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Alpha Channel

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Alpha Channel cedric 13 Apr 01:47
  Alpha Channel Malcolm Tredinnick 13 Apr 02:12
  Alpha Channel David Marrs 13 Apr 16:57
   Alpha Channel Jeffrey Brent McBeth 13 Apr 17:13
    Alpha Channel David Marrs 13 Apr 17:34
cedric
2005-04-13 01:47:48 UTC (almost 20 years ago)

Alpha Channel

I wonder why, when Opening or creating a document, there are only 3 color channel and then, when creatin a layer, the alpha is coming. What this stand for ?

Cedric

Malcolm Tredinnick
2005-04-13 02:12:19 UTC (almost 20 years ago)

Alpha Channel

On Wed, 2005-04-13 at 01:47 +0200, cedric wrote:

I wonder why, when Opening or creating a document, there are only 3 color channel and then, when creatin a layer, the alpha is coming. What this stand for ?

The default setting for a new document is the RGB colorspace with the document filled with the background color; no transparency is needed. When you add a layer, if you change nothing, the layer will be transparent, so an alpha channel is required at that point and one will be added.

You can set up a new document to have the background filled with "transparency" (under the advanced options tab in the new image dialog box) and then you will have an alpha channel from the start. However, if you create a new layer filled with the background or foreground color, that will still add an alpha channel if you do not have one in the image, because there are always transparency options available for layers.

Cheers,
Malcolm

David Marrs
2005-04-13 16:57:56 UTC (almost 20 years ago)

Alpha Channel

cedric wrote:

I wonder why, when Opening or creating a document, there are only 3 color channel and then, when creatin a layer, the alpha is coming. What this stand for ?

Cedric

The bottom layer cannot be transparent, as far as I'm aware, so it does not have an alpha channel associated with it. You can still export transparent gifs and pngs though.

Jeffrey Brent McBeth
2005-04-13 17:13:16 UTC (almost 20 years ago)

Alpha Channel

On Wed, Apr 13, 2005 at 03:57:56PM +0100, David Marrs wrote:

cedric wrote:

I wonder why, when Opening or creating a document, there are only 3 color channel and then, when creatin a layer, the alpha is coming. What this stand for ?

Cedric

The bottom layer cannot be transparent, as far as I'm aware, so it does not have an alpha channel associated with it. You can still export transparent gifs and pngs though.

Err, unless I am misunderstanding you, you are wrong. Bottom layers can most definitely be transparent. As noted previously in response to this question, when you create a new image, what you fill the base layer with changes whether or not it has an alpha channel. At any point, you can add an alpha channel by going to:

Layer -> Transparency -> Add Alpha Channel

At any point, you can remove an alpha channel by flattening the layer.

Jeff

David Marrs
2005-04-13 17:34:32 UTC (almost 20 years ago)

Alpha Channel

Jeffrey Brent McBeth wrote:

On Wed, Apr 13, 2005 at 03:57:56PM +0100, David Marrs wrote:

cedric wrote:

I wonder why, when Opening or creating a document, there are only 3 color channel and then, when creatin a layer, the alpha is coming. What this stand for ?

Cedric

The bottom layer cannot be transparent, as far as I'm aware, so it does not have an alpha channel associated with it. You can still export transparent gifs and pngs though.

Err, unless I am misunderstanding you, you are wrong.

Yup, sorry. I should know that, having made bottom layers transparent in the past! (wtf?) I don't know where I got that from. Put it down to lack of coffee.