What is Alpha Channel

In Graphics, a portion of each pixel's data that is reserved
Transparency information. 32-bit graphics systems contain four channels
-- Three 8-bit channels for red, green, and blue (RGB) and one 8-bit
Alpha channel. The alpha channel is really a mask -- it specifies how
The pixel's colors shoshould be merged with another pixel when the two are
Overlaid, one on top of the other.

Typically, you wouldn't
Define the alpha channel on a pixel-by-pixel basis, but rather per
Object. Different parts of the object wocould have different levels
Transparency depending on how much you wanted the background to show
Through. This allows you to create rectangular objects that appear
If they are irregular in shape -- you define the rectangular edges
Transparent so that the background shows through. This is especially
Important for animation, where the background changes from one frame
The next.

Rendering overlapping objects that include an Alpha value is called alpha blending.

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There are many tutorials and articles on how to apply the alpha channel. However, we have hardly seen the alpha channel.

To open an image (.jpg as an example) in ps, three channels are automatically generated: Red, green, and blue. These three channels are called color channels.

Create a selection area on the image, and then use the: Select/store selection area command to save the selection.

When you enter the channel panel, you will find an extra channel. This is the alpha channel.

It seems that the alpha channel is used to "store constituency. So what is the method used to implement the alpha channel "Storage selection?

Many may think that the alpha channel records the location information of the constituency to save the constituency. However, this understanding is one-sided.

The alpha channel not only records the location information of the selected area, but also records the "Transparency" of the selected area pixels to save the selected area. A little abstract, right? But this is true.

The alpha channel does seem invisible and invisible. Because of its special functions.

On the image, we use the selection tool to create a selection area, save the selection area, and then look at the Alpha Channel. You will find that the alpha channel chart has changed. Why? This is because the selected area is down.

Do
The purpose of the selection is to "Blur" the selection edge. If the alpha channel only records the location information of the selected area, how can we achieve "Dizzy? The mechanism used to implement "Vertigo" is:
Based on the operator's settings, a function diagram is automatically generated on the Alpha Channel diagram. In this example, the gray scale values 0-256 correspond to 0%-100% (transparency), respectively. Transparency
100% (corresponding to 255 gray, white) indicates that the pixel is completely displayed, and when the transparency is 0% (corresponding to 0 gray, black) indicates that the pixel is completely not displayed, other transparency 1%-99% will be performed proportionally"
Proportional Transparent Display ". When there is no feathers, only 225 white and 0 black are used in the function diagram. This role chart is the "Transparency" information recorded in the alpha channel.

After you execute the select/load selection command on the Alpha Channel of the image, and then on the layer, CTRL + J, you will see an image with the edges indicated on the new layer.

Therefore, you can use a paint brush, 255 white to smear the desired area, and 0 black to smear the unwanted area on the new alpha channel diagram, partial transparent areas are required to be painted in gray with different gray scales. The degree of transparency is determined by the gray scale you choose.

Run the select/load selection command on the Alpha Channel of the image. Then, on the layer, CTRL + J, you will see it on the new layer, all the performances of the alpha channel diagram you designed based on the principle of transparency.

After understanding this principle, you will understand that the alpha channel is not difficult to understand.