CurtPalme.com Home Theater Forum

[opv]

Hi,
Can anyone here give their values for 11 or 21 point gamma correction with a 9" CRT?
I only need the luma values.
I'm aware that the optimal settings in my room may be different but I just need reference values to start with.
Thanks,
Or

[napos]

Or,

Before you start messing with the Lumagen gamma correction, make sure your G2 settings are correct. If you are using an external Moome HDMI box or an HD Fury make sure the colorspace is set properly, meaning that the external box is not clipping any information.
Having done that, if you need just a little more gamma push to show low IRE detail, try adjusting the main gamma control on the Lumagen from 1.0 to 0.95 or so.
See if that brings out the detail you wanted. The good thing about the main gamma control is that adjustment is linear, so you will not see any Low IRE scenes to appear to be washed out.
You could set IRE 2.0 to a setting of 3.0 IRE in the 21 or 11 point gamma adjustment, but I have found that because you abruptly raise the luminance of a low IRE point there is usually a washed out appearance in certain scenes. You could try adjusting IRE 2.5 to a setting of 3.5 to see if that helps.

[opv]

napos,
Thanks for the reply.
My G2 is well adjusted, and my projector is grayscale calibrated.
The reason I got the Lumagen is that I never got a perfect result with the Moome Gamma correction.
I want to get perfect linear gamma.
I guess I'll calibrate IRE 10:10:100 using the sensor, but as you know the lower IRE values are much trickier.
That's why I want the Luma table from someone who already went through the process.

Thanks again.

[napos]

Try using the general gamma control first because it is linear. Since your G2 levels are correct and you have a the grayscale calibrated, you should not need a lot of adjustment if your video levels are set correctly. Since the Radiance has a lot of options, make sure that your input AND output levels match. I am using Componenrt (YcPbr) 422 video levels on both input and output. The Moome box will accept the signal correctly. If not, there is an option to set it on the remote control (I think you need to press 4 or 7). Also on the Moome VIM card there is an option for the RBG range (0-255 or Super White or 16-235). The buttons that change those are "a", "b" and "c" respectively. If the same option exists on the Moome box, make sure this setting is also correct. If you have set input and output levels on the Lumagen as Video (Component 422 is always video level), then you should select "c" on the Moome box.
I hope this gives you some more things to check out before you start calibrating with a light meter.

Nicholas

[opv]

napos,
Thanks again.
You gave me allot of things to check before actual calibration.

[napos]

Let me know how it goes. When you do get the correct combination of settings, the image just pops out and looks punchy and contrasty. There is no more haze over low lit scenes. Combine that with the contrast ration that a 9" LC CRT can produce and it is as good as it gets!

[opv]

One more question on the way,
Now that I have the option to correct the 3 colors in 21 points, can I avoid defocusing the blue tube and still get accurate colors at low IRE values?

[napos]

You can, but you will drive the blue too hard to do so. The problem with the blue tube is in the high IRE values. Defocusing the blue electronically does not drive it harder and it also becomes brighter. The more focused blue is, the dimmer it is. So, you gain better grayscale and brightness by defocusing blue. Defocus it to the point where high IRE's look neutral and you should be OK. It should not be noticeable in video material that the blue is defocused.