View Full Version : Which tool for an alpha channel

05 May 2003, 05:34 PM
I'm using v7 to make a 3d background image - trees on a landscape - for use as an alpha plane. I need the sky to be black so it will be transparent in the 3d app. I cannot figure out the right tool or settings to use to select the sky only - all those little bits of sky through the trees. Do they have to be selected totally by hand - each little one? Also how do I keep the trees from having a slight visible "halo" around the edge against the sky? Is this an antialiasing issue. A little help here would be sincerely appreciated - thanks, arch

05 May 2003, 06:17 PM
I think your best bet would be use a Channel as your base. My guess would be either Green or Blue.

Copy the channel of choice.
Curve or Level it until it looks like a decent base.
Apply it as a Layer Mask.
Paint in any touches that it needs.
Or give it any other touches that it needs.

See: Replacing a Background ( by Steve.
And: Whispies (

05 May 2003, 02:33 PM
Thank you very much - excellent tutorials. I really appreciate it!

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