How to Blur the Background of a Portrait Using the Magnetic Lasso Tool in Photoshop


Have you ever taken a portrait and wished that the background were just a little bit more blurry? You can address background blur in-camera by changing either your aperture or the distance of your subject from the background. However, there’s also a relatively quick way to make slight adjustments to background blur in post-processing. In this article, we’ll be walking through how to use the Magnetic Lasso tool in Photoshop to slightly blur the background of your portraits and people photography.

Getting started

First, open your desired image in Photoshop, and duplicate your background layer (Layer > Duplicate Layer). Next, select the Magnetic Lasso tool. If you’ve not used this tool recently, you may need to right-click on the original lasso tool and then click on the magnetic lasso tool from the fly-out menu.

How to Blur the Background of a Portrait Using the Magnetic Lasso Tool in Photoshop

Selecting the subject

Using the Magnetic Lasso tool, begin by clicking at any point right next to your subject. You’ll notice that the magnetic lasso tool begins to “stick” to what it thinks is the outline of your subject. Continue to click your mouse to create anchor points periodically all around your subject.

If the magnetic lasso tool jumps somewhere you don’t want it to go, press the delete button on your keyboard to return to your last anchor point.

How to Blur the Background of a Portrait Using the Magnetic Lasso Tool in Photoshop

Definitely be aware that once you’ve started using the Magnetic Lasso tool, you’re pretty committed! You won’t be able to do much else with Photoshop until you’ve either completed the lasso loop by connecting your endpoint to your starting anchor point or until you hit “Esc” on your keyboard to delete all your anchor points.

Once you’ve closed your lasso loop, navigate to Select > Modify > Feather (or Shift + F6) and feather your selection by 5-10 pixels.

How to Blur the Background of a Portrait Using the Magnetic Lasso Tool in Photoshop

Feather your new selection 5-10 pixels.

Invert to select the background

Next, you’ll want to invert your selection so that you’ll be blurring the background rather than your subject. To do that, navigate to Select > Inverse (or Ctrl + Shift + I). If you see a dashed outline appear around the border of your image, then you’ve correctly inverted your selection.

How to Blur the Background of a Portrait Using the Magnetic Lasso Tool in Photoshop

Notice where the marching ants are – if they appear like this around the outside of the image you’ve correctly inverted the selection.

Adding the blur effect

After you’ve inverted your selection, it’s time to blur the background of your image. Click on Filter > Blur > Gaussian Blur. Next, play with the radius slider a bit.

Please keep in mind that this technique isn’t designed to take a tack sharp background and transform it to the creamy bokeh of an 85mm lens. Rather, it’s designed to slightly enhance the bokeh that you’ve already got going on in your image. As such, I usually select a radius of 5-10 pixels for the blur filter.

Don’t be afraid to play around with this a bit. Utilize the preview check box, and see what your image looks like when using different amounts for the radius!

How to Blur the Background of a Portrait Using the Magnetic Lasso Tool in Photoshop

Gaussian blur added.

Finishing up

Once you’ve run the Gaussian Blur filter, press Ctrl + D to deselect your image, and you’re about finished! If there are any parts of your image that are blurry and shouldn’t be, go ahead and add a layer mask to your top layer, and mask off any of those blurry areas, and then you’re finished!

How to Blur the Background of a Portrait Using the Magnetic Lasso Tool in Photoshop

Original image on top; image blurred with magnetic lasso tool on the bottom.

As you can see, this technique is subtle, and helps to soften (but not eliminate) slightly distracting elements from the background of your image. I most often find myself using this technique on one or two person portraits, including newborns. It’s a really simple trick to have in your tool bag!

Have you ever utilized the magnetic lasso tool for people photography? What’s your favorite way to use it? Chime in below and tell us in the comments section.

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Meredith Clark is a wife, mother, native Oregonian, complete bookworm, Top Chef lover, and new quilting addict. She believes that photography is for everyone - it is a gift that allows us to capture and document both ordinary and extraordinary moments in our lives. You can see more of her work at Meredith Clark Photography or connect with her on Facebook.

  • Walter Pinkus

    It appears that you didn’t blur the background that can be seen between the mother and baby. I would take that as a dead giveaway that manipulation has been done, spoiling the effect. Otherwise, a well-done tutorial. Thanks.

  • Meredith

    Hey Walter,

    When using this technique, you can certainly hit any areas between people with the blur tool as needed according to your personal preference.

  • I hate fake blur with a passion. And while the images you show here are small enough to almost hide the reasons I hate fake blur, the evidence is still there.

    Look where the background meets the mother’s hair on the back edge. Her hair is no longer as sharp as it used to be. And if it were, then the background behind it would also be sharp. Or look where the edge of her hand holding her baby meets the background. Her fingers and ring are no longer as sharp as they used to be. And if they were, the background would be sharper there – spoiling the blurred background effect. The same goes for where the blanket meets the edge of the blurred background – suddenly the blanket is no longer as sharp as it used to be.

    And sure, at this size, it’s very hard to notice this. But try printing the image as a 16×24 and these little spoilers become VERY noticeable.

    If you want blurred backgrounds, use a wider aperture (smaller number). Do it in camera and forget the fake background blur, it’s not worth the loss in quality.

  • Meredith

    Thank you for sharing your opinion David. It sounds like this particular tutorial isn’t the best fit for you and your style of photography.

  • You are correct that the tutorial isn’t a fit for me at all. The reason for my post was to help others see why it’s not a good fit for them either. If they care about the quality of the results – especially if they are going to print the image – then they’ll regret considering fake blur when they see the results.

  • Meredith

    David, I can guarantee you that there are photographers of all levels that add blur in post processing just as there are photographers of all levels that never do. There really aren’t *any* aspects of photography that are universally right or universally wrong. It’s okay that this particular technique isn’t your cup of tea, but there’s no need to suggest that photographers who use this technique don’t care about the quality of their images.

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