Photoshop C an Introduction mask by benbenzhou


More Info
									Selection Tools

There are several ways to select a portion of an image. The correct selection tool – will
largely depend on what you are selecting – and, what you want to do with it after you
select it. Learning the various methods – and, their results will help you best determine
the selection method to use. (And – Practice! Practice! Practice!)

Rectangular and Elliptical Marquee

You have already used the Rectangular Marquee tool in the previous exercise when you
were selecting a portion of John’s face. This tool draws a rectangular (or square) shape.

You already got some practice– but, let’s go ahead and practice a bit more to make sure
you understand how to use this tool.


1. Open the file named quiltsquares.jpg
2. Select the Rectangular Marquee tool
3. Move the tool onto the image until you
   see the crosshair
4. Click and drag over the 4 squares ( # 2
   and 3 in Row 3 and # 2 and 3 in Row 4)
5. You should see the “marching ants”
   around your selection

Now – what if you wanted to add 2 more
squares to this selection? And, they were
nowhere close to your current selection?

6. On the Selection Option bar – you will
    select the item “Add to Selection”
7. Now click over 2 additional squares and
    all items should now be selected!
8. You can now decide to eliminate a square (#3 in Row 3) by using Subtract from
9. On the Selection Option bar – click on Subtract from Selection and draw over Square
    #3 Row # 3 (which was already selected). (You may need to do this a few times to
    get it as neat as you like!)
10. Use your “layer via copy” options to see the various results from your selection

Intersect with selection – this option only will select those areas that “intersect” with your
new selection. Go ahead and try it – draw over unused / used selected areas and see
which area is ultimately selected!

These selection techniques can prove to be very handy when trying to manipulate

Note: Hold down the SHIFT key to have your Rectangular Marquee tool draw a perfect

July 2008                               Chapter Three                                 Page 28
Other things to know:

If you choose FEATHER from the select option – it will “soften” or feather your selected
area. The higher the number – the softer the edge. This can be good when you want to
copy something and diffuse the edges.

You can see in this example how the feathered edges of the selected quilt squares –
softened them:


                                      1.   Use the “feathered” option and Layer-Via-
                                           Copy to see the results.
                                      2.   You will have to do something to accurately
                                           see the results when you use layer via copy
                                           – what is it?

The Elliptical Tool works the same way (you hold down the SHIFT key to draw a perfect
circle!) – and, you may add / subtract and intersect in the same way.

Alias and Anti-Aliased

Images are made up of square pixels (remember?) – Your image may be an “aliased”
image – these square pixels are displayed across curved edges. Anti-alias allows the
curves to be smoother and not have the jagged edges you may sometimes see.

                       ALIAS                                    ANTI-ALIAS

July 2008                            Chapter Three                               Page 29
The Lasso Tools

The Lasso Tool includes the Lasso Tool, the Polygonal Lasso Tool and the Magnetic
Lasso Tool. All of these tools can be used to help you select odd shaped images using
free-form selection techniques. Each of these tools works a little differently – so
practicing with these tools will help you determine the right tool to use in different


1. Start by opening the image:
2. Select the Lasso Tool to begin
   your practice. This tool allows
   you to click and drag a freeform
   line around the image.
3. Holding the mouse button down
   move the mouse pointer around
   the image to draw your freeform
   selection area
4. When you get close to the end,
   simply release the mouse button
   and the lasso will automatically
   complete the selection.

This tool can make it difficult to create
an accurate selection and may
require quite a bit of editing to get a
final selected image.

Polygonal Lasso Tool

1. On the main menu – click on SELECT and then DESELECT – this will deselect the
   image so that you may begin the practice again. You will use this option a LOT!
2. Now – this time, select the Polygonal Lasso tool
3. This tool allows you to click each point you want to set around the image (think “dot
   to dot” books from when you were a kid!)
4. The more points you set – the better the final selection – don’t forget to zoom in
5. When you are done – either click the starting point, or double click to complete the

Hint: While selecting – you can press the DEL key to delete the last point set, or ESC to
deselect everything and start over (this will work with the Magnetic Lasso Tool as well!)

Magnetic Lasso Tool

Before you begin practicing this one – understanding how it works (and the options you
can use) may help you determine if this is a good selection tool for your application.
The Magnetic Lasso Tool works by determining the “contrast” within the image in the
area you are “dragging” the lasso over. The better the contrast – the better the final
selection area.

July 2008                               Chapter Three                             Page 30
1. Our cake has a clear “white”
   edge which should allow for
   us to create a good
   selection area with the
   Magnetic Lasso tool.
2. Before beginning; deselect
   the currently selected area –
   remember – Select /
   Deselect, and, then select
   the Magnetic Lasso tool.
3. You are going to “trace” the
   image by dragging along the
   edges of the image. As you
   do this you will see the tool
   automatically setting
   “points” (you can also force
   a point at anytime by
4. On the Option bar for the
   Magnetic Lasso Tool – you
   can use Feather (softens
   the edges), Anti-Alias (turn
   this on to get smoother
   curves) and Width (sets the detection width of the tool in pixels. The lower the
   number – the closer you will have to be to an edge for a selection, Edge Contrast
   (the higher the value the better the selection and Frequency (determines how many
   points are set during the selection process.

