Film-Tech Forum ARCHIVE: Gamma setting for "alternative content"

This is topic Gamma setting for "alternative content" in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Steve Guttag (Member # 268) on 10-03-2010, 05:15 PM:

An interesting question has been posed on another site regarding the gamma setting of DCinema projectors when running NON-DCinema content.

The Gamma for DCinema content, as defined in DCI spec is 2.6

However, that is not the case for HDTV or other non-DCinema content. It is typically 2.2 - 2.35. Failure to have the proper Gamma will result in either lost black detail or washed out images.

This is presuming too that one properly sets their color space too.

So how are you people setting up your DCinema projectors when running non-DCinema content?

Steve

Posted by Daniel Morez (Member # 5787) on 10-08-2010, 04:14 PM:

2.2 has worked worked well enough when our client wants to view non reference slide shows or a power point from their laptop's DVI out. As you stated, because of all the variables within laptops graphics and OS settings we always make it clear to the client that the projected image may not be an exact or correct representation of their content, especially with regards to the black levels.

(btw, 1st post YAY!)

Posted by System Notices (Member # 2357) on 02-20-2012, 01:15 AM:

It has been 499 days since the last post.

Posted by Scott Norwood (Member # 30) on 02-20-2012, 01:15 AM:

Bump.

Running HDCAM directly into a series 2 Christie via HD-SDI, using YCbCr 709 colorspace, I was happiest with the "NTSC" gamma setting. I have no idea what this really is or if it is correct, but it makes pretty pictures. Is there any reason not to do this? And what is "NTSC" gamma, anyway?

Posted by Joe Redifer (Member # 3) on 02-20-2012, 02:54 AM:

7.5 IRE for USA and 0.0 for Japan.

Posted by Steve Guttag (Member # 268) on 02-20-2012, 06:30 AM:

The "correct" gamma would be 2.3 - 2.35. I'll see if I can find out what the "NTSC" gamma is. As Joe pointed out...it is probably optimized for SD video with a 7.5IRE lower reference.

Posted by Scott Norwood (Member # 30) on 02-20-2012, 08:46 AM:

quote: Joe Redifer
7.5 IRE for USA and 0.0 for Japan.

How does it know where it is?

Posted by Joe Redifer (Member # 3) on 02-20-2012, 08:55 AM:

It comes with its own GPS.

Posted by Steve Guttag (Member # 268) on 02-20-2012, 10:31 AM:

Ask a silly questions...

It doesn't.

Posted by Alan Gouger (Member # 543) on 02-20-2012, 11:22 AM:

The problem with lower gamma it visually brings out the nasty's ( banding, posturization during fade in/outs, compression artifacts ) in the source. Even if authored for 2.2 the compression used ( including Blu-Ray ) proves not big screen friendly especially if you have a bright projector. For consumers 4k display is the new buzz allowing one to sit closer. I cant see anyone wanting to sit closer to the moving squiggly artifacts, "distracting". Most of this stuff is authored with j6p in mind for a 42" plasma. Using a higher gamma can hide some this but be careful to not crush detail. I find 2.4 is a fair compromise.