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Contiguous Color Key

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Kevin KnutsonContiguous Color Key
by on Nov 24, 2009 at 7:23:43 pm

Hi All,

So I have shot some basic interview footage using reflecmedia's chromaflex. Pretty standard blue screen stuff, and it keys just fine. However, the subject is wearing glasses, so the blue LEDs from the chromaflex light ring are being keyed out as well making some wicked looking alpha layer eyes!

Right now I'm working around this by duplicating the layers of interview, and creating a custom mask around the eyes on the lower layer (therefore, the background gets keyed, but the eyes do not). Works fine, but takes way too long since the subjects head moves a lot.

Is there a way (without third party plugins) to make a contiguous key, so only the background is keyed?

I'm running AE CS3, footage shot on EX3 1080 24p.


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Dave LaRondeRe: Contiguous Color Key
by on Nov 24, 2009 at 7:46:14 pm

Sorry, but what you've done already is a pretty effective solution.

If you wanted to get fancier, you could minimize the blue in the glasses by using the mask you've already animated on a separate layer and applying AE's Spill Suppressor effect... perhaps more than one instance. Just stick it UNDER the layer containing the chroma key.

I've always been apprehensive about that Chromaflex gizmo and now I know why: reflective surfaces will kill you. They never discuss that inconvenient detail in the product literature, do they?

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Kevin KnutsonRe: Contiguous Color Key
by on Nov 24, 2009 at 9:48:55 pm

Well sometimes its nice to see my hack fix workarounds arent as hack fix as I thought they were, but still bad news.

The chromaflex performs well, but yeah, definitely a small set back with the reflections. Save hours from lighting, add hours in editing. There's no free lunch.


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Dave LaRondeRe: Contiguous Color Key
by on Nov 24, 2009 at 10:59:20 pm

Oh, and by the way: the motion tracking mentioned elsewhere in this thread is just fine... until the subject turns his head. Then it gets dicey.

Got a subject whose head moves vertically or horizontally in the same 3D plane? You're in like Flynn! Got a subject who moves like a normal human being? You've got your work cut out for you... and you've already done a lot of that work, it sounds like.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Walter SoykaRe: Contiguous Color Key
by on Nov 24, 2009 at 11:53:11 pm

The good news for the tracking in this case is that he's just bringing in a mask of the same footage (albeit with different alpha), so you wouldn't have the same perspective issues as you would if you were trying to track in other footage.

That said, I certainly didn't mean to imply that tracking would be a magic bullet. There will still be plenty of roto to do, but hopefully he will be able to get a decent track and save himself some roto (or have success with Chris's method).

Walter Soyka, Principal & Designer
Keen Live: Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak: Our Blog


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Walter SoykaRe: Contiguous Color Key
by on Nov 24, 2009 at 8:48:37 pm

[Kevin Knutson] "Right now I'm working around this by duplicating the layers of interview, and creating a custom mask around the eyes on the lower layer (therefore, the background gets keyed, but the eyes do not). Works fine, but takes way too long since the subjects head moves a lot. "

You might be able to save a bit of time with motion tracking.

Walter Soyka, Principal & Designer
Keen Live: Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak: Our Blog


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Kevin KnutsonRe: Contiguous Color Key
by on Nov 24, 2009 at 9:55:38 pm

Thank you Walter, this will probably be my best option.

Seems like a tragic oversight. You can easily do a contiguous color select in photoshop, so one would imagine you could in AE as well. Two people in the same cave inventing different wheels.


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Chris WrightRe: Contiguous Color Key
by on Nov 24, 2009 at 9:24:23 pm

There's 3 ways I would do this.

1. motion tracking would be really fast if you set the confidence level to 90% so if he turns,it will break, and you can manually drag it in a few spots.

2. primatte keyer comes with a plugging algorithm that thresholds the size groups of the color being keyed, removing small specks.

3. use my eyeball key script in reverse to alpha out the problem.


http://technicolorsoftware.hostzi.com/


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Kevin KnutsonRe: Contiguous Color Key
by on Nov 24, 2009 at 10:00:54 pm

Thanks Chris,

unfortunately we dont have the $500 for primatte keyer, but good to know its there in the future.

Time to brush up on my motion tracking.


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Chris WrightRe: Contiguous Color Key
by on Nov 24, 2009 at 10:13:49 pm

sorry, I forgot to link to my eyeball keyer project. It works like primatte's plugging but it's free. Just remove the smart blur and use the comp as a track matte. Also, autotrace can be usefull.
http://forums.creativecow.net/readpost/50/857313

http://technicolorsoftware.hostzi.com/


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Ryan HillRe: Contiguous Color Key
by on Nov 25, 2009 at 4:19:06 pm

I've sometimes filled holes from keys by playing with extreme values of matte chokers. Use a big negative choker until the hole is filled in, then a big positive choker to remove it from all the edges.





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Kevin KnutsonRe: Contiguous Color Key
by on Nov 25, 2009 at 10:19:53 pm

So I worked with motion tracking the subject's earring, and applied it to a small matte layer underneath the keyed out footage layer. Seems to work well, and takes dramatically less time than key framing a mask.

Once again, the cow rocks. Thanks for your time and suggestions everyone.

Still seems like a horrible oversight on Adobe's part to not have a contiguous key, considering the technology is present in photoshop already.


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Dave LaRondeRe: Contiguous Color Key
by on Nov 27, 2009 at 4:31:53 pm

[Kevin Knutson] "Still seems like a horrible oversight on Adobe's part to not have a contiguous key, considering the technology is present in photoshop already."

Not exactly. Photoshop is designed primarily for still images. nothing's going to change in them. You can get things looking the way you want a LOT easier.

But in AE, the images can -- and often do -- change 59.94 times every second. Things move. they're NOT the same. Because of the nature of how color is recorded on all but the most expensive cameras, the edge pixels are particularly prone to change. The methods used in Photoshop aren't applicable to AE.

It's not an oversight. It's the nature of electronics and digital motion footage.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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Johan RonströmRe: Contiguous Color Key
by on May 9, 2010 at 4:03:44 pm

I respectfully disagree..

There should be no problem for Adobe to make an effect that works like the magic wand on each frame, with tolerance and a specified color, or the color at a specified position in the frame. Doing that for each frame is already possible in photoshop, and the results, as I have tested on five exported frames, are sufficient for what I was looking for.

There is also the Find Edges effect, that already has the ability to detect edges that could be used for continuous keying.


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Max PintonRe: Contiguous Color Key
by on Aug 14, 2016 at 9:52:19 pm

I realize I'm years late to this thread, but since it still comes up when searching for "contiguous key," I thought I'd mention that the Paint Bucket effect seems like a good solution. You'd fill the background with a different key color, precomp the layer, then use Keylight to key out the paint bucket color to get a contiguous key.

Just tinkering around with a gif I was able to key out a white background without losing some white elements of the subject. There are a few spots that need some additional work. I was thinking I could use a second Paint Bucket effect with a keyframed Fill Point to knock those out.



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Matthew WoodsRe: Contiguous Color Key
by on Aug 15, 2016 at 7:57:41 pm

You don't even need to use a color key or pre-comp for this. Just choose "Stencil Alpha" for your blend mode in the paint bucket effect, then check the "Invert Fill" box. Paint Bucket is an incredibly useful and underrated effect in After Effects. I use it all the time.

-Matt

Check out 9 Slice Scale.
A way to scale graphics while preserving the border and corners.
An FxFactory Plugin for AE, Premiere, Motion and FCP.
http://monadnock.org/9slice/


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