Making an alpha channel in Photoshop

Discussion in 'Mapping Questions & Discussion' started by The Asylum, Jan 11, 2010.

  1. The Asylum

    aa The Asylum

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    The poster/overlay tutorial tells you what to use as an alpha channel.... just not how to set one.

    But anyway, it's like this:

    Layer 1 is an image. Layer 2 is black, obviously what I want to set as a transparent alpha channel. Now what? :confused:
     
  2. YM

    aa YM LVL100 YM

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    The "channels" tab

    Create a normal black and white (with shades of grey for semi-transparent) (black is fully transparent) layer that represents the transparency of your image. if you use several layers to get the right transparency merge them all into one b/w layer and copy it all. (don't cut, you need to have a layer with stuff in it selected)
    Then hit the channels tab next to the layers tab, hit the usual "new layer" button (only it's adding a new channel) and it should make a new channel called alpha 1
    select just alpha 1 and paste your b/w image in.
    Go back to layers, hide the b/w stuff so just your poster is visible (you need to re-enable the RGB channels to see stuff) then simply hit save as vtf.
     
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  3. The Asylum

    aa The Asylum

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    Don't take this the wrong way Youme, but..... I want to have your babies.
     
  4. honeymustard

    honeymustard L9: Fashionable Member

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    I always seem to get a slight white trim to mine, regardless of what I do.
     
  5. Altaco

    Altaco L7: Fancy Member

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    What you want to do is duplicate your image, place it on a layer below, and smudge the bottom layer outward a bit. Or just use the layer settings to make the alpha mask slightly smaller.
     
  6. YM

    aa YM LVL100 YM

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    make it float above a layer that is the same colour as thevery edge of the poster, that way the white trim will still be there, but be exactly the same colour as the poster itself, making it invisible
     
  7. Pocket

    aa Pocket func_croc

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    You don't happen to (a) be trying to resize the image while it's still in multiple layers, or (b) have antialiasing turned on in the paint bucket or selection tool, do you?