Photoshop selection Strategy

Introduction in the use of Adobe Photoshop design and processing of images, we will use a lot of adjustments to the specific areas, here we take Photoshop6.01 as an example, to carefully talk about the selection of a variety of selection methods.

To meet the needs of various applications, Photoshop offers three selection tools: Marquee tools, lasso tools, magic wand tools. These three common tools exist in the Toolbox (Figure 1), and if you don't see the toolbox on the screen, select Window-Display tools.

Figure 1


The Marquee tool contains four buttons, and the Lasso tool contains three buttons. Usually only selected one for the display state, the other is hidden, we can use the right mouse click to display all the buttons (such as Figure 2) (note: Hold down the SHIFT key while using the shortcut keys to choose the hidden button).

Figure 2

Each selection tool has its own options, and you usually make the necessary settings in the options panel before using the selection tool (Figure 3). The options for all of the selection tools have been lumped together in Figure 3, so that they can be used more intuitively by their comparison.

Figure 3

From Figure 3 We can see that all of the selection tools have one thing in common, that is, not only can you create a new selection, but you can also set up a new selection with an existing selection (add to a selection), the difference set (subtract from the selection), and the intersection (the selection crosses).

To handle the effects of the selection edges, we should understand two very important concepts: feather and anti-aliasing.

Feathering blurs the edges by creating a transition between the pixels around the selection and the selection. So the blur edge will lose some detail on the edge of the selection, and we can control the feathering of the selection by entering the feather value (Figure 4); antialiasing smooths the jagged edges of the selection by softening the color conversion between the edge pixels and the background pixels, No details are lost because only the edge pixels are changed.

Figure 4

Marquee Tool

We can specify the style for the Rectangle marquee tool and the elliptical marquee tool. When the style is normal, you can create selections at will; when the style is a constraint aspect ratio, the width and height input boxes are activated to control the aspect ratio of the selection by entering values; When the style is fixed, we can directly enter the length and width values to precisely control the size of the selection. (Note: If you hold down the ALT key, the selection you create is centered by the mouse, and if you hold down the SHIFT key, you create a square or a circle).

The Single-line Marquee tool and the Single Column marquee tool can select one row or a row of pixels, respectively (note: The selection of selections by the selection tool is the first and last, closed area, except that the Single box marquee tool and the Single column marquee tool select only one pixel width, so the selection looks like a dotted line, but zoom in, It is still a closed area.

Lasso Tool

The Lasso tool can draw a selection with the mouse at random; the Polygon lasso tool can draw a polygon selection through successive clicks of the mouse; The magnetic lasso tool is suitable for fast selection of objects with strong edges and edges, so there are several unique option settings, Width determines the size of the area around the magnetic lasso detection pointer, The edge contrast determines the sensitivity of the lasso to the edge of the image, and the higher values only detect edges that are in sharp contrast to their environment, while lower values detect low contrast edges. The final stylus pressure option is set for users who have a stylus drawing tablet.

Magic Wand Tool

The Magic Wand tool can select areas of consistent color without having to track their contours. A lower tolerance value allows the wand to select a color that is very similar to the pixel you click, and a higher tolerance value can choose a wider range of colors. If continuous is selected, all adjacent pixels within the tolerance range are selected. If "For all layers" is selected, the Magic Wand tool will select colors in all visible layers or only in the current layer.

Photoshop not only provides us with a powerful selection tool, but we can also modify, transform, store, and so on the selected selection menu (Figure 5).

Figure 5

If you want to select a selection that you just selected, you can choose Select to select Again (Note: "Re-select" is activated only if there are no selections).
The color Range command selects the specified color or color subset within an existing selection or a whole image. Choose select à color range to eject the Color Range dialog box (Figure 6). In the selection bar we can choose our own sample color, also can choose red, yellow, green, green, blue, magenta or high light, midtones, darkened and overflow (note: "Overflow" option only for RGB and lab images). The color tolerance option selects pixels by controlling the extent to which the related color is included in the selection (note: the "tolerance" option for the magic wand increases the range of colors that are fully selected). We can also adjust the selection, use the Color tool to click on the preview or image area to add colors, and use the Subtractive tool to click on the preview or image area to remove the color. (Note: If the "any pixel is not greater than 50% selection" information box, the selection border is not visible, you may have selected a color, but the image does not contain the full saturation of this color)

Figure 6

The feather command feathering the selection, the same as the feather effect in the tool options. The Modify command has four subcommand: You can create a ring selection with an extended edge command, and it is an anti-aliasing selection (Figure 7).

Figure 7

The smoothing tool clears the scattered pixels left and outside of the color-based selection, smoothing the selection (Figure 8).


Figure 8 The expand and shrink command expands or shrinks the selection by the input pixel value (Figure 9).

Figure 9

The expand Selection command adds all adjacent pixels in the tolerance range specified by the Magic wand option to an existing selection, and the Select similar command adds all the pixels in the entire image that are within the tolerance range to the existing selection.

The transform Selection command allows us to move, rotate, scale, and skew the selection. You can manipulate it either directly with the mouse or by entering a value in its options bar (Figure 10).

Figure 10

For a selection that needs to be preserved, it can be stored with the Save Selection command, which can be invoked by executing the load selection command.

Speaking here, we should have a comprehensive understanding of the powerful function of the constituency tool, and mastering the selection tools can not only improve the efficiency of image processing, but also lay a solid foundation for the future to become a master of processing.