Hint! Turn on CAPS-LOCK to make the tool a “cross-hair” which will allow you to see
the selection area more clearly. By the way – this is a good one to remember – if you
accidentally press Caps-Lock – it will automatically turn your pointer into a cross-hair!

Magic Wand Tool

The Magic Wand allows you to click a spot in an image and a selection area will be
created based on the color of the spot you
clicked on. This tool can be very useful – but,
it is very tricky as well.


1. Close the slice of cake image (no need to
   save the image)
2. Open the image called apples.jpg and
   select the Magic Wand Tool
3. Click a spot on one of the apples and
   notice the area selected
4. Now adjust the Tolerance on the Option
   bar to a higher value and click again – as
   you increase the value – the tool will select
   a larger area with a wider area of color

July 2008                              Chapter Three                                Page 31
5. Experiment with the different Options to see how the Magic Wand selection areas
   vary with your choices.

Contiguous only allows selections in the adjacent areas – if not checked – colors that
match in all area of the image will be selected. Sample all layers will recognize colors
that match on all visible layers.

Saving and Loading Selection Areas

Once you have an area selected – it may be that you will need this selected area to be
available to you over and over. Rather than having to reselect it each time – it can be
much easier to “reload” the selection for use.

In order to do this – you must “save” the selection area.

1. Click on Select
2. Click on Save Selection
3. Name your selection (the selection is only available with this PSD file – so make sure
   you save a PSD file when working on your image to use this option!)

To reuse this selection at a later time:

1.   Click on Select
2.   Click on Load Selection
3.   Choose the name of the Selection and click on OK
4.   The area is now re-selected

Handy Options on the Select Menu

Select All:            Selects the entire image
Deselect:              Removes the selected area
Reselect:              Reselects an area that has been “deselected”
Inverse:               Inverts the selection so that everything *but* the original selected
                       area is selected
All Layers:            Selects all layers
Deselect Layers:       Deselects all layers
Similar Layers:        Selects similar layers (for instance: all TYPE layers)
Color Range:           Creates a selection based on a sampled color. You can control
                       the selection by using the “Fuzziness” setting. Increasing
                       fuzziness increases the area that is selected. (You can preview
                       this option).
Feather:               Feathers the selection of a set number of pixels (softens the
Modify:                Changes the currently selected area – by creating a border,
                       smoothing the selected area, expanding the selection or
                       contracting the selection.
Grow:                  Expands the selection to include adjacent pixels based on
Similar:               Expands the selection to include all pixels in the image that
                       are similar to the selected area.
Transform:             Allows to you perform a free transformation on the selected area.

July 2008                                  Chapter Three                            Page 32
Load Selection:       Allows you to load a previously saved selection.
Save Selection:       Allows you to save a selected area to use again later.

Quick Mask Mode

Quick Mask allows you to create a very detailed selection by using painting tools rather
than selection tools. In this mode you will typically mask off areas that you do not want
to have selected.

When you paint an area while in Quick Mask
mode – it will be highlighted in red and this
indicates it will be excluded from your
selection. When you are in Quick Mask
mode your foreground / background color
will be gray scale – and, Quick Mask will
appear in the title bar. These visuals will
keep you from getting confused when


1. Close the apple file
2. Open the image leaning.jpg
3. We are going to mask off the sky so that
   we can select just the tower
4. To help in this process – we will start by
   drawing an initial selection area with the
   Rectangular Marquee – and, then
   entering Quick Mask Mode – this will
   have much of the area already pre-
   selected for us
5. Notice in the next example how that
   area helps – and, how the colors
   have been changed to black / white
   and the words “Quick Mask” appear
   in the image title bar.

Remember that the Quick Mask mode
masks off areas in “red” so you can see
we just have a little clean up to do to
make this work!

6. Use the paintbrush and the eraser to
   “paint out” the blue sky – and, to
   ensure you have all of the building.
7. Don’t worry too much about making it
   perfect – we will see in later lessons
   how to adjust our brushes and sizes
   more easily.
8. When you think you are done – click
   on the STANDARD button to leave

July 2008                             Chapter Three                                Page 33
   Quick Mask and return to Standard mode of Photoshop.

9. Save the selection before going any further – Click on Select / Save Selection and
    give it a name and then click on OK
10. Now you can isolate the tower by using Select Invert – and, the pressing the Delete
11. Try it now!
12. Save this PSD file – we are going to
    use that isolated leaning tower later!
13. File / Save
14. Name the PSD file: leaningtower.psd
15. Will your selection from Step 9 be
16. If you had saved this as a flat image file
    – would your selection have been
    saved? Why or Why Not?

You will use Quick Mask mode more than
you might think you will. We will return to
this image again later to provide you more

July 2008                             Chapter Three                              Page 34
Cool Selection Techniques / Tips:

Combine Selections:

You can combine selections! First make a selection with any one of the tools – switch
tools and press the SHIFT key before you add to your selection. As long as you are
holding down the SHIFT key (you will see a small plus sign next to the tool) you can
continue to add to your selection as much as needed.

Deselecting Part of an Existing Selection

You can subtract selections by holding down the ALT (Windows) or OPTION (Mac)
button with the selection tool active. You will see a small minus symbol next to the
Selection tool. Select the portion of the selection you wish to deselect (remove) and it
will be removed from your selection and added back into the image.

Don’t Forget the Keyboard Shortcuts!

July 2008                              Chapter Three                               Page 35

To top