Magnetic Lasso tool

If someone told you that in Photoshop you can select an object in a photo with 100% accuracy, and all you have to do is just draw a line around an object with a mouse, would you believe it? Not? And they would have done it right! This person only misleads you.

But if someone told you that there is a selection tool that can select an object, say, with 80-90% accuracy, and all you need is to draw a line around it at ease? Would you believe him then? No again? But this is already very bad, because there really is such a selection tool. And he is called Magnetic lasso (Magnetic lasso), and with a little practice and with an understanding of how this tool works, you will not only believe it, you will be obsessed with this tool.

Tool Magnetic lasso (Magnetic Lasso) – one of the tools of the group Lasso(Lasso) in Photoshop. Magnetic lasso (Magnetic Lasso) can be found in the group of tools Lasso(Lasso) in the toolbar. To understand where it is, left-click on the tool button. Lasso(Lasso) and hold it down, a drop-down menu will appear, then select the tool Magnetic lasso (Magnetic Lasso) from the list:

Magnetic Lasso tool

As soon as you select a tool Magnetic lasso (Magnetic Lasso), it will appear in place of the standard tool Lasso(Lasso) in the toolbar. For future use of the tool LassoTool(Lasso) or instrument Polygonal lasso (Polygonal Lasso), click on the tool Magnetic lasso (Magnetic lasso) and hold down the left mouse button until the drop-down menu appears again, then select either of the two other lasso tools in the list:

Magnetic Lasso tool

You can switch between lasso tools using the keyboard. Just hold Shift and press L several times to switch between tools (I note that you may not need to press the Shift key, it depends on what settings you have in Installations (Preferences) Photoshop).

Why the tool is named Magnetic lasso (Magnetic lasso)? So, unlike the standard Lasso tool (Lasso), from which there is no help, and it relies on your own ability to select an object with, as a rule, not very impressive results, the tool Magnetic lasso (Magnetic Lasso)edge recognition tool. This means that he is actively searching for the edges of an object while you are moving around it, then it clings to the edges of the selection and sticks to them like a magnet.
Does this mean that in reality Photoshop recognizes an object in the photo as soon as you try to select it? So of course it may seem in this case, but no. As we know, all Photoshop ever sees are pixels of various colors and brightness levels, so the tool Magnetic lasso (Magnetic Lasso) tries to compute the edges of an object by finding the differences in colors and brightness levels between the object you are trying to select and the background.

Best icon for the best selections
Of course, if the tool Magnetic lasso (Magnetic lasso) always had to view the entire image, while trying to detect the edges of your object, most likely it would not be able to do a very good job, therefore, for simplicity, Photoshop limits the areas where the tool searches for edges. The problem is that by default we cannot see how wide this area is, and this is because the mouse cursor of the tool Magnetic lasso (Magnetic Lasso) doesn’t really tell us anything. A small magnet allows us to find out that we have chosen Magnetic lasso (Magnetic Lasso), here he is:

Magnetic Lasso tool

To call a more useful icon, press the Caps Lock key on the keyboard. This action will switch the icon to the circle with a small cross in the center. The circle represents the width of the area that Photoshop sees to define the edges. He sees only the area inside the circle. All that is behind him, he ignores. The nearest defined edge is a cross in the center of the circle; Photoshop gives it the most importance when determining the location of the edges of your object:

Magnetic Lasso tool

Using the Magnetic Lasso tool (Magnetic Lasso)
Here is a photo of Chinese sculpture, which I opened in Photoshop. The edges of the sculpture are well defined, so I will try to highlight them by stroke with a standard tool. Lasso(Lasso). In any case, I can do this if I am looking for an excuse to pull my hair out of despair. The best option in this case would be to use the tool. Magnetic lasso (Magnetic lasso), because in the end he will do most of the work for me:

Magnetic Lasso tool

To start the selection with the tool Magnetic lasso (Magnetic lasso), simply place the cross in the center of the circle right on the edge of the object and click once, then release the mouse button. This will set the starting point of the selection. When you have determined the starting point, move the tool Magnetic lasso (Magnetic lasso) around the object, always keeping the edge within the circle. You will see that a thin line stretches from the cursor with which you move, and Photoshop automatically attaches it to the edge of the object, adding anchor points to fix the line in place. Unlike standard tool Lasso (Lasso), you do not need to hold down the mouse while you are circling an object:

Magnetic Lasso tool

To zoom in on the image while selecting the edges, press Ctrl ++ (Win) / Command ++ (Mac). Then press Ctrl + – (Win) / Command + – (Mac) to reduce. To scroll the image in the document window, when you zoom in on the image, hold down the space bar, which temporarily activates the tool Hand (Arm), then hold down the left mouse button and move the image to the side you need. Release the space bar when done.

