Unity uses straight alpha blending. Hence, you need to expand the color layers... The alpha channel in Unity will be read from the first alpha channel in the Photoshop file.
Unity使用直接alpha blending(alpha通道混合)，因此，你需要扩展颜色层…，在Unity中的alpha通道将从Photoshop文件的第一个alpha通道读取。
Setting Up 设置
Before doing this, install these alpha utility photoshop actions: AlphaUtility.atn.zip
开始动手之前，需要安装AlphaUtility.atn.zip。
After installing, your Action Palette should contain a folder called AlphaUtility:
安装之后，动作面板中应该包含一个AlphaUtility文件夹：
Getting Alpha Right 获取正确的Alpha
Let's assume you have your alpha texture on a transparent layer inside photoshop. Something like this:
假设你的photoshop中在透明层上有一个alpha纹理，就像这样：
Duplicate the layer 复制该层
Select the lowest layer. This will be source for the dilation of the background.
选择最底的一层，这将是背景扩张的源。
Select Layer->Matting->Defringe and apply with the default properties
选择Layer->Matting->Defringe并使用默认的属性
Run the "Dilate Many" action a couple of times. This will expand the background into a new layer.
运行"Dilate Many"动作多次，他将扩展背景到一个新的层。
Select all the dilation layers and merge them with Command-E
选择所有扩张的层并使用Command-E（Ctrl-E）命令合并图层。
Create a solid color layer at the bottom of your image stack. This should match the general color of your document (in this case, greenish).
在图像堆栈的底部创建一个纯色层，这个应该与文档的大部分颜色匹配(在这里是浅绿色)。
Now we need to copy the transparency into the alpha layer.
现在我们需要复制透明度到alpha层中。
Set the selection to be the contents of your main layer by Command-clicking on it in the Layer Palette.
在图层面板，选择你的主层内容。
Switch to the channels palette. 切换到通道面板
Create a new channel from the transparency. 从透明度创建一个新的通道
Save your PSD file - you are now ready to go.
保存PSD文件，现在已经准备好。
