What are Selection Tools?



 

 

 

 

 

The selection tools allow you to select a portion or a subset of an image to work on. Most of Photoshop’s other tools and filters can then be applied to this selected area, altering its color, shape, texture, position and/or other attributes, while leaving the rest of the image untouched.

Photoshop contains three types of selection tools: the Marquee Tools, the Lasso Tools, and the Magic Wand.

The marquee tools are used to select a specific regularly shaped area. The marquee tools include the Rectangular, Elliptical, Single Row and Single Column Marquees:

The lasso tools are used to select an irregular area. These tools include the Lasso Tool, the Polygonal Lasso Tool and the Magnetic Lasso Tool.

The Magic Wand is used to select areas of an image based upon color; the Magic Wand does not have additional tools.

All of the selection tools may be used individually or in conjunction with each other to select exact areas of images. The Options Bar allows you to choose to add to or subtract from a previous selection:


    If you choose New Selection, any currently active selection will go away when you make your new selection. If instead you would like to add to the current selection, or subtract from it, make that choice in the Options Bar. You can even choose to select an area formed by the intersection of your selections.



How do I use
the Marquee Tools?
  The marquee tools let you select rectangles, ellipses, and 1-pixel-wide rows and columns.

To use the marquee tools:

1) Select a marquee tool: Rectangular (for a rectangular selection), Elliptical (for an elliptically shaped selection), Single Row (for a one-pixel wide row) or Single Column (for a one-pixel wide column).

2) Set the options you want in the Options Bar.

3) Drag over the area you want to select. Hold down the Shift key if you want to constrain the selection to a square or a circle.

 


How do I use
the Lasso Tools?
 

The Lasso Tool and Polygonal Lasso Tool let you draw irregular selection borders (both straight-edged and freehand):

  • If you want the selection to be completely or primarily freehand (with a minimum of straight edges) then use the Lasso Tool.

  • If you want the selection to be completely or primarily straight edges (with a miminum of freehand edges) then use the Polygonal Lasso Tool.

With the Magnetic Lasso Tool, you can draw the selection border, and it will automatically snap to a high-contrast edge in the graphic.

To use the Lasso Tool:

1) Select the Lasso Tool from the Toolbox.

2) Set any desired options in the Options Bar.

3) To draw a freehand segment of the selection, simply drag the mouse.

4) To draw a straight-edged segment of the selection, hold down the Alt key and click at the desired beginning and end points of the segment.

5) To close the selection border, let go of the mouse button (without holding down the Alt key).

To use the Polygonal Lasso Tool:

1) Select the Polygonal Lasso Tool from the Toolbox.

2) Set any desired options in the Options Bar.

3) To draw a straight-edged segment of the selection, click at the desired beginning and end points of the segment.

4) To draw a freehand segment of the selection, hold down the Alt key and drag the mouse.

5) To close the selection border, double-click the mouse button.

 
Tip: Think of the Lasso Tool and the Polygonal Lasso Tool as opposites of each other. One (the Lasso Tool) usually does freehand selections, but can be forced to make straight lines by holding down the Alt key, while the other (the Polygonal Lasso Tool) does straight line selections, but can be forced to do freehand by holding down the Alt key.

   

To use the Magnetic Lasso Tool:

1) Select the Magnetic Lasso Tool from the Toolbox.

2) Set any desired options in the Options Bar.

3) Click to set the first endpoint of the selection.

4) To draw a freehand segment, move the mouse pointer along the edge you want to trace. (You don’t have to hold down the mouse button, although you can if you like.)

5) As you move the pointer, the selection will automatically snap to the strongest edge in the area around the pointer, based on the Width set in the Options Bar. Periodically, intermediate points are added to the selection border. While tracing the edge, click to add a point if needed.

6) If you want to switch to either the regular Lasso Tool or the Polygonal Lasso Tool, hold down the Alt key. At that point, dragging the mouse will let you draw freehand borders; clicking will let you draw straight line segments.

7) Close the selection border by double-clicking the mouse.


How do I use
the Magic Wand?

The Magic Wand Tool lets you select areas of an image based on similar shades of color simply by clicking on the desired color.

To use the Magic Wand Tool:

1) Select the Magic Wand Tool from the Toolbox.

2) Set the desired options in the Options Bar:





   
  • Choose whether to
    - create a new selection,
    - add to an existing selection,
    - subtract from an existing selection, or
    - intersect with the existing selection.

  • Enter a value from 0 to 255 in the Tolerance box. A low number will let you select colors very similar to the pixel you click; a high number will let you select a broader range of colors.

  • To select only adjacent areas using the same colors, select Contiguous. Otherwise, all pixels using the same colors will be selected.

  • Check or un-check the Contiguous option. If Contiguous is not selected, all pixels that are the same color as the selected pixel will be selected, wherever they occur in the image. Otherwise, only adjacent pixels of the same color will be selected.

3) Click the color you want to select.

 





An example

 

 

 

 

To create the image at the bottom, we started with a photograph of a bouquet of daffodils:


Original Image


First we selected the yellow color ranges in the image, using the Magic Wand:


Magic Wand Selection


Next, we adjusted the selection to include just a single flower, using the Lasso Tool and the “add to” and “subtract from” selection options:


Adjusted Selection


Once only the single daffodil remained selected, we copied that selection and pasted it into a new file. We also created a green background layer. The result:


Final Image

 

 

 

 

 

 

 

 

End of Lesson

Copyright © 2001, Bloomsburg University Virtual Training Help Center.
All rights reserved. This material may not be used without written permission.
Contact Dr. Mary Nicholson at mjnich@bloomu.edu
The screenshots contained in this tutorial were created in Adobe Photoshop 6.0.