. You have to decide which one you can live with. Personally, gamma is the one I would sacrifice.

If the calibrator is familiar with your set he may be able to get a better result since he would be familiar with the interactions of the controls.

You mention that there are controls in the user menu that you have not tried. You should also see what effect those have. In many cases the service menu settings set the mid points or min/max values of the user controls so you also need to adjust the user menu AFTER adjusting in the service menu.

You mention that there are controls in the user menu that you have not tried. You should also see what effect those have.

Unfortunetly what I was saying that the gamma user menu item can't be adjusted beyond what's in the user menu (where everything else can be taken to an extreme with the service menu). I've tweaked EVERY item in every menu I could find to try and get this thing right.

And gamma is the biggest victim of compromise at this point, followed by grey scale at the dark end of the scale.

Sotti,

I think with all consumer displays at some point compromises have to be made. In your case, I think if lowering contrast so far down makes the picture too dim and throws everything else off as well then you made need to sacrifice better gamma in order to get everything else fairly good. You're not alone. I've calibrated a few older Toshiba CRT sets and they exhibit the exact same gamma response as you describe starting at 2.2 and then dropping to around 1.7 at the other end and that was after compromising a bit on contrast.

In the end, you may want to lower contrast some to help with gamma if you're noticing a veiled washed out look at the higher end.

I can't recall - did you post your calibration file for both scenarios that you described.

cheers,


--tom

Sotti,

I think with all consumer displays at some point compromises have to be made. In your case, I think if lowering contrast so far down makes the picture too dim and throws everything else off as well then you made need to sacrifice better gamma in order to get everything else fairly good. You're not alone. I've calibrated a few older Toshiba CRT sets and they exhibit the exact same gamma response as you describe starting at 2.2 and then dropping to around 1.7 at the other end and that was after compromising a bit on contrast.

In the end, you may want to lower contrast some to help with gamma if you're noticing a veiled washed out look at the higher end.

I can't recall - did you post your calibration file for both scenarios that you described.

cheers,


--tom

I did, here they are again though I'm not sure i actually have one that nailed the lowend gamma where the highend goes to 1.7, (plenty of 90% at 1.7).

I'm setting into my compromised picture.

I do want to take one more pass though.

Sotti,

In looking at 3-24 vs. 3-26, I'd say that the grayscale looks a bit better in 3-24 but in 3-26, you still seem to have a good bit of light output at 100 %. It looks like the big difference is at 20 % where in the 3-26 readings, it begins to spread out.

I wouldn't worry that much about on/off contrast ratio since the gamma response is really what is defining the contrast of the display. Black's Y value has gone up in 3-26 so the only real question is if you notice that black looks more gray than black. Do you have a backlight control - I'm assuming yes. You could find a halfway compromise with contrast and then use the backlight to drop overall luminance so black has less light output yet still end up with about 120 Y for 100 %. That assumes that the 3-26 readings look ok to you in your viewing environment i.e. the picture is not too dim. I would think with 33-35 ftls that that should be bright enough unless you have a lot of ambient light.

Another interesting point is that your primary color points moved a bit between 3-24 and 3-26. I don't know if this is variance with the probe or if indeed those readings are repeatable i.e. the points really do move because of the changes to the settings. In either file, your brightness levels for the primaries look very close to what the color gamut calculator says that they should be if my math is correct.

hope this helps,


--tom