Words the mystery of the solution channel

The channel, which we often use only alpha channels, has always been considered a higher threshold between the introduction and the Advanced level of Photoshop. For a long time, many so-called textbooks have deified it in obscure language, which makes many beginners puzzled.

In fact, we do not have to channel the formal definition of what the channel algorithm is what, we are not developing software, pipe it to do what. We just need to understand what kind of impact the channel has on us.

In this chapter, you just need to understand what a mask is and what you call a constituency. And what the hell is a mask? Forget it, you understand that: outside the constituency is the mask. The selection is operable, and outside the selection is a mask, protected and temporarily unable to operate.

At the same time, I do not want to explain any formal concepts, the following with a number of illustrations to demonstrate, we can feel that the line.

Figure 1

First from the RGB channel, an RGB image, there are red (red), green (green), Blue (blue) three channels, three channels, integrated into an RGB channel. You can understand that: Red+green+blue=rgb, although in fact it is not such a simple algorithm, however, it is no use to know.

You might as well a new RGB file, white, and then use pure red, green, blue three colors to draw a rectangle, after painting, and then look at the channels panel, you will magically find that these three channels are only two rectangles, and each is different. (as shown in Figure 1)

Why, then? You see, in the red channel, both the green and the blue rectangles are represented in black chunks, while the red rectangles are missing. Hey, it is not missing, but in white, in the case of white, of course, you can't see.

The other two channels are interpreted similarly.

Now in a simple way to answer it, the red channel can be red, and blue and green, such as red pigment, are blocked. It's kind of like sunglasses to block ultraviolet light. A region that is passed, understood as a selection, an area that cannot be passed, such as a black block in a channel, or a mask.

You try to hold down the CTRL key, and then click on the red channel to see the selection, which is the other area except the blue and green rectangles.

Figure 2

Figure 3

Look at the alpha channel again, but the truth is the same. In the alpha channel, White represents the selection, and black is the mask. As shown in Figure 2, the white area is actually the selection as shown in Figure 3.

Figure 4

Figure 5

We will figure 2 with the appropriate Gaussian blur, the effect shown in Figure 4, days, this time is not black and white, because the black and white mixed together, there is no clear boundary.

Yes, this time the constituency also has no obvious boundary, you see, Figure 5 is to fill the selection with red, and found that the effect is very feather, which is the result of the boundary is not clear.

When it comes to the point, because we use the rectangular marquee, lasso, and other marquee tools, you can't drag and choose a very complex selection, but in the channel, you can do the filter operation/tool operation so that you can make strange, omnipotent selections. This is the charm of the channel.

By the way, another related concept, is quick Mask (fast mask), in fact, can be regarded as temporary access.

I, do not say more, this article for beginners, so not to speak too deep, slowly understand it.

Summary

According to this idea, a good thought, I believe that not two hours, you can understand the channel.