Tutorial: Selecting stuff

Level: Intermediate. Published on 31 October 2001 in Photoshop

This tutorial provides a thorough treatment of the various selection methods in Photoshop. Learn how to accurately select the parts of the image you want to use (and avoid the bits you don't!).

This tutorial will show you some ways to select areas of your images using the variety of selection tools available in Photoshop. First we'll talk about why selecting part of an image is so useful, and then we'll examine the various selection methods in Photoshop: the Marquee tools; the Lasso tools; the Magic Wand tool; the Color Range tool; and the Quick Mask mode. Finally, we'll look at ways to modify and fine-tune your selections. Enjoy!

Why use selections?

Selections are a great way to work on parts of your image independently, rather than manipulating the image as a whole.

Once you've selected a part of an image (e.g. a person's head or other object), you can then manipulate this object separately from the rest of the image. This means you can cut the object out; add drop shadows; adjust the brightness/contrast; warp it; apply effects and filters easily - in fact, anything you like!

Now let's look at the different selection tools in Photoshop, starting with the Marquee tools.

The Marquee tools

The simplest selection tools to use are the Marquee tools. These include the Rectangular, Elliptical, Single Row and Single Column tools. Activate the tools by clicking and holding the mouse button on the top-left tool in the Tools palette:

Click on the tool you would like to use. The Rectangular Marquee tool lets you select a square or rectangular area; the Elliptical Marquee tool selects a circular or elliptical area; and the Single Row and Single Column tools select a single line of pixels either horizontally or vertically.

To use one of the Marquee tools, click and drag out the selection with the mouse in your image:

By holding down the Shift key while dragging, you can constrain the selection to a square (for the Rectangular Marquee tool) or a circle (for the Elliptical Marquee tool):

Also, by holding down the Alt key while dragging, you can drag from the centre of the selection rather than from the edge - this is great for positioning circular selections precisely! Try it out to see what I mean.

The Lasso tools

The Lasso tools are great for seleting well-defined, irregularly-shaped areas. For example, they work well on strong foreground features of an image, such as a person's head.

To use the Lasso selection tools, click and hold the mouse on the Lasso tool icon in the Tools palette:

Click on the tool you'd like to use. The best way to learn about these tools is to try them out, but here are some pointers for you:

Lasso tool

The regular Lasso tool lets you select freehand areas by clicking and dragging with the mouse - when you release the mouse the "loop" is closed, completing the selection. This tool is great for quickly selecting a rough area.

Polygonal Lasso tool

The Polygonal Lasso tool lets you create selections based on straight lines (or segments). This allows you more precise control when selecting using the mouse. Click with the mouse in your image to add the first fastening point, then move the mouse and click again to create a new fastening point with a segment in between. Continue in this way until you're done, then close the selection border by moving the mouse over the first point and clicking (double-clicking with the mouse will also close the selection automatically). Try it!

Magnetic Lasso tool

The Magnetic Lasso tool is similar to the Polygonal tool, but it tries to add fastening points automatically based on the edge of the area you're selecting. For this reason, the magnetic lasso tool works best when selecting areas that contrast well with their surroundings. As with the Polygonal tool, you click to start it off. You can also add your own points by clicking. Finish the selection by moving the mouse over the first point and clicking, or just double-clicking.

The Magnetic Lasso tool's options let you control the tool's sensitivity:

"Width" controls the range of pixels around the mouse pointer within which the tool looks for the edge of the object you're tracing. If your object has well-defined edges you can set a high "Width" value and trace the object quickly and roughly. For more blurred edges, reduce the width and trace more precisely.

"Edge Contrast" specifies the tool's sensitivity to the edge of the object you're selecting. A high Edge Contrast value will only detect edges that contrast strongly with the rest of the image, whereas a lower value will detect softer edges.

The "Frequency" option controls how often the Magnetic Tasso tool will automatically place fastening points. A higher Frequency value will place more fastening points as you trace round the object.

Lasso tips

• If you place a fastening point incorrectly with the Polygonal or Magnetic Lasso tools, press the Delete key on the keyboard to "undo" the point. You can keep pressing Delete all the way back to the first fastening point if necessary.
• As well as the automatic points added by the Magnetic Lasso, you can add your own manual fastening points by clicking with the mouse.
• You can temporarily turn the regular Lasso tool into the Polygonal Lasso tool by holding down Alt (Windows) or Option (Mac), then releasing the mouse button, then clicking where you want the end of the straight line segment to be. To revert to the regular Lasso, release the Alt/Option key while the mouse button is held down.
• Likewise, you can turn the Polygonal and Magnetic lasso tools into the regular Lasso tool by holding down Alt/Option and dragging with the mouse.
• The Magnetic Lasso tool can be turned into the Polygonal Lasso tool by holding down Alt/Option and clicking with the mouse where you want the straight line segments to end.
• As well as double-clicking to close polygonal and magnetic selections, you can also hold down the Control key and click.

