You can move a selection border around an image, hide a selection border, and invert a selection so that the previously unselected part of the image is selected.
Note:
To move the selection itself, not the selection border, use the Move tool. See Move a selection.
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Drag the border to enclose a different area of the image. You can drag a selection border partly beyond the canvas boundaries. When you drag it back, the original border reappears intact. You can also drag the selection border to another image window.
Original selection border (left), and selection border moved (right)
Note:
You can apply geometric transformations to change the shape of a selection border. (See Apply transformations.)
from
the options bar, and position the pointer inside the selection border.
The pointer changes 
to indicate
that you can move the selection.- To constrain the direction to multiples of 45°, begin dragging, and then hold down Shift as you continue to drag.
- To move the selection in 1‑pixel increments, use an arrow key.
- To move the selection in 10‑pixel increments, hold down Shift, and use an arrow key.
- Choose View > Extras. This command shows or hides selection edges, grids, guides, target paths, slices, annotations, layer borders, count, and Smart Guides.
- Choose View > Show > Selection Edges. This toggles the view of the selection edges and affects the current selection only. The selection edges reappear when you make a different selection.
You can use the selection tools to add to or subtract from existing pixel selections.
Before manually adding to or subtracting from a selection, you may want to set the feather and anti-aliasing values in the options bar to the same settings used in the original selection.
in
the options bar, and drag to add to the selection.
in
the options bar, and drag to intersect with other selections.
in the options bar, and drag.
The Border command lets you select a width of pixels inside and outside an existing selection border. This can be useful when you need to select a border or band of pixels around an image area, rather than the area itself, for example to clean up a halo effect around a pasted object.
- Choose Select > Grow to include all adjacent pixels falling within the tolerance range specified in the Magic Wand options.
- Choose Select > Similar to include pixels throughout the image, not just adjacent ones, falling within the tolerance range.
To increase the selection in increments, choose either command more than once.
Note:
You cannot use the Grow and Similar commands on Bitmap mode images or 32‑bits-per-channel images.
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For each pixel in the selection, Photoshop examines the pixels around it, to the distance you specify in the radius setting. If more than half of these surrounding pixels are selected, the pixel remains in the selection, and the unselected pixels around it are added to the selection. If less than half the surrounding pixels are selected, the pixel is removed from the selection. The overall effect is to reduce patchiness and smooth sharp corners and jagged lines in the selection.
The Refine Edge option improves the quality of selection edges, letting you extract objects with ease. You can also use Refine Edge options to refine a layer mask. (See Adjust mask opacity or edges.)
- Click Refine Edge in the options bar, or choose Select > Refine Edge. Then set the following options:
View Mode
From the pop-up menu, choose a mode to change how the selection is displayed. For information about each mode, hover the pointer over it until a tool tip appears. Show Original displays the original selection for comparison. Show Radius displays the selection border where edge refinement occurs.
Note:
Brush over soft areas such as hair or fur to add fine details to the selection.
Note:
Because this option changes pixel color, it requires output to a new layer or document. Retain the original layer so you can revert back to it if needed. (To easily see changes in pixel color, choose Reveal Layer for the View Mode.)
Anti-aliasing
Smooths the jagged edges of a selection by softening the color transition between edge pixels and background pixels. Because only the edge pixels change, no detail is lost. Anti-aliasing is useful when cutting, copying, and pasting selections to create composite images.
Anti-aliasing is available for the Lasso tool, the Polygonal Lasso tool, the Magnetic Lasso tool, the Elliptical Marquee tool, and the Magic Wand tool. (Select a tool to display its options bar.)
Note:
You must specify this option before using these tools. After a selection is made, you cannot add anti-aliasing.
Feathering
Blurs edges by building a transition boundary between the selection and its surrounding pixels. This blurring can cause some loss of detail at the edge of the selection.
You can define feathering for the Marquee tools, the Lasso tool, the Polygonal Lasso tool, or the Magnetic Lasso tool as you use the tool, or you can add feathering to an existing selection.
Note:
Feathering effects become apparent only after you move, cut, copy, or fill the selection.
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Note:
A small selection made with a large feather radius may be so faint that its edges are invisible and thus not selectable. If you see the message “No pixels are more than 50% selected,” either decrease the feather radius or increase the size of the selection. Or click OK to accept the mask at its current setting and create a selection in which you cannot see the edges.
Selection without feathering and with feathering
A. Selection with no feather, same selection filled with pattern B. Selection with feather, same selection filled with pattern
When you move or paste an anti-aliased selection, some of the pixels surrounding the selection border are included with the selection. This can result in a fringe or halo around the edges of the pasted selection. These Layer > Matting commands let you edit unwanted edge pixels:
Color Decontaminate replaces background colors in fringe pixels with the color of fully selected pixels nearby.
Defringe replaces the color of fringe pixels with the color of pixels farther in from the edge of the selection that lack the background color.
Remove Black Matte and Remove White Matte are useful when a selection is anti‑aliased against a white or black background and you want to paste it onto a different background. For example, anti‑aliased black text on a white background has gray pixels at the edges, which are visible against a colored background.
Note:
You can also remove fringe areas by using the Advanced Blending sliders in the Layer Styles dialog box to remove, or make transparent, areas from the layer. In this case, you would make the black or white areas transparent. Alt-click (Windows) or Option-click (Mac OS) the sliders to separate them; separating the sliders allows you to remove fringe pixels and retain a smooth edge.
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