Originally Posted by locki
I second this request? Any cheap and nasty way to do this? The black crush is killing me on an otherwise great projector
The black crush and loss of shadow detail is because the JVC's default gamma curve is backwards, and to make it worse, it also drifts over time. Even Chad's pre-calibration gamma measurement shows it being backwards before he fixed it, but on a unit with more hours it might be even worse than his graph shows due to gamma drift.
Without a meter, here is what you can do, first make sure your brightness is set to around -6 and contrast to 12-13 if using enhanced mode on bluray, otherwise I believe you should set these at 0 (you'll be able to tell easily which one you need to use (-6 vs. 0), because the blacks will be obviously off if you choose the wrong brightness and contrast.
Next, go into the custom gamma editor, and choose a numerical gamma preset
that looks best with your unit for BRIGHT SCENES
(probably 2.3 to 2.4 if on a new lamp, but if older lamp (100+ hrs), then maybe 2.6 if it has drifted). You may need to watch a few different bright scenes for about 5 minutes and keep changing the gamma preset number (2.3 to 2.6) back and forth to decide. After you find the one that looks best by eye in bright scenes ONLY, move onto the next step...
Next load a dark scene for reference (something from a movie or whatever, or use the AVS test disc or Disney Gamma editor, or something) and go into the custom gamma editor on your JVC and increase the output value of the white gamma point at 5,10,15,20 IRE's until the shadow detail looks about right, and compare a few different dark scenes and make sure the blacks look rich still but also have shadow detail. Keep increasing the white gamma until it looks correct. When adjusting the gamma, increase each IRE by about the same PERCENTAGE amount (hence if you raise 5 IRE by 10 output points and it started at 30 (that's 33% increase), raise all the 5-20 IRE white gamma points by the same percentage I believe (you can try it both ways, raising each one by the same numerical amount or by a percentage amount). I'd say increase each one by 10% as your first attempt, then try 20% if that didn't help enough. You probably do not need to do this to IRE's over 20 (25-95). The white gamma editor is fairly simple to use once you figure it out, but the remote clicking procedures are awkward. What this will do is lower the gamma value in the dark scenes increasing shadow detail. Don't adjust things too extremely, just get it to the point where it looks good enough.