On this video Photoshop expert Jesús Ramirez (from the Photoshop training channel) looks at two useful ways to blur backgrounds in Photoshop.
When at all possible we always recommend achieving the result that you want in camera and that includes blurring the background. However, this isn’t always possible – either since you used the wrong lens (or didn’t have one) or from any other technical reason. In this case, you might still be able to blur the background using Photoshop and this video might help you with that.
This video is rather long so it is divided into a number of parts:
00:36 – Blurring Backgrounds With The Tilt-Shift Blur
07:07 – How Values Relate To Depth
08:42 – Creating a Depth Map
13:25 – Depth of Field Effect Using The Lens Blur Filter
18:43 – Depth Maps with Adobe Dimension
You will start by selecting your subject and inverting the selection so that you will blur just the background. Ramirez starts with the tilt-shift effect. One interesting tip here is that after you are done you can add grain to your blurred selection to make it match your subject (you can do this in the Camera RAW filter). There is much more in this video of course and you should check it out with Photoshop open and try some of the methods for yourself.
We have looked at this topic in the past in a video by Tony Northrup entitled “How to Create a Blurred Background with Photoshop” as well as an older video back in the days of Photoshop CS6 (on this video).