Background blur, often called “bokeh” after the Japanese word for blur, is generally associated with high-end cameras with wide-aperture lenses. The effect is popular for portraits, and is emulated — with some limitations — by the “portrait modes” now found on many smartphones. But even without a high-end camera or portrait mode, you can still create beautifully soft backgrounds in Adobe Photoshop.
Beyond simply granting you an ability you may have not had access to in camera, choosing to add blur in Photoshop can give you more control and flexibility over where the blur is applied and how it looks. The program includes a number of different tools to selectively blur the background of a photo, along with many options for controlling the type of blur. One of the easiest ways to go from blah to blur, however, is by using Photoshop’s field blur tool, which creates realistic background blur without requiring you to waste hours in front of your computer.
Hillary Grigonis / Digital Trends
Hillary Grigonis / Digital Trends
Before you get started
Photoshop includes a handful of different options to blur a background, with each option offering a varying level of control — and level of difficulty. After trying everything from detailed selections to a full-on depth map, the field blur tool offered the best, most realistic results in the least amount of time.
Bokeh is a tricky thing to try to imitate in Photoshop because true lens blur is based on many factors, including the focal length of the lens, the shape and size of the aperture, and distance from the subject. Of these, getting the effect of distance correct is perhaps the most important. In Photoshop, you have to tell the computer what objects are closest and farthest from the camera in order to get a blur that resembles the real thing and changes with distance — i.e., objects that are farther away from the subject should have more blur than objects that are closer. You could spend an hour creating a detailed depth map, but the field blur tool lets you approximate this with much less work.
We should note, Photoshop techniques are almost always more work than getting the effect in-camera, but the field blur tool will quickly imitate the bokeh of a more expensive lens. As you work, consider how the blur in a real image looks. A lens focuses on a tw0-dimensional plane in space, with everything on that plane being sharp. The level of blur increases with distance from the plane of focus — that is, either toward or away from the camera — but any objects that fall on the same plane as your subject should remain in focus.
How to blur a background in Photoshop
1. Open up the field blur tool.
With the image open in Photoshop, navigate to Filter > Blur Gallery > Field Blur. Inside the field blur window, you will choose what areas of your image to blur, while the blur tools on the right will control the amount and type of blur.
2. Set your first blur pin.
The blur pins tell Photoshop where to blur and how much. When you opened the field blur window, Photoshop automatically placed that first pin for you. Drag and drop that pin into the background, or the area the farthest from the focal point. On the right, drag the blur slider until you achieve the desired amount of blur. (You can also change the blur amount by clicking and dragging on the partial circle outside the pin.)
Since this first pin is the furthest point from the focal point, this pin will have the most blur. In the sample image, I used a blur of 100, but the numbers will vary based on the effect your are looking for. You can always go back and refine the blur of any pin simply by clicking on it.
3. Set a blur pin on the subject at zero.
When you first open the field blur tool, your entire image will be blurry. Set a pin directly on top of the subject by clicking on it, then dragging the blur slider all the way down to zero. You should now have a generally blurry background and a generally sharp subject.
Continue to place blur pins on the subject, setting each at zero, until the entire subject is sharp. Use as few pins as possible, but don’t worry if the background appears more sharp as you place pins.
4. Continue to refine the blur.
At this point in our sample image, the horse’s face was sharp and the background was blurred — but the rest of the horse’s body was just as blurred as the background. To fix this and achieve a more natural result, simply add more pins. Adjust the blur based on the distance from the original background point — objects closer to the background should have a blur closer to that original point (closer to 100, in our case) while objects closer to the subject should have a much lower level of blur (closer to zero).
Continue placing points and adjusting the blur until you every part of the image is blurred based on the distance from the subject. If this starts to interfere with the background blur, don’t worry — just place additional background points to ensure the background remains properly blurred. In our sample image, the background just to the left of the horse’s face was still a bit sharp, so we added another point there, setting it to the same blur value of 100.
5. Adjust the blur effects, if necessary.
Once you are happy with the placement and level of blur on the different distances in the image, you may (or may not) want to use the blur effects options, depending on your image. Here’s what each one does:
- The “light bokeh” control will brighten the brightest points in the out-of-focus area to mimic lens bokeh. Avoid these controls if you don’t have point lights in the background. “Bokeh color” will adjust the color of those bright areas, while “light range” will adjust what tones are included in the bokeh effect.
- The noise tab will restore any blurred noise in order to get the background to match the subject. If you are working with an image shot at a high ISO, for example, you’ll need to use this option so that the subject doesn’t have more noise than the background, which would look unnatural. Use the sliders to change the amount and the size of the grain to best match the grain in the subject. If there simply wasn’t any noticeable noise in your original image, you can leave this setting untouched.
Once you are happy with the level of blur, bokeh effects, and noise, click OK, and Photoshop will render the effect.
There are a number of of other ways to add blur in Photoshop, but the field blur tool is a great place to start. It offers flexible, realistic effects without requiring complex masks and depth maps.
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