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Photoshop

Selections

Manipulating Selections

Selections can be manipulated in a number of ways. After making an initial selection you can make an additional selection that can be added to, subtracted from, or intersected with the original. A selection marquee can be transformed in terms of its size, position, rotation, skew, and perspective.

You'll recall these Selection Option buttons from previous lectures. You can use these options on selections made with any type of selection tool.

New Selection

Unless you specify otherwise, every new selection will replace a previous selection. Let's say you create a selection with the Marquee tool and release the mouse button. If you so much as click again on the image with a selection tool, Photoshop assumes you want to draw a new selection and the old one will be removed. This is because the Selection Options are set to New Selection as the default behaviour.

Add to Selection

You may want to isolate more than one area of the image for modifications or select multiple areas with different colours. In the example at right, the Magic Wand tool was used to make the selections.

1. Make the first selection.
2. Click on the Add to Selection button in the Selection Options. The selection cursor will now display a small plus sign.
3. Make the second selection.

Photoshop will merge these into a single selection as shown here. The two selections don't need to be overlapping, though; they can be completely separated when you use this option. You aren't restricted to two selections either. You can add as many as you need.

Shortcut method. Create the initial selection and hold the Shift key down as you create the second selection. You will find this extremely useful.

Subtract from Selection

As you're fine-tuning a selection, you may want to remove areas from the selection. The process is exactly the same as before but you click the Subtract from Selection button before starting your next selection. The selection cursor will display a small minus sign.

In this first example, the objective was to select the button element (magnified here by 200%) using the Rectangular Marquee tool but extra space was inadvertently included at the bottom of the button. You can start over or you can subtract that extra unwanted portion of the selection. In the second image, after the Subtract from Selection button was enabled, another marquee was drawn to include the unwanted white pixels. The final image shows the result.

Shortcut method. Create the initial selection and hold the Alt (Option) key down as you create the second selection.

You can also use the Subtract from Selection option to "take a bite" out of another selection. In this example we wanted to create a selection in a crescent moon shape. The Oval Marquee tool was used with the Shift key held down to draw perfect circles. The first selection created the circle. The second selection subtracted a portion of the of the first selection, leaving the crescent-shaped selection as the final result.

Intersect With Selection

The last button in the Selection Options is called Intersect with Selection. This option compares the two selections and the resulting selection will contain only those areas that were common to both selections. After you draw your first selection, press the Intersect with Selection button and the selection cursor will display a small X sign. Then draw the second selection.

Let's say you want to create a wedge shape. You'd use the Oval Marquee tool and draw a circle. You would enable Intersect with Selection and switch to the Rectangular Marquee tool and draw a square that includes one-quarter of the circle. Once you release the mouse button, the area of the two selections that intersected (the wedge) remain.

Shortcut method. Create the initial selection and hold the Shift-Alt (Shift-Option) keys down as you create the second selection.

Remember that these add, subtract, and intersect options work for all the selection tools: Marquee, Quick Selection, Magic Wand and the Lasso tool variations. You can switch tools between one operation and another.

Transforming Selections

Once a selection has been made you can scale it, rotate it, skew it or apply perspective to its shape. Transforming a selection does not affect the underlying pixels. This just helps you to modify or reshape your selections.

To begin the process, go to Select > Transform Selection. Your selection will be enclosed in a Transform bounding box that is pictured in the table below. The table below is a key to various pointer icons. (Note: the grey selection in the three scale illustrations represents the original selection for demonstration purposes.)

Transforming Selections
		Bounding Box: This is a rectangle with eight handles on its corners and sides. As you move your cursor along the borders of the bounding box and outside of it, you'll see the pointer icon change depending on the cursor location. At the centre is the reference point.
		Horizontal Scale: This icon is displayed when the pointer is over a side handle. Dragging left or right will alter the width of the bounding box and selection.
		Vertical Scale: This icon is displayed when the pointer is over a top or bottom (middle) handle. Dragging up or down will modify the height of the bounding box and selection.
		Scale: This icon is displayed when the pointer is over a corner handle. Scaling will modify the width and height at the same time as you drag the handle. If you want to retain the width-to-height ratio of the bounding box as you scale, hold down the Shift key while dragging.
		Rotate: The bounding box and selection can be rotated freehand by dragging when this icon is displayed. It will appear when the cursor is outside the bounding box. To constrain the rotation to increments of 15o, hold down the Shift key while dragging.
		Move Reference Point: When rotating, the bounding box will rotate around its centre point, called the reference point. You can drag the reference point to another location if you want to rotate around a different point in the image. You can even drag it outside of the bounding box. While dragging the reference point, you can constrain its movement to 45o angles by holding down the Shift key.
		Skew: The Skew icon will only appear if you press Ctrl-Shift (Cmd-Shift) while you're holding the pointer over one of the four sides of the bounding box. This will apply a horizontal or vertical skew depending on which direction the arrow icon is pointing. Skewing will move one side of the bounding box in the direction you drag while the opposite side of the bounding box will remain in place.
		Perspective: The Perspective icon will only appear if you press Ctrl-Alt-Shift (Cmd-Opt-Shift) while you're holding the pointer over one of the four sides of the bounding box. Perspective will expand or contract two adjacent corners of the bounding box.

