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How to key out every other color

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Matthew Rideout
How to key out every other color
on Mar 15, 2010 at 9:10:56 pm

I am having trouble keying out every other color in a scene.

I want fire to track my hand (with particle playground) and am using colorleave, threshold, and lumakey to isolate my hand... However its not working that well in all situations

I want to make everything black except for the skin color on my hand... I am using the pen tool to track a box around my hand to apply the effect to so that it wont pick up on my face, etc...

Once I have the skin color on my hand isolated, I will use lumakey and layer exploder (with particle playground)to make the particles come out of my hand..

So far this is only working well for me if the background is darker than my hand... (so i guess colorleave isn't helping much at this point)

Anyone know how to help?

Thanks!


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Dave LaRonde
Re: How to key out every other color
on Mar 15, 2010 at 9:33:59 pm

[Matthew Rideout] "Anyone know how to help? "

Yeah -- think about what you're doing rather than shooting first and thinking to yourself, "I bet I can get something to work."

Or you might just want to describe in detail what you're trying to accomplish, and get some pointers from the group.

And when I say "in detail", I mean it.

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


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Matthew Rideout
Re: How to key out every other color
on Mar 15, 2010 at 10:15:50 pm

Ok I accomplished what I am going for.. but i'll go over it in detail here in case someone in the future stumbles across this thread.

I watched this video on how to create fire
http://library.creativecow.net/articles/drozda_jerzy/ParticlePlayground.php

I wanted it to look like the fire was coming out of my hands, however the exact method of tracking my hands wouldn't work the same as in the tutorial. In the tutorial the hands were the only thing moving so they used an effects to only track motion and attach the particles from particle playground to the motion.


Since there was a lot of stuff moving in my scene, I needed to be able to track the fire (particles) to the skin color on my hand. In order to do this I needed to do the following

1.) Create a mask to track my hand in a small box as to not capture skin colors from anything else

2.) Isolate this skin color and make everything else black

3.) Use LumaKey to key out all darkness thus leaving only my hand and everything else transparent

4.) In the particle playground effect I needed to use "Layer Explode" to make the particles explode out of my layer, the layer I used lumakey to key out everything except my hand... Thus the particles explode out of my hand


The way I solved this:

I used the "Change Color" effect to crank up the lightness on my hand's skin color making it pure white. I then used Threshold to blacken everything else and leave just my hand pure white on a black background (threshold is like a 100% contrast effect which only allows pure black and white to show)

Then use lumakey to key out the black and leave the white as a layer for the particles to explode out of

Then overlay this composition of particles coming out of a floating hand on top of my source footage

The "change color" effect which allowed me to crank my skin color up to pure white is what saved me here and allowed lumakey to work properly.

Here is an example video of what I was trying to do, its buggy but i was just trying to learn the concept for a project im working on... ( i was initially going to be trying to throw fire but I haven't gotten that far yet... Maybe I'll track a tennis ball or something!)


Original Video - More videos at TinyPic


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Darby Edelen
Re: How to key out every other color
on Mar 16, 2010 at 2:34:33 am

Next time see how few color correction filters you need to accomplish this.

I bet you could've gotten it with Color Correction > Channel Mixer (set to 'Monochrome') alone... maybe a Color Correction > Levels for good measure!

Darby Edelen


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Darby Edelen
Re: How to key out every other color
on Mar 16, 2010 at 2:32:42 am

[Matthew Rideout] "So far this is only working well for me if the background is darker than my hand... (so i guess colorleave isn't helping much at this point)"

What background did you shoot your footage against? Have you tried using standard color correction effects to darken the background and brighten your hand?

Darby Edelen


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Matthew Rideout
Re: How to key out every other color
on Mar 17, 2010 at 1:16:16 pm

Oh it looks like tinypic lost my video, here I'll re-post it. I was going to be trying to "throw" fire with it initially and its a little buggy but here it is.




Darby, no I haven't tried that yet. This is just a "testing background". This isn't my actual project, I just shot this footage with the intention of trying to attach fire to my hand to learn the concept in general. I am very new to after effects.

Hopefully this footage will give you guys a better idea of what I'm working with. Here's a step by step of the filters I applied. Looking back it appears that "color leave" may have been unnecessary, but i don't know how I could accomplish this with any less filters



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