Changing the width of the circle
You can adjust the width of the circle, which changes the size of the area in which Photoshop searches for edges using the option Width (Width) in the settings panel. If the object you select has clearly defined edges, you can use larger width settings that allow you to also move faster and freer around the object. Use smaller width settings and move slower around an object where the edge is not so well defined.

Magnetic Lasso tool

The only problem with the width parameter in the settings panel is that you have to set it before you start your selection, and there is no way to change it when you have already started selecting the object. The most convenient way to adjust the width of the circle is to use the left and right square bracket on the keyboard. This gives you the opportunity to adjust the size of the circle on the fly while working with the image, which is great because you often need to adjust the size, because you have to work with different parts of the image. Click the left square bracket ([) to make the circle smaller, or the right square bracket (]) to make it larger. You will see that the value of the parameter Width (Width) changes in the settings panel as soon as you press the keys, and you will see that the circle itself changes size in the document window:

Magnetic Lasso tool

Edge contrast
While the width of the circle determines the size of the area in which Photoshop searches for edges, the second and, equally, important parameter when using the tool Magnetic lasso (Magnetic lasso) is Edge contrast (Contrast edges). It determines how much a difference in the color or brightness value between the object and the background for Photoshop must be in order to consider an area as an edge.

You’ll find Edge contrast (Edge Contrast) in the settings panel to the right of the parameter Width (Width). For areas with high contrast between the subject and the background, you can use a higher value. Edge contrast (Contrast edge), respectively, with a large parameter value Width (Width) (large circle). Use lower value Edge contrast (Contrast Edge) and Width (Widths) for areas with low contrast between the subject and the background:

Magnetic Lasso tool

Like the parameter Width (Width), Edge contrast (Edge Contrast) in the settings panel can only be selected before the start of the selection, which does not make it too useful. To change it “on the fly” while working, press the dot key (.) On the keyboard to increase the contrast value, or use a comma (,) to decrease it. You will see the values ​​change in the settings panel.
Frequency
While you are creating a selection around an object, Photoshop automatically places anchor points (small squares) along the edge to anchor or snap a line to a place. If you find that the distance between the reference points is too large, making it difficult to keep the line attached to the edge, you can determine how often Photoshop should add reference points with the parameter Frequency (Frequency) in the settings panel, although, again, you need to set the value of this parameter before starting the selection. The higher the value, the more control points will be added, but usually, for good performance, the default value is 57:

Magnetic Lasso tool

Instead of changing the frequency, it is easier to simply add the anchor point manually when you need it. If it seems that Photoshop has problems keeping the line in the right place, just click on the edge of the object to manually add an anchor point, then release the mouse button and continue.

Error correction
If the pivot point was added in the wrong place, it does not matter if it was your fault or the fault of Photoshop, press the backspace (Win) / Delete (Mac) key on the keyboard to remove the last point that was added. If you continue to click Backspace / Delete, you delete the points in the reverse order of how they were added, which helps when the selection line starts to be applied unpredictably, as sometimes happens. Here, I completely missed the hair on this side of the sculpture, so I need to press Backspace / Delete several times to remove unwanted anchor points, then try to create them again:

Magnetic Lasso tool

This time, with a much smaller circle, I was more fortunate. Also adding some points manually helped:

Magnetic Lasso tool

If you are completely confused in the application of the tool Magnetic lasso (Magnetic lasso) and want to start over, press the Esc key to clear everything you’ve done.

Switch between Lasso instruments (Lasso)
Tool Magnetic Lasso (Magnetic lasso can often do an amazing job of selecting an object on our own, but it also allows us to freely switch to the other two Photoshop lasso tools if necessary. To temporarily switch to the standard tool Lasso (Lasso)or Polygonal lasso (Polygonal lasso), hold the Alt (Win) / Option (Mac) key and click on the edge of the object. All you have to do is determine which of the two lasso tools to switch to.