Other things to know about transforming selections:

• The Undo command can be used to undo the most recent in a series of transformations. For example, if you changed the width of the bounding box, then the height, and then rotated it, using Undo will reverse the rotation.
• To apply a transformation press Enter (Return) or click on the Commit Transform button in the Tool Options bar.
• To cancel the transformation or dismiss the bounding box before transforming, press the Esc key or the Cancel Transform button in the Tool Options bar.

Practice Exercise: Manipulating Selection Transformations

Try transforming a selection using the shapes.psd image found in your NewImages folder.

1. Select the lightning bolt using any of the methods you've learned.
2. Go to Select > Transform Selection.
3. Try scaling the selection horizontally.
4. Use the Undo command to undo the horizontal scaling.
5. Click and drag one of the corner handles while holding down the Shift key to scale the selection proportionately and release the mouse button when you're done.
6. Click on the Cancel Transform button in the Tool Options bar. This will dismiss the bounding box and return the selection to its original state.
7. Transform the selection again. This time, drag the reference point to another spot and then rotate the bounding box and selection.
8. After you've released the mouse button, undo the transformation.
9. Hold your cursor over the bottom border of the bounding box and press Ctrl-Shift (Cmd-Shift) to activate the Skew icon:
10. Once the icon appears, drag to the left or right to skew the selection.
11. Cancel the tranformation again, this time by pressing the Esc key.

Moving Selections

Selections created with the Rectangular and Elliptical Marquee tools can be repositioned while you are creating them by holding down the space bar.

To move a completed selection around the image by dragging, you must have a selection tool active. Click within the selection with either the Marquee, Lasso, Quick Selection or Magic Wand tool and drag. The tool's Selection Options must have New Selection enabled for this to work.

12. Try moving the lightning bolt selection down to the bottom of the window and back again. It's not necessary to move it back to exactly the same place.

You can use the Shift key to constrain the direction of movement to 45^o angles. Just make sure that you press the Shift key after you have clicked in the selection. If you click before that, you'll switch to Add to Selection mode.

Selections can also be moved by using the keyboard's directional arrow keys. One of the selection tools must be active for this to work. Clicking once on a directional arrow key will move the selection marquee one pixel. If you hold the Shift key down while pressing a directional arrow key, the marquee will move 10 pixels at a time. This speeds things up when you need to move the marquee a considerable distance.

13. Try moving the selection by three pixels using a directional arrow key.
14. Move the selection 10 pixels by holding down the Shift key while pressing a directional arrow key.

Select Menu Options

The following options modifying selections that are found in the Select menu.

Feather

When we looked at Feather previously, it was a tool option that had to be set before drawing a selection. The Feather command in the Select menu is used to apply feathering after a selection has been made. To access the command, go to Select > Feather... which will display the Feather Selection dialog. Here you set the radius of the feathered area.

In this example, a precise selection of the star had a Feather radius of 5 pixels applied (left). The selected area was copied and pasted onto a white background on the right to illustrate the soft effect.

Border

When Border is used, the edge of the selection area is converted to an anti-aliased outline or border. To use this option go to Select > Modify > Border... which will display the Border Selection dialog. The width of the border is determined by the value you set here.

The border selection shown on the left in this example is 5 pixels wide. This was copied and pasted onto a white background on the right to illustrate the effect.

Smooth

Smooth is used to clean up stray, unselected pixels within a selection area. The Select > Modify > Smooth... command will open the Smooth Selection dialog. Here, you set a radius value that will tell Photoshop how large of an area to consider when deciding whether to add or subtract unselected pixels to a selection.

In this example, a precise selection of the star was made and then a Smooth value of 5 pixels was used (left). The selection was copied and pasted onto a white background on the right to illustrate the effect. Notice how both the inner and outer the corners of the selection have been smoothed out.

Expand

Select > Modify > Expand Selection... will display the Expand Selection dialog. You set the distance you want to expand the selection by in the Expand By field.

In this example, a value of 5 was used. The result was copied and pasted onto a white background on the right to illustrate the effect.

Contract

Select > Modify > Contract Selection... will display the Contract Selection dialog. You set the distance you want to contract the selection by in the Contract By field.