The Magic Wand tool

The Magic Wand tool is a great way to select irregular-shaped objects that are just one colour (for example, a red rose, or a person's hand). To activate the tool, click on the Magic Wand icon in the Tools palette:

To use the tool, click inside the object you would like to select. You'll see that the tool selects all the pixels that are similar in colour to the pixel you clicked on:

Often, your object will contain a couple of colours; in the above example, the flower has a green centre as well as the red petals. To select the centre as well, we simply hold down the Shift key and click in the centre to add to our selection (see "Adding and Subtracting" further down the page):

"Tolerance" setting

The "Tolerance" setting lets you to control the sensitivity of the Magic Wand tool:

If the Tolerance value is high, a wider range of colours will be selected. For example, if you click on a red pixel when the Tolerance is set very high, the Magic Wand tool might also select pixels that are pink and orange. If you set the Tolerance to a lower value, then only pixels that are very similar to the shade of red you clicked on will be selected. Experiment with different Tolerance values so that most or all of your object gets selected, without selecting the background as well.

"Contiguous" option

If you check the "Contiguous" box next to "Tolerance", then only adjacent areas of the same colour will be selected. If you deselect "Contiguous", all pixels of the same colour will be selected.

The Color Range tool

The Color Range tool is great for selecting particular colours in your image - for example, all the reds, or all the greens. You can then work on these specific colours - turning them from green to red, for example, or removing particular colours from the image.

This tool doesn't work well for selecting particular areas of your image (such as a foreground object), as it has a tendency to only partially select pixels, and often selects unwanted parts of your image that are a similar colour. But it's great for selecting colours to work on!

To use the tool, choose the Select > Color Range menu option. You'll see the "Color Range" dialog appear:

The most flexible way to use the tool is in the "Sampled Colors" mode (choose Sampled Colors from the Select: drop-down box). Click with the mouse in the document window on an area of your image that contains the colour you want to select. You'll then see this colour range turn white in the preview inside the "Color Range" dialog. This means that this range has been selected.

Changing the selection

To increase the degree to which colours in the colour range are selected, increase the "Fuzziness" slider. You'll see increasing areas of the preview image turning white as the degree to which each pixel is selected increases. Slide the slider to the left to decrease the intensity of the selection.

You can add to the range of selected colours by holding down the Shift key and clicking on new areas of colour in your image. Alternatively, you can click on the eyedropper icon with the little plus sign in the "Color Range" dialog.

Likewise, you can subtract colours by holding down the Alt/Option key and clicking in the image, or selecting the eyedropper icon with the minus sign then clicking in the image.

Preview options

You can click on the Image radio button to preview the entire image in the dialog (useful if you can't see all of the image in the main window). Click the Selection radio button to revert to the normal preview mode.

You can also preview the selected areas in the main document window using the Selection Preview drop-down box. You can choose from the following options:

• Grayscale shows how the selection will appear if converted to a channel.
• Black Matte will show the selected areas in colour over a black matte background.
• White Matte will show the selected areas in colour over a white matte background.
• Quick Mask shows how the selection would look in Quick Mask mode, using the current Quick Mask settings (see below for info on the Quick Mask mode).

Color Range presets

The Select: drop-down box allows you to choose various preset colour ranges, such as all Reds, Blues or Greens in the image. You can also select just the Highlights, Midtones or Shadows.

Out of Gamut will select all the colours in the image that are out-of-gamut (i.e. cannot be printed).

An example

In this example, we want to select all the green leaves in the image so that we can change their colour. To do this, we use the Color Range tool in "Sampled Colors" mode, then Shift+click on a couple of leaf areas to select a broad range of greens:

We then click OK to create the selection, and use Image > Adjust > Hue/Saturation to change the leaves from green to brown, without affecting the rest of the image:

And that's how to turn a summer scene into an autumn scene! :)

The Quick Mask mode

Photoshop's Quick Mask mode is a really versatile way of selecting stuff. Instead of creating marquees as you do with the other tools, you can actually "paint" the selection using any of Photoshop's painting tools. You can even use the other selection tools on the Quick Mask, as if it was a regular image! This makes the Quick Mask mode a very powerful feature of Photoshop.

To activate Quick Mask mode, click on the Edit in Quick Mask mode button in the Tools palette, or press the Q key:

You may like to select something with a regular selection tool (e.g. the Marquee tool) before entering Quick Mask mode, so that you can clearly see what's selected and what isn't:

You can see that the un-selected areas of the image are covered with the red mask when in Quick Mask mode.

You can now "paint" on the mask using any of the painting tools (Pencil, Paintbrush, Airbrush, etc), and use the Eraser tool to erase areas of the mask (in other words, to select more pixels). You can even use other tools such as the Fill and Smudge tools.

When you're ready, you can click the Edit in Standard Mode button to switch back to the regular marquee selection (or press the Q key again):

Modifying selections

Once you've made your basic selection using the above tools, there are a lot of things you can do to play around with it. In this section we'll look at feathering, anti-aliasing, adding and subtracting, bordering, smoothing, and expanding and contracting.

Feathering

Many of the selection tools include a "Feather" option:

Feathering blurs the edges of the selection so that the selection partially blends with the non-selected area. Note that feathering causes some loss of detail in your selection!

Feathering is useful for "softly" selecting an area of an image. Then, when you manipulate the selection, the boundary between the affected areas and the non-effected areas will not be a harsh line, but the effect will gradually fade towards the edge of the selection:

To feather the selection, enter a value greater than zero in the "Feather" option shown above 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.

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:

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:

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:

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:

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).

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.

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.

Conclusion

We hope this tutorial has given you a good insight into the wide range of selection methods available in Photoshop. As you can see, working with selections is a big topic. You will find that by playing around with the selection tools and learning how they work, you will open up new possibilities for image effects and manipulation. Good luck! :)

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