010 Rule Selection Tool

1. The selection tool is used to select the area of ​​the image that needs to be modified. The core of image processing is selection.
2. The selection tools are: regular selection tool group, irregular selection tool group, and quick selection tool group. The corresponding tool location is shown in the figure
   
    
3. Modifications can be made to the selected area, such as painting and adjustment, without affecting the outside of the area, as shown in the figure
   
    
4. Drag within the selection to drag the selection
5. Left-click outside the selection to cancel the selection, ctrl+D to cancel the selection, and to cancel the selection in the selection menu.
6. You can copy the selection area ctrl+J as a new layer, or ctrl+c, ctrl+v to copy as a new layer, or drag with the move tool to move the image in the selection, or hold alt+move tool and drag to copy as a new layer layer.
7. Press and hold the left mouse button on the rule selection tool group, and you can see the rectangular marquee tool, the elliptical marquee tool, the single row marquee tool, and the single column marquee tool in the pop-up box.
8. Click the Rectangular Marquee Tool, hold down shift+left-click and drag to create a square selection area. Press and hold alt + left button to click and drag to create a rectangle tool radially based on the click position. Shift+alt+left click and drag to create a square radially based on the clicked position. Use the Elliptical Marquee Tool in the same way.
9. Both the elliptical marquee tool and the rectangular marquee tool can modify the style and adjust the size style when drawing the marquee, as shown in the figure
   
    
10. The Elliptical Marquee Tool can eliminate aliasing, and both the Elliptical Marquee Tool and the Rectangular Marquee Tool can be feathered, as shown in the figure (5 pixels inside and outside the edge):
    
     
11. For row marquee tool and column marquee tool, if the feathering value is greater than 0, a warning box will appear "Any pixel is not greater than 50% of the selection edge will be invisible", and the selection will not be visible after clicking OK, as shown
    
    in the figure. 
    
      
    Principle: Pixels are not subdivided units. If anti-aliasing or feathering is performed, a few percent of pixels will be displayed. ps uses opacity to indicate the selection range of a pixel. If the selection range of all pixels in the selection is less than or equal to 50%, the area will not be visible.