If you continue to hold the mouse button and drag it, the standard tool will turn on. Lasso (Lasso), so you can draw a selection of arbitrary shape around the area where Magnetic lasso (Magnetic lasso) there were problems. When you’re done, release the Alt / Option key, then release the mouse button to return to the tool. Magnetic lasso (Magnetic lasso).

If you release the mouse button after pressing the Alt / Option key, while holding the key, move the mouse cursor away from the point, by clicking the mouse, you will switch to the tool Polygonal lasso (Polygonal lasso), which is convenient for highlighting straight sections of an object. Hold down the Alt / Option key while clicking, from point to point, to add sections with straight lines. To switch back to the tool Magnetic lasso (Magnetic lasso) when ready, release the Alt / Option key, then click on the edge of the object to add a point and release the mouse button.
I want to include the stand on which the sculpture is installed in my selection, and since the edge of the stand is straight, I will temporarily switch to the tool Polygonal lasso (Polygonal lasso):

Magnetic Lasso tool

Close selection
Once you have made your way around the object, click on your starting point to complete the selection. When you get close enough to the starting point, you will see that a small circle appears below the right of the cursor icon, allowing you to understand that you can now close the selection:

Magnetic Lasso tool

And after that the sculpture is highlighted:

Magnetic Lasso tool

Remove area from source selection
After I studied the photo more carefully, I noticed that the sculpture has a small space with a background between the side of its body and the hand on the right:

Magnetic Lasso tool

I need to remove this section from the selection. To do this, with the active tool Magnetic lasso (Magnetic Lasso), I hold down the Alt (Win) / Option (Mac) key, which temporarily switches me to Subtract from selection (remove from selection). A small minus (-) icon will appear in the right corner of the cursor icon, allowing me to determine that I am near the part of the existing selection to be deleted:

Magnetic Lasso tool

While holding down the Alt / Option key, I click once to set the starting point, then I release the mouse button and walk around the edge of the section to be deleted. As soon as I start the selection, I can release the Alt / Option key. At this time you do not need to hold it down. Photoshop saves me in mode Subtract from selection (remove from object) until I click on the original point to complete the selection. I will press the Caps Lock key again to switch to the circle icon, since this is how I can clearly see where Photoshop is looking for edges:

Magnetic Lasso tool

As soon as I made my way around the space, I click on the original point to close the selection, removing the unwanted area.
Only the sculpture itself with the stand on which it is installed remains highlighted:

Magnetic Lasso tool

With the sculpture I just selected, I can later do something, and this will only affect the sculpture. The remaining sections of the photo will not be affected. For example, I can press the M key on the keyboard to quickly bring up the tool Move, then I will click on the sculpture and move it to the second image I opened to create another background for it:

Magnetic Lasso tool

Remove selection
When you’re done with the selection, and you no longer need it, you can delete it by going to the menu Select (Highlight) on the top of the screen and select Deselect (Remove selection), or you can press the keyboard shortcut Ctrl + D (Win) / Command + D (Mac) on the keyboard. Or for a quick way to remove a selection, just click anywhere inside the document with a tool. Magnetic lasso (Magnetic Lasso) or any other selection tool.

Tool Magnetic lasso (Magnetic lasso) is undoubtedly one of the best selection tools we have for working in Photoshop, which gives us a much better result than we can get using a standard tool. Lasso(Lasso), in less time, with less effort and frustration. Be that as it may, he needs a little practice with the parameters Width (Widths) and Edge contrast (Contrast of the region), before you speak to him on “you”, as with most things in life, he is not perfect.

For best results, use the tool. Magnetic Lasso (Magnetic lasso) is a good way to start a selection, as it usually does 80-90% of the work for you. Swipe tool Magnetic lasso (Magnetic lasso) around the object once, creating its own selection, then zoom in and look carefully at the selection area to find the areas where the tool Magnetic Lasso (Magnetic Lasso) worked badly. Use standard tool Lasso (Lasso) to enable mode Add to selection (Add to selection) and Subtract from selection (Remove from selection) to fix any problems. For a more detailed understanding of how to do this, study the work of the standard tool. Lasso(Lasso).

Posted by: Steve Patterson
Translation: Alexander Antsiperovich
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