Adjusting selections numerically
You can use commands in the Select menu to increase or decrease the pixels in an existing selection and to clean up stray pixels left inside or outside a color-based selection.
To expand or contract a selection by a specific number of pixels:
- Choose Select > Modify > Expand or Contract.
- For Expand By or Contract By, enter a pixel value between 1 and 100, and click OK.
The border is increased or decreased by the specified number of pixels. Any portion of the selection border running along the canvas's edge is unaffected.
To frame an existing selection with a new selection:
- Use a selection tool to make a selection.
- Choose Select > Modify > Border.
- Enter a value between 1 and 200 pixels for the border width of the new selection, and click OK.
The new selection frames the original selected area.
The Border command creates an anti-aliased selection. (See Softening the edges of a selection.) To paint a hard-edged border around a selection, use the Stroke command. (See Filling and stroking selections and layers.)
To expand a selection to include areas with similar color:
- (Photoshop) 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.
Do one of the following:
To increase the selection in increments, choose either command more than once.
Note: You cannot use the Grow and Similar commands on images in Bitmap mode.
To clean up stray pixels left inside or outside a color-based selection:
- Choose Select > Modify > Smooth.
- For Sample Radius, enter a pixel value between 1 and 100, and click OK.
Photoshop or ImageReady checks around each selected pixel to find any unselected pixels falling within the specified range. For example, if you enter 16 for the sample radius, the program uses each pixel as the center of a 33-by-33-pixel area (16 pixels in the horizontal and vertical directions). If most pixels in the range are selected, any unselected pixels are added to the selection. If most pixels are unselected, any selected pixels are removed from the selection.
Note: The relationship between physical distance and pixel distance depends on the resolution of the image. For example, 5 pixels is a longer distance in a 72-ppi image than in a 300-ppi image. (See Understanding image size and resolution.)