Modifying Selections in Photoshop

Learn how to alter existing selections in Photoshop. You explore feathering, anti-aliasing, adding/subtracting, bordering, smoothing, and expanding/contracting.

Once you've made your basic selection using one of Photoshop's numerous selection tools, there are a lot of things you can do to play around with it. In this tutorial we'll look at:

  • feathering
  • anti-aliasing
  • adding and subtracting
  • bordering
  • smoothing
  • expanding and contracting

Feathering

Many of the selection tools include a Feather option in the options bar:

Feather option

Feathering blurs the edges of the selection so that the selected area partially blends with the non-selected area:

Original selection
Original selection
Selection copied and pasted with 0% feathering
Selection copied and pasted with 0% feathering
Selection copied and pasted with 10% feathering
Selection copied and pasted with 10% feathering

To feather the selection, enter a value greater than zero in the Feather option before you create your selection. Alternatively, to feather a selection after it's been created, use the Select > Feather... menu option.

Anti-aliasing

Anti-aliasing is the process of reducing the jagged "staircase effect" caused when a line or curve of pixels of one colour meets a line of pixels of another, contrasting colour. Anti-aliasing is achieved by averaging the colours of the edge pixels of a selection between the selected area's colour and the background's colour.

Circular selection with no anti-aliasing
Circular selection with no anti-aliasing
Circular selection with anti-aliasing
Circular selection with anti-aliasing

Note that, unlike feathering, only the edge pixels are changed. Anti-aliasing does not blur outwards from the edge like feathering does.

To use anti-aliasing when making a selection, check the Anti-aliased option before creating your selection:

Anti-aliased option

Note that you must enable anti-aliasing before you draw your selection, as there is no way to add anti-aliasing afterwards!

Adding and subtracting

You can modify the shape of your selection by:

  • Adding new areas to the selection
  • Removing (subtracting) areas from the selection
  • Creating intersections with the selection and a new area

Adding

To add to an existing selection, hold down the Shift key while creating your new selection, or click on the Add to selection button:

'Add to selection' button

Subtracting

To subtract from an existing selection, hold down the Alt/Option key while creating your new selection, or click on the Subtract from selection button:

'Subtract from selection' button

Intersecting

To intersect with an existing selection, hold down the Shift and Alt/Option keys while creating your new selection, or click on the Intersect with selection button:

'Intersect with selection' button

Border

You can turn an existing selection into a border selection. A border selection selects just the edge of the original selection. To turn a selection into a border, pick the menu option Select > Modify > Border. In the "Width" box, enter how wide you would like the border to be (in pixels).

Original selection
Original selection
Bordered selection
Bordered selection

Smoothing

Smoothing rounds off the sharp edges of a selection by averaging the selected and non-selected pixels over a specified sample radius. This is great for creating smooth curvy selections, or for filling in bits that were missed out when using the Color Range tool.

To use smoothing, choose Select > Modify > Smooth. Enter a value for "Sample Radius" — the higher the value, the more pronounced will be the smoothing effect.

Original selection
Original selection
Smoothed selection
Smoothed selection

Expanding and contracting

You can change the size of your selection after you've created it. To make the selection bigger, choose Select > Modify > Expand and enter the number of pixels you'd like to expand the selection by.

Similarly, to make the selection smaller, choose Select > Modify > Contract and enter the number of pixels to contract the selection by.

Further reading

Of course, to be able to modify a selection, you first need to make a selection. The following tutorials take you through each of the main selection techniques in Photoshop:

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Responses to this article

1 response:

11-Jun-17 22:26
Very knowledgeable, thanks

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