Photoshop Lasso Tool: Selection Tools for Retouching

Photoshop’s lasso tool comes in handy if you’re looking to make a freehand selection, but that’s not all this tool can do. In fact, there are three kinds of lasso tools: the standard tool, the polygonal tool, and the magnetic lasso tool. Here’s how to use each one, along with a few designer shortcuts and tips to help you along the way. 

Quick Tip #1: The keyboard shortcut for the lasso tool is the letter L. To alternate between the three lasso tools, press Shift-L repeatedly.

The standard lasso tool 

In the physical world, you would use a pencil to trace a border or draw the outline of an object onto a piece of blank paper. In Photoshop, you perform this function digitally with the lasso tool. Simply click your mouse or stylus where you want the selection to begin, hold the selection down, and drag your lasso tool where you want it to go. To complete the selection, return to the spot you began, and the selection will automatically close its loop. Careful though, if you don’t end near the area you began, Photoshop will close the loop with a straight line.

While this process seems easy enough, it can be hard to draw a selection perfectly using a mouse or stylus. Keep the following ideas in mind when designing with the lasso tool: 

1. The standard lasso tool is great for chaotic, unpredictable, or random selections of objects. If you want to add a stain to a carpet, add clouds to a sunset, or change the hue of the inside of a seashell or flower or the lens of an eye, this is the perfect tool to use. 

2. Once you make a selection using the lasso tool, you limit the area you affect in your design to what’s within the crawling-ant-line. Go ahead and use your filters to blur, shade, or otherwise add to your selection, and the rest of your work will stay unchanged. Once you modify your selection, use the CTRL key to move it around wherever you please. 

3. With your lasso tool selected, press the Shift key to create a small (+) sign next to the lasso. This allows you to add to your already existing selection. Press the Option key for a (-) sign and subtract from your selection. By zooming in on your object, you can check on the accuracy of your lasso tool and add and subtract from your selection as needed. 

4. Press both the ALT + SHIFT key at the same time, then drag your lasso tool over a selection to turn on the “Intersect Selection” option. You can use this to join two objects and create a third selection where the previous two selections intersected. 

Quick Tip #2: If you need to make a selection around a large object that doesn’t fit within your document window, temporarily switch to a hand tool by pressing down the spacebar. 

The polygonal lasso tool

The polygonal lasso tool is great for creating straight lines and corners on well-defined shapes like city skylines, billboards, or laptop computers. These are shapes you may want to superimpose new images onto in a layout, just like we did in the tablet and iPhone pictures below: 

To superimpose an image within a mask, start by clicking the edge of the shape you want to outline. Follow lines of the shape, clicking at each corner to anchor a point, and then look for the small (°) circle at the end that tells you where to join the shape together so there are no holes in your mask.

Quick Tip #3: If you’re well into creating your shape and make a mistake, you don’t need to start over. Simply press the backspace key on your keyboard, and Photoshop will move you back a click.

Once you have a shape created, use it to make a mask in your layers window so you can superimpose a new image onto the image currently in your document. Here’s how:

1. Create a new layer with the image you want to superimpose (the Devil’s Sister whiskey image above) onto the shape you want it to appear on (the iPhone screen). 
2. Click on the square image on the bottom of your layers window to create a mask for that layer. 

3. Now you can transform your superimposed image to fit with the perspective, shape, and size of the picture it’s housed within. 

In the image above, the iPhone screen has been superimposed with the Devil’s Sister whiskey image simply by resizing the whiskey image. However, in the tablet view, the image needs to be skewed into the correct perspective to make sense with the rest of the image. Click on the Edit dropdown menu and choose Transform, or type Command-T to accomplish this. 

Quick Tip #4: There may be times when you need a not-quite-straight line within your polygonal mask. To move your cursor in more random directions, hold down your Alt or Option key and flip back to the standard lasso tool. Release the key to flip back to the polygonal lasso tool. 

Finally, if you are looking to select everything in an image but the mask you created, you can Inverse your selection using Control + Shift + I or Command + Shift + U. 

You can use this command to outline a person and change their background, put an object into a different room, or simply blur the background, make it black and white, or otherwise enhance it. You’ll often see this done in family portraits when the photographer wants to emphasize the people within the photograph by blurring the background, saturating it with sepia tones, or changing it to grayscale. Below is an example. Can you tell the background has been blurred? 

Magnetic lasso tool

The magnetic lasso tool is great for tracing around irregular objects, or for selecting clearly defined objects or parts of objects. Plus, Photoshop Creative Cloud includes enhanced magnetic lasso capabilities to help you create selections based on visual information available in the image.

To begin, click on any clear edge and start pulling slowly along the object. The magnetic lasso tool will automatically find the edge as you draw your cursor along the object. To stop tracing, simply click your mouse button or pen. 

