Cleaning Up an Alpha Channel - Photoshop vs AE
by Alex Kuzelicki
on
Apr 28, 2008 at 4:27:29 am
Hi,
I just saw a great Photoshop tutorial where you can 'clean up' an Alpha Channel with the Burn tool. Basically, you set it for the shadows with its Exposure way down, and you can brush over a b&w image to make grey/white areas black, without affecting the white areas very much at all. This is fantastic for getting at hair and other fine details that would be really hard to get a good Alpha Channel for.
My question "Is there a way to do a similar thing right in After Effects?" I know you can use Paint tools to paint on the Alpha Channel of a clip but is there something equivalent to Photoshop's Burn tool - that gradually works in black areas without really affecting white areas. Would be a great addition to those of us dealing with difficult keying work.
Re: Cleaning Up an Alpha Channel - Photoshop vs AE by Dave LaRonde on Apr 28, 2008 at 4:13:40 pm
[Alex Kuzelicki]"I just saw a great Photoshop tutorial where you can 'clean up' an Alpha Channel with the Burn tool.... This is fantastic for getting at hair and other fine details that would be really hard to get a good Alpha Channel for."
All I can think of is the phrase, "30 pictures every second".
That would be my first guess why this particular aspect of Photoshop isn't incorporated into AE. There may be other reasons as well.
If it COULD be integrated into video -- a comparatively low-resolution image source, even in HD -- to get really good keys, you'd think a lot of people would be doing it already.
Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA
Re: Cleaning Up an Alpha Channel - Photoshop vs AE by Darby Edelen on Apr 29, 2008 at 2:18:50 am
You could burn an alpha channel with an alpha channel... if that makes sense.
Shift the channels of two instances of the same footage to Alpha only, then set the top layer to one of the darken modes: Multiply, Linear Burn, etc. Or you could use one of the overlay modes to boost contrast (darken the darks, brighten the brights): Overlay, Soft Light, Hard Light, etc. You can change the opacity or alter the levels of the top layer to vary the effect.
It's not as "hands on" but it could help in certain scenarios.
Darby Edelen Lead Designer Left Coast Digital Santa Cruz, CA
