Quickly extract fire (and other translucent things) from a background.

[K]

So for work the other day I needed to extract flames from a background and place them on a new background. The problem with the traditional cutting methods, is that the fire is translucent. This leads to obvious problems around the edges. Here's what would happen if I tried to cut the fire with the pen tool and place it on the blue background...

It's only quick, but you can see it won't work.

A better way is to flip over to your channels menu.

Once there, click on whichever channel is the brightest (In the case of fire, it'll be red) the image will go black and white, showing you the density of reds. Simply Command+Click (Ctrl+Click in windows) on the little preview of your image next to the word red, and this loads it as a selection.

Then click the rgb icon and Command+C (Ctrrl+C) to copy it.

What you've done, is copied everything within the red boundries, from the entire colour spectrum.

Then simply flip back to your layers menu and paste.

Play around with blending modes and a soft eraser to tidy it up.

[Lord Nibbler]

I know this is old, but I had to extract some clouds from a background and this technique worked a treat. Cheers Keith.

[K]

Thanks for that. Glad it worked out for you.

With a few tweaks, you can also use it to extract fluffy hair as well.

[New Damage]

Just used it to make a flaming crowbar (in joke). It was a quick job so didn't really make it to look fantastically pretty.

Edited January 5, 2010 by TheModernWay

[K]

Looks good man. Glad this tip is helping people.