The magnetic lasso tool creates points along the path as you draw. To determine how many points, you need to look at the frequency (located at the top toolbar on your screen). The larger the frequency number, the more points your lasso tool will make. 

Quick Tip #5: More points in your magnetic lasso tool selection mean more detail, but if you use too many points, a straight line can become jagged. A frequency of 50-60 is a pretty good setting to use for tracing most objects. 

Depending on the background of your image, you may also need to adjust your Contrast and Width settings on the magnetic lasso tool: 

• Contrast, as the name suggests, looks for how much contrast there is in your image. If your object fades into a background, you may need low contrast, meaning your tool is looking for exactly where you want the line to go. Higher contrast means the lasso tool can be more lenient when placing its line. 

• Width applies to how far your cursor can stray from the object’s outline while you are tracing the object. Again, if the background and object are hard to tell apart, you won’t want to stray too far. However, if you are tracing an object on a solid-colored background, you could easily and quickly outline the object by making a circle around it using a large width setting. 

The magnetic lasso tool is great for selecting clearly defined objects or parts of objects, but when it comes to tracing around something like hair, where the outline is not clear-cut, the tool starts to fail. Try using the Feather and Anti-Aliasing tools to get around this. 

• Feathering creates an effect around an imperfect selection, “feathering” your border a certain distance of your choosing. 

• Anti-Aliasing does the opposite, smoothing out jagged edges and making objects look more like they should. This often happens when working with low-resolution images that need retouching. 

Use lasso tools to create selections and make your work appear more accurate. If you’re hoping to retouch images, this is a skill you need in your Photoshop Toolbox. However, your work shouldn’t stop there. 

More selection tools and uses

Every Photoshop project is different, which means selection tools like those we’ve discussed thus far are important to master. However, you may also want to check out tutorials on the following Photoshop selection tools: 

• Photoshop pen tool: the most accurate tool for creating outlines 
• Marquee tool: for selecting shapes in your Photoshop document without having to outline them
• Magic wand tool: for selecting shapes based on color and tone

Each one of these tools has its own best practices, and it’s only by mastering them that you’ll know how to use Photoshop.

Have an image you need to select, but it’s too close in color to the background for the magnetic lasso tool? The Quick Selection Tool can detect incredibly specific color profiles and find the edge for you. It’s used best when selecting large objects and backgrounds and allows you to select more than one area at a time. However, if you want to select that tiny triangle of air inside the nook of a bent elbow, that blue that matches the blue air of the larger background, the quick selection tool might be difficult to use.

Need to outline text in Photoshop quickly? Select the Layer dropdown menu and choose Type. Creating a Work Path will allow you to mask text in the same way you masked an object with the lasso tool. 

Quick Tip #6: You can switch between your document’s layers while still maintaining your selection. Go ahead, toggle away.

The Content Aware function — found in the Edit dropdown menu under Fill — is one of Photoshop’s newest, smartest functions. You can use it to replace selections within an image with new information gathered from the rest of the photograph. The example below illustrates this:

Say you have this beautiful image of a lighthouse, only you need to remove the lighthouse. Using the content aware tool, we can easily replace the selected lighthouse with information from the rest of the image so you’d never know it was there in the first place. 

1. First, make a duplicate of the background image. This way, if you ever need to go back to the original image, you have it in easy reach. 

2. Using the standard lasso tool, make a selection of the image you wish to replace, in this case, the lighthouse. 

3. Go to the Edit dropdown menu and select Fill (or use the shortcut Shift + Delete). Then, choose the Fill option Content Aware. 

4. Now, the water tank has been completely removed, replaced by the beautiful clouds found in the rest of the image. 

You might have to zoom in on the image to see if any areas need to be cleaned up. If not—you’re good to go!

5. If there are areas that need to be cleaned up (see the two cloudy edges near the rocks above), use the clone stamp tool to make the transition more natural. 

The content aware tool in Photoshop’s Creative Cloud has made selecting and manipulating images so much easier than it ever was before. 

Applying filters to lasso tool selections

Finally, using filters to manipulate selections within a Photoshop document takes practice. Check out our tutorials on how to replace a color in Photoshop, how to erase the background, or how to blur, distort, or stylize your work with filters. 

Once you make a selection with a lasso tool, you can use filters to alter that part of the image without changing anything around it. This might be a good idea if you are trying to hide something in an image, remake it, or manipulate it. It’s also great for making photos more accurate. 

You can use your lasso tools to make a boundary for your filters. If you want to blur some rocks, for instance, but not the foot standing on top of the rocks, create a boundary around the foot so it won’t be affected by the clone stamp tool or blur filter. Inversely, want to create a bit of moss on the rocks, but not the foot? Use a selection tool to precisely place your greenery without worrying about any moss edging onto the skin. 

There’s a lot to know when it comes to the array of selection tools available in Photoshop, but knowing all there is to know about lasso tools is a great starting point.