Clever use of Photoshop channel

The AB channel ignores the light and shade to play its advantage again in our last flower image. The bright flowers and backgrounds in Figure 9-6a are very different, making it seem as if you can create a mask with a red channel.

Figure 9-6a

However, this assumption was eradicated by the stone texture in the background. If there are no millions of white spots behind it, it is easy to find white flowers in the red channel.

Figure 9-6b Red Channel

A channel does not become abnormal due to white or black spots in the gray area. They are all neutral colors and their values are 0 a. They provide a very smooth background for tulips, which are great positive in a channel.

Figure 9-6b A channel

If the color of the detail is different from the objects around it (unlike figure 9-6), when you create a mask, very good detail often facilitates the use of the AB channel. Photographs taken in the spinning frame (shown in figure 9-7) cause problems with the creation of a selection.

Figure 9-7

Suppose we want to choose a face, a lip, a blue background, or a hair. For any one of them, the most likely RGB source will be the red channel. In lab it should be B channel, because the face value is positive, the yellow component is more blue, and the background value is a great negative.

Almost all conceivable selections include grids, because when we make any adjustments to the objects that follow, the grid color needs to change.

Figure 9-8a B-Channel under Lab

In Figure 9-8a, the grid gets too many background colors, and B channels can hardly see it. However, in the red channel shown in Figure 9-8b, the grid cannot be eliminated without a considerable blur operation. So lab is also the best place to start masking.

Figure 9-8b The red channel under RGB

Category:

• PS Image Processing