CurtPalme.com Home Theater Forum

[HRBO]

Picture in post is After calibration i HCFR, which render the bad greyscale in testpattern.
Have done a check regarding 20pt Greyscale to confirm that the 65,75,85,95 areas not shown in 10point is way off

Will try again with lower starting contrast, as I started with +10 to achive as high lightflow as possible as Color 1 is a tad darker from start than Normal
and maybe using the siple settings for RGB gain rather than the full 10 point gamma, which are extreamly sensative

[kal]

On most digital projectors you shouldn't be adjusting the contrast/brightness. The (usually) default setting of contrast 0 is correct. Any higher and you start to clip whites such that anything lower than 235 (white) becomes the same as white. The light output does not go up as you increase contrast over 0 with digital projectors. If you go lower then all you do lower the light output.

Same with brightness on digital projectors. Usually 0 (default) is the only right setting to create what's considered the colour "black". Any higher and the picture washes out because you're raising the black level. Any lower and you all you do is crush blacks such at above black becomes black. Going lower cannot make the black level darker on a digital projector.

Kal

[kal]

On most digital projectors you shouldn't be adjusting the contrast/brightness. The (usually) default setting of contrast 0 is correct. Any higher and you start to clip whites such that anything lower than 235 (white) becomes the same as white. The light output does not go up as you increase contrast over 0 with digital projectors. If you go lower then all you do lower the light output.

Same with brightness on digital projectors. Usually 0 (default) is the only right setting to create what's considered the colour "black". Any higher and the picture washes out because you're raising the black level. Any lower and you all you do is crush blacks such at above black becomes black. Going lower cannot make the black level darker on a digital projector.

Kal

[wanderer]

Having owned 2 x AE4000 projectors and performed measurements and calibrations using the 2 point in the PJ, 10 point in the PJ and Radiance Mini with 2 point, 10 point and 3D Luts here is what I can tell you I found.

If you do a stock default measurement - say Cinema 1 - you'll see it tracks OK until the 80-90-100 IRE levels. There it has this hockey stick like behavior where it drops down a bit, then raises up at the 100 IRE level gamma wise.

You can correct this a bit with the 2 point in the PJ. That's about as good as the projector is likely to look at this point. You can go further with the 10 point in the PJ, and you'll likely find that the various 10% levels - or where you move them to be - do not line up with your 10% IRE level patterns anymore. So you try and adjust the 50% IRE level external pattern image to the 50% adjustment point in the PJ, but that 50% in the PJ menu is really like say 42% of 55% (you don't really know) so it screws up the other adjustment points you've made.

You can go further and just default set the projector and try a Lumagen Radiance on it. Or Autocal it from there with the Radiance. That works - you get a nice ruler flat level from 0 to 100 IRE at whatever gamma level you chose. Great! Except when you view the image on real world material - or ramped test patterns - it doesn't look great at all. If you revert back to the default Cinema 1 or similar with a quick 2 point you'll likely find that looks a whole lot better.

So why is that? I think it goes back to the original hockey stick like default gamma behavior. I think it has that quirk as this PJ in no way is linear with it's behind the scenes internal color\gamma mapping. The designers likely did the best they could with what they had, and out of the box the image isn't too bad as a result. But mess with that and try to remap it to something else, and it falls apart picture quality wise, in my experience anyway.

[HRBO]

Thank you for the time to answer. And your thoughts weight heavy in this matter, Having followed this forum as a interested reader and when i calibrated some plasma 10y ago.

Will probably just run some greyscale runs and use 2point to adjust, cause you can 😀

A final Question as you are familiar with the PJ.

The CMS system? Doesn’t seem perfect for simple sensors. As you get a small box where you see how the colors change. I mean how to be certain that you sensor only capture that small box when you do adjustments, or am I getting this wrong?

[wanderer]

I was using Calman to do my calibrations. For the internal projectors CMS controls, it's been probably 11 years since I last looked at those. From memory it actually adjusted OK but I remember the controls operating in the reverse manner of what you thought they would be. As in you think it should adjust up, but actually you had to adjust down, etc.

Just test it out and see what results you get.

[kal]

[kal]