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Old November 1st, 2006, 04:40 AM   #1
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Blue Screening soft edges in After Effects

Can someone point me to a good tutorial about how to blue screen soft edges in After Effects 7 Pro using only included plug-ins?
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Old November 1st, 2006, 08:33 AM   #2
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Keylight

The best I can tell you is to use Keylight. You need to install the extra programs that come on the first disk of the Production Studio, or the install disk for AE7 Pro. As I recall, it is a separate installation.
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Old November 1st, 2006, 09:27 AM   #3
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Thanx for the input. I’m trying to get strands of hair and motion blur to have an alpha less then 255 but more then 0. Is this just something that DV cant do because of the low resolution and color timing?
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Old November 3rd, 2006, 02:16 PM   #4
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It can be doable, but ... well ... tricky.
Any chance you can upload a second or two of raw video as an example.
(if needed, you can email or pm me and I'll setup an FTP upload site for you)
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Old November 3rd, 2006, 02:47 PM   #5
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I donít really have any videos I can show you right now. Iím preparing to shoot a Green/Blue Screen short just for fun and I donít want everyone to have a big blurry matte line around them. Iíve never been happy with my mattes in the past because the soft edges are always keyed away. I saw that they have done it in Star Wars and in Sin City, but I know both of those movies we shot on uncompressed HD. I assume that the 5:1 compressed nature of DV makes it a problem. Any help I can get would be great.
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Old November 3rd, 2006, 06:22 PM   #6
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Yeah, DV introduces challenges, but there are ways to work around it.

For starters, try to select your screen color and SUBJECT color carefully.
The formula for easiest key is dark subjects in front of a green screen. Dark hair, skin and clothing.
If you have to work with subjects that have fair skin, blond hair and/or light clothing, use a blue screen instead. MUCH easier and cleaner to key than blond on green.
Avoid mixing bright and dark colors in you're subjects where at all possible.

Once you know the base color of your screen, get some paint sample cards from the paint store, setup your camera and lights (setting the camera to manual white balance and calibrating to some kind of white or gray reference that you will use to calibrate for all your shoots) and shoot video of the cards.
Review the RGB values of the various samples in your computer.
The shade that gets you as close to having 255 in one channel and zero in the others is the best color for you. In reality, you'll likely end up with something in the 200's for your screen color, and a value in the 20's for the other two channels.
Use your selected color as reference if you shop for a cloth background, or have the paint store mix up some paint to match so you can paint your screen.

Light the screen as evenly as possible. Avoid shadows and bright spots.
Avoid using halogen worklights for the screen.

Set your camera to manual mode.
Manually calibrate white balance to the same reference for every shoot.
You'll generally be best to have your sharpening value set as low as possible, though some cameras do perform a touch better just above the min.
Also deactivate and digital zoom or stabilization effects.

Since you have AE Pro, install Keylight (comes on the AE disc, but does not install automatically) study the manual and experiment with it .... a lot.
Don't stop at just playing with the basic keying sliders.
Dig into all the sub parameters, including color correction.
There's a lot of power here.

When you get a chance ... pick up Digital Compositing for Film and Video, by Steve Wright. LOADS of in depth information, tricks and tips for digital compositing.

If you focus on shooting good plates to start with, you'll be able to get lots of help and support for the post work by asking lots of questions on boards like this as you go. If you shoot sloppy to start with, there's very little anyone can do to help you get clean composits.

Good luck
Have fun.
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Old November 4th, 2006, 04:14 AM   #7
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Thanx for the help. Iím not a noob at blue/green screen but thanx for the instructions on setting it up. I use the color wheel to figure out what background to shoot on. More red subject go on green and more orange or tan go on blue, because they are complementary colors. Also cause tan and green have yellow in them, where as blue doesnít. Iíll look into that book and see if it helps out.
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Old November 4th, 2006, 09:11 PM   #8
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Cool.
Keep in mind that not all keyers are based on the old-style color wheel though. Keylight is one example that uses color difference keying which is entirely based on the values in the individual RGB channels, rather than Chroma keying which is more closely tied to the color wheel.

For keyers like this, red keys equally well on blue or green .. assuming your camera doesn't bleed the red values into adjacent pixels. Orange and tan will also key well on green so long as the red value exceeds the green channel value.

The big advantage that the brights on blue and darks on green provides for DV camera users is that you can get sharp keys with the extra data in the full res luma channel ... it's not so much the position on the color wheel that's important, but the luma constrast.
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Old November 5th, 2006, 03:44 AM   #9
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Quote:
Originally Posted by Alan James
Iím preparing to shoot a Green/Blue Screen
When using DV -shoot green screen, never blue !
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Old November 5th, 2006, 06:21 AM   #10
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The "always shoot green for DV" is a common misconception.
"DV usually works best with green" is more accurate.

If you shoot green for a blond or bright colors on DV, you end up with no contrast in the green channel (where most of that hi-res luma data is stored) and have to key on the low res red & blue channels.

By using blue screens with DV for blond and other bright colors, you get LOADS of contrast in the hi res luma signal (shown mostly in the green channel) and can get much better keys.

Obviously green is the way to go if the subject contains any blue, like jeans.
Dark color subjects work great on green screens with DV.
Again, the easiest recipie for DV keying is to shoot dark subjects on a green screen.
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Old November 5th, 2006, 09:20 AM   #11
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Iíve been playing around with keylight and it seems that if I get the background to all have the same value then keylight will automatically make the motion blurs visible. When I keyed a background and there was a shadow in it (couldnít be avoided) it would leave the shadow at a low opacity, which is exactly what I wanted. Let me get ur opinion, is it best to shoot blue/green screen with an HDV camera like the FX1 or a DV camera (I have an XL2). HDV is more compressed but has more pixels. DV is less compressed and has fewer pixels. So as far as I understand they have the same amount of information per frame. Anyways whatís ur opinion.
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Old November 5th, 2006, 09:26 AM   #12
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DV is compressed too, but differently. HDV still has more information.
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Old November 5th, 2006, 04:50 PM   #13
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Its only a nightmare when u compare it to 4:4:4 HD and 35mm. Its not to horrible.
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Old November 23rd, 2006, 05:52 AM   #14
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If your subject doesnt have to move a lot horizontally (walk around) you can try to shoot with the camera in "portrait" position so you will have much more resolution to play with and to hide the artifacts from the key (I tested with an XL2 PAL in 16:9 that gives me 1024 pixels tall image and the result was really good)
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