Return-Path: Received: from atl4mhob10.myregisteredsite.com ([209.17.115.48] verified) by media-motion.tv (CommuniGate Pro SMTP 4.2.10) with ESMTP id 5044360 for AE-List@media-motion.tv; Sat, 20 Apr 2013 07:59:40 +0200 Received: from mail.hostingplatform.com ([10.30.71.207]) by atl4mhob10.myregisteredsite.com (8.14.4/8.14.4) with ESMTP id r3K67qts003682 for ; Sat, 20 Apr 2013 02:07:52 -0400 Received: (qmail 2784 invoked by uid 0); 20 Apr 2013 06:07:51 -0000 Received: from unknown (HELO ?192.168.0.7?) (chris@chriszwar.com@60.225.197.206) by 0 with ESMTPA; 20 Apr 2013 06:07:51 -0000 From: Chris Zwar Content-Type: multipart/alternative; boundary="Apple-Mail=_47D7B57F-4CD3-476D-8462-4939BA230B3D" Message-Id: Mime-Version: 1.0 (Mac OS X Mail 6.3 \(1503\)) Subject: Re: [AE] Keying and other things Date: Sat, 20 Apr 2013 16:07:49 +1000 References: To: "After Effects Mail List" In-Reply-To: X-Mailer: Apple Mail (2.1503) --Apple-Mail=_47D7B57F-4CD3-476D-8462-4939BA230B3D Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=windows-1252 You basically learn from difficult keys, sometimes there's no easy = solution. One thing to look at is pre-processing your footage before = keying. In many cases noise reduction or grain removal can have = dramatic results on your output. The standard AE grain removal plugin = can be bit coarse when it comes to temporal smoothing, but it's better = than nothing. Grain / noise management is really important for good = clean keys. Apart from grain removal, for keylight you can try doing a hue shift to = increase the difference between the green channel and the red and blue = channels. This will give you a different result, but not necessarily a = better result. Keylight is a difference keyer - it looks at the = difference between the green channel and the red / blue channels. = Greenscreens are very rarely a purely 'digital' green - most greens have = a lot of red in them and are actually quite yellow. Apply the hue / sat = filter, and then apply the levels filter so you get a histogram. You = should be able to see three clear peaks in the histogram for red / green = / blue. Adjusting the hue will move these peaks, and shifting the hue = by a few degrees will move the red peak further away from the green, and = start moving the blue closer (or vice versa). Find a value that puts = the most difference between the green and the red/blue channels. In = SOME cases this will give you a better result with fine edge detail such = as hair. I've done a few side-by-side comparisons with hue shifted = green screens and they've been better about half the time. If you are = hue-shifting by a large amount you'll probably want to use the keyed = layer as an alpha matte for the original source. -Chris On 20/04/2013, at 2:10 PM, Jonathan wrote: > Good day to all. >=20 > I've been using Keylight to do some green screen work and, basically = starting from scratch, went through a number of tutorials, including = three from The Foundry for Nuke but which are applicable to After = Effects. All the tutorials, however, are general and don't deal much = with pulling difficult keys, such as shots of little girls with frizzy = hair. I've gone about as far as I can go with what I've learned and my = results aren't very good: the hair in the transparent areas chatters = like crazy. Fortunately I'm scaling from full HD down to 720 X 405 so = some of the noise becomes a minor problem. However, there is one shot = that is really not acceptable. >=20 > I'm using a pre-comped layer to create a matte for the same layer = below it, trying everything I can but still missing it. I realize this = may be difficult to answer without seeing the project, but any tips = anyone might want to offer would be much appreciated. (CS 6, Keylight = 1.2) Thanks in advance. >=20 > Jonathan >=20 >=20 > JONATHAN PENZNER > VIDEO EDITING =95 MOTION GRAPHICS =95 DESIGN >=20 > | STUDIO 626 345-0285 | > | CELL 818 321-2890 | >=20 > sureal@charter.net --Apple-Mail=_47D7B57F-4CD3-476D-8462-4939BA230B3D Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=windows-1252 You = basically learn from difficult keys, sometimes there's no easy solution. =  One thing to look at is pre-processing your footage before keying. =  In many cases noise reduction or grain removal can have dramatic = results on your output.  The standard AE grain removal plugin can = be bit coarse when it comes to temporal smoothing, but it's better than = nothing.  Grain / noise management is really important for good = clean keys.

Apart from grain removal, for keylight = you can try doing a hue shift to increase the difference between the = green channel and the red and blue channels.  This will give you a = different result, but not necessarily a better result.  Keylight is = a difference keyer - it looks at the difference between the green = channel and the red / blue channels.  Greenscreens are very rarely = a purely 'digital' green - most greens have a lot of red in them and are = actually quite yellow.  Apply the hue / sat filter, and then apply = the levels filter so you get a histogram.  You should be able to = see three clear peaks in the histogram for red / green / blue. =  Adjusting the hue will move these peaks, and shifting the hue by a = few degrees will move the red peak further away from the green, and = start moving the blue closer (or vice versa).  Find a value that = puts the most difference between the green and the red/blue channels. =  In SOME cases this will give you a better result with fine edge = detail such as hair.  I've done a few side-by-side comparisons with = hue shifted green screens and they've been better about half the time. =  If you are hue-shifting by a large amount you'll probably want to = use the keyed layer as an alpha matte for the original = source.

-Chris

On = 20/04/2013, at 2:10 PM, Jonathan <sureal@charter.net> = wrote:

Good day to = all.

I've been using Keylight to do some green screen = work and, basically starting from scratch, went through a number of = tutorials, including three from The Foundry for Nuke but which are = applicable to After Effects. All the tutorials, however, are general and = don't deal much with pulling difficult keys, such as shots of little = girls with frizzy hair. I've gone about as far as I can go with what = I've learned and my results aren't very good: the hair in the = transparent areas chatters like crazy. Fortunately I'm scaling from full = HD down to 720 X 405 so some of the noise becomes a minor problem. = However, there is one shot that is really not = acceptable.

I'm using a pre-comped layer to = create a matte for the same layer below it, trying everything I can but = still missing it. I realize this may be difficult to answer without = seeing the project, but any tips anyone might want to offer would be = much appreciated. (CS 6, Keylight 1.2) Thanks in = advance.

Jonathan


VIDEO EDITING =95 MOTION = GRAPHICS =95 DESIGN

| STUDIO      626 = 345-0285 |
 CELL   =         818 = 321-2890 |

=

= --Apple-Mail=_47D7B57F-4CD3-476D-8462-4939BA230B3D--