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Gamma procedure

667 Views 5 Replies 4 Participants Last post by techman707, Oct 2, 2006

deronmoped

Discussion Starter · Oct 1, 2006

Has someone written up a gamma procedure? I have read some threads about it, but it's just a missmash of stuff with no one really going over step by step how to set up gamma. Some use their video card drivers, some use TT.

There is alot of stuff going on from setting brightness and contrast to setting up the G2 levels or even on the NEC you can set the White balance.

What would be the best test image to use?

Which is set first?

How do the settings for brightness and contrast interact with the G2 levels or how are those set in relation to each other, what about White balance and these settings.

I looked at Curts site and did not see a procedure for setting Gamma and I checked other places, did find one as it relates to a monitor, not sure if it can be used for PJ's.

Thanks, Deron.

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Gary Murrell

· #2 · Oct 1, 2006

set the gamma to where you can see black details but your blacks are still inky black, this applys very easily to us CRT guys

it's a combo of greyscale, g2's(on CRT), brightness, room decor(if FP) and if you have a gamma adjustment

if you had a colorimeter you could get your curve and alter until you get it where you wanted

Gamma is a tricky little guy for sure

-Gary

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tse

· #3 · Oct 1, 2006

First thing that you will need is a properly set-up projector. If you don't have that you are wasting your time. The cut-offs (G-2) need to be right so dim gray content is gray. The drives need to be set right so white is white.

Ok, now that you have that, decide on the light level that you want. 7 foot lamberts is watchable, more is better if you like it brighter.

Get a test pattern that has a white square in the middle of a black field. The area of the white square should be 10-20% of the total screen area.

Input the test pattern at 0% amplitude and adjust projector bright control for just black. Any increase in the bright control begins to light up the screen.

Change the test pattern to 100% amplitude and adjust contrast control for the desired light output.

Now change test pattern amplitude to fractions of 100% and adjust gamma so the light equals the percent of amplitude. 25% amplitude gives 25% of the desired light output. And so on.

That's for linear response. Usually things look better with the lower (

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techman707

· #4 · Oct 1, 2006

Deron,

Are you using an HTPC (or a Moped

) connected to your projector? If you are, there are a couple of programs for the PC that make setting gamma just a simple matter of adjusting a pattern until it appears to disappear. Naturally, you want to have enough FL to get a good picture, as TSE pointed out, or you're just wasting your time.

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deronmoped

Discussion Starter · #5 · Oct 2, 2006

Great, thanks Scott. Looks like some more fun tweaking. The image looks killer right now, if I can get it any better

I just got done watching 8 Mile, great movie with all kinds of bitchen blacks.

Moped power PJ, 150 MPG (movies per gallon), cool.

Bruce, thanks, I ran into one of those programs and bookmarked it. Was not sure if it would work for a PJ, going to have to try it out.

Should the gamma adjustment procedure be added to Curt's site?

Deron.

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techman707

· #6 · Oct 2, 2006

Quote:

Originally Posted by deronmoped
Bruce, thanks, I ran into one of those programs and bookmarked it. Was not sure if it would work for a PJ, going to have to try it out.

Should the gamma adjustment procedure be added to Curt's site?

Deron.

Shhhhh! it was supposed to be a secret, now every one knows.

It was meant for Moped riders only.

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