In this example, a value of 5 was used. The result was copied and pasted onto a white background on the right to illustrate the effect.

Grow

Grow has a similar effect to adding to a selection using the Magic Wand tool. In fact, it uses the current Tolerance setting for the Magic Wand when it is applied. The command is accessed by going to Select > Grow. There are no options for Grow. It will increase the selection to include adjacent pixels that fall within the tolerance range set for the Magic Wand tool. Using the command repeatedly will add more pixels to the selection each time.

In this example, the centre of the star was clicked on with the Magic Wand set to a Tolerance of 32 (left) and Contiguous was enabled. The right image shows how the selection changed after the Grow command was used.

Similar

Select > Similar will execute the Similar command which has no options. It works nearly the same as Grow except that both adjacent and non-adjacent pixels will be considered and added to the selection if they are within the Magic Wand tolerance range.

In this example, the centre of the large star was clicked on with the Magic Wand set to a Tolerance of 32 and Contiguous was enabled (left). The right image shows how the selection changed after the Similar command was used. This expanded the selection to include all the pixels in the large star as well as those in the small star.

Inverting Selections

When you invert a selection, the selected areas become deselected and vice versa. To invert a selection, go to Select > Inverse or use the keyboard shortcut Shift-Ctrl-I (Shift-Cmd-I). This is something you'll be doing a lot so you'll save a lot of time if you commit the shortcut to memory.

It is especially useful in the situation we'll look at here. We want to select the balloon without including the background. To select the various colours of the balloon as well as the small details in the string and ribbon could be time-consuming.

Instead, we're going to select the background and then invert the selection so the balloon itself is selected. The Magic Wand tool was used to select only the background. Diagonal lines were added to illustrate the selected pixels.

Then the Inverse command was applied. After the selection was inverted, the selection enclosed all the pixels except for the background. This gave us the selection we wanted in two quick steps.

15. Open the History panel and click on the state where you made your initial selection around the lightning bolt.
16. Use the Select > Modify > Expand Selection... command to display the Expand Selection dialog. Type a value of 5 in the Expand By field and click OK. Your image should look similar to the one shown here.
17. Invert the selection using the Select > Inverse command or its keyboard shortcut Shift-Ctrl-I (Shift-Cmd-I). Now everything but the lightning bolt and the 5-pixel white margin around it will be selected.
18. You can close the file without saving.
    

Manipulating Selections Summary

• New Selection is the default selection mode.
• You can add to an existing selection by enabling the Add to Selection option.
• You can subtract from an existing selection by enabling the Subtract from Selection option.
• When the Intersect with Selection option is enabled, only the pixels common to the initial and subsequent selection will be retained.
• The Transform Selection command creates a bounding box around a selection that you can manipulate to scale, rotate, skew and add perspective to a selection.
• The bounding box's reference point can be moved, allowing the selection to be rotated around a non-centered point.
• Selections created with the Rectangular and Elliptical Marquee tools can be repositioned while you are creating them by holding down the space bar while dragging.
• Completed selections made with any selection tool can be moved if one of the selections tools is active. You can click within the selected area and drag the marquee to another location. Alternately, you can use the keyboard's directional arrow keys with or without the Shift key to nudge the marquee.
• Feathering creates a soft, semi-transparent edge to an existing selection.
• The Border command converts the edge of a selection to an outline.
• The Smooth command is used to add or subtract pixels to/from an existing selection.
• Expand will extend the boundary of a selection by the designated amount.
• Contract will shrink a selection by the designated amount.
• Grow adds adjacent pixels to a selection when they fall within the Magic Wand's current Tolerance range.
• Similar adds adjacent and non-adjacent pixels to a selection when they fall within the Magic Wand's current Tolerance range.

Manipulating Selections Keyboard Shortcuts:

• Add to Selection: Shift while making a subsequent selection
• Subtract from Selection: Alt (Option) while making a subsequent selection
• Intersect with Selection: Shift-Alt (Shift-Option) while making a subsequent selection
• Transform Skew: Ctrl-Shift (Cmd-Shift) while in Transform Selection mode
• Transform Perspective: Ctrl-Alt-Shift (Cmd-Opt-Shift) while in Transform Selection mode
• Commit Transform: Enter (Return)
• Cancel Transform: Esc
• Invert selection: Shift-Ctrl-I (Shift-Cmd-I)
• Nudge a selection one pixel: Press a directional arrow key
• Nudge a selection 10 pixels: Press Shift plus a directional arrow key

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Photoshop - TOC - Introduction - Books -
Selections - Links - Questions -
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Photoshop - TOC - Introduction - Books -
Selections - Links - Questions -
1 - 2 - 3 - 4 - 5 - 6 - [ 7 ] -