This week I have made a really fun and useful tutorial that not only gives you great results, it will also teach you a little bit about channels. Don’t worry, they aren’t as scary as they sound. This Photoshop tutorial shows you how to blur the background of a photo to add a realistic depth of field by using Depth Maps, or blur masks as they are sometimes called. This method allows you to add a different amount of blur on different parts of the photo.
The photo used here
In this Photoshop tutorial, you will learn how to blur a background to simulate depth of filed from a nice expensive lens. You have heard the term bokeh, or depth of field or background blur. This all comes from a large opening in the lens that throws the background out of focus. Maybe you don’t have that lens, or couldn’t open the aperture because of too much light, or you used a drone, a GoPro or a phone. Or maybe you just want to have that control yourself in Photoshop. We will use masks to control where and how much of a blur will be applied to a photo. This allows you to create a very realistic depth of field effect that add depth as well as simplifies the composition of an image and makes it more pleasing.
Choose the Quick select tool.
Choose select subject, or use the quick selection tool to select our woman.
Choose Select and Mask to refine the selection
First we will make the edges nice, automatically.
Turn on show edges
Adjust the amount slider until you can just see the edges.
Turn show edges off again
Choose the refine brush and go around the edges of the hair to get a better selection.
Choose Selection as the output option and click ok
Now you have a selection around our woman,
Click on the new Layer icon in the Layers panel to create a new layer.
Fill the selection with black on the new layer. (Press D to reset the color and use Option+Delete (Mac) Alt+Backspace (windows) to fill.
Press Cmd/Ctrl+D to deselect
Choose the background layer in the layers panel
Grab the quick select again. This time select the ground near our traveller. Use the alt/option key to remove from a selection if you went too far.
Choose select mask
Turn on show edges
This time make the outline thicker
Turn off Show Edges
Use the refine tool to clean up the selection around the bush
Click ok
Make a new layer
Choose 40% gray as the foreground color
To get 40% gray, click the color swatch. 
Choose black, and then under HSB, change the B to 40 (B is for brightness).
Press Cmd/Ctrl+D to deselect
Fill the selection with 40% gray
Hide the background, so only the black and gray layers are showing.
Press Shift+Cmd+Option+E (Mac) Shift+Ctrl+Alt+E (Windows) This will create a new layer on top that contains the content from the 2 visible layers.
Hide all the layers except for the new merged layer we made in step 13.
Press Cmd/Ctrl+A to select all
Press Cmd/Ctrl+C to copy
Open the Channels panel
Click the new icon to create a new Channel (alpha 1)
If the channel is black, press Cmd/Ctrl+I to invert it and make it white
Press Shift+Cmd/Ctrl+V to paste in place. (The Shift key makes it paste in place)
You should see a black foreground, gray midground and white background. This is our mask, or depth map
Click on RGB at the top to make sure that the RGB is selected and showing and the eye next to the Alpha channel is off. (If it looks red, you haven’t done this step correctly, look at the screen shot carefully)
Go back to the Layers panel and hide everything except for the background which is our image. Click on the background to make it active.
Press Cmd/Ctrl+J to duplicate the background, this gives us a safety layer.
Choose the duplicated background layer if it’s not already selected. This is where we are going to apply our effect.
Choose Filter>Blur>Lens blur
Change the blur amount to add more blur to the photo. The problem is, everything blurs.
Here is the key.
Under Source at the top, choose alpha 1 (our map) for the dropdown menu.
Now it should protect our woman in the foreground and apply the full blur to the background.
Something interesting happened in the mid-ground where we made it gray. It only blurs 40%. the same percentage as the shade of gray. This means that the amount of blur is directly proportional to the shade of gray used.
Click ok to apply
This is just a simple example of how this effect can be used, with 3 level of blur. You can use gradients or multiple shades of gray to build up a very complex blur mask if you put the time in.
I really hope you enjoyed this week’s tutorial here at PhotoshopCAFE.
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Great tutorial ! One suggestion it would great to have a the sample file to follow along with.
Shooting with a Canon EOS SL1, It’s a great camera with a small body which makes for very convenient travel. The crop sensor may be a problem for some, but you learn to make the appropriate adjustments for good composition.
Thank you for another great tutorial. They are always helpful and so clear.
excellent tutorial! I use a Light16 camera now – almost entirely. Love it. Export their Lumen RAW to DNG.
Great tutorial as usual Colin.
The camera I am using at the moment is the Fujifilm X-H1.
Great tutorial, I use a D500
What camera? Well, way long ago used to use a variety of film cameras. Then moved to Canon Rebel XTi with several lenses. Then went down to Rebel SL1 with one compact lens. And now, I’m totally smartphone – Android Galaxy S6 with 16 megapx. Produces very decent photos when used with a Gorilla Pod or a standard tripod. And great video for informal podcasts, etc. How the world has changed!
Thank you , very interesting
Canon D50 EOS
Just moved from a Canon 7D MII to Oly EM1-X – the weight difference of the lenses and the 7.5 stop IBIS make it a remarkable upgrade.
Great video – Presumably this approach could use several levels of grey/depth?
Canon D7
Colin, I’m finding out more and more people are using their iPhone or Android as their shoot/click camera. I recently bought a Smooth 4 gimbal for the Note 9. It is a miracle in design engineering, features and mobility. What it isn’t is easy to use. It is highly demanding you pay attention to the available tuts. Many of them are crap but there are a few that are just stellar. Recommend using the ZY Play downloaded from Google Play. It’s just fantastic esp. for time lapse and slow mo. Get it from Amazon as they are amazing about returns. I had an issue with the first one and, before I even took it to UPS for return, I had received the replacement – no shipping charge. So, I heartily recommend the Smooth 4 for iPhone/Android.
Great tutorial Colin. Nikon D7000
Pretty cool! I didn’t know about the depth map option in the blur filter! One learns something every day.
I’m using a Nikon D810 for a couple of years now.
Use a Sony A55. I like the it feels and the sharpness of the pictures it takes.
Mr. Smith, I taught graduate and undergraduate students for 35 years. I can really appreciate the amount of effort it takes to continually have to think of new ideas for presentations. Then, to have the teaching skills to put a presentation together with video, audio and written procedures is truly impressive. And this effort is without direct financial rewards. It all comes down to teaching as a passion which is only partially rewarded by “student” expressions of thanks in the replies. As a 74 year-old continual student, I just want to say how deeply I appreciate your mind, skills, effort and passion.
Thanks so much for the nice note, made my day!
Hi Colin, I have enjoyed your tutorial but have a snag. Using PS 2019 and the “lens blur” is greyed out. Have tried several ways including open the file in RAW to no avail. Any ideas?
PS. I am using your image of the girl
Nifty tutorial, you are the master. Current camera Fuji X-t2.
Thanks for the tute Colin. I use a Nikon D500.
Nikon D850. Nice tutorial, thanks
Nice tutorial, thanks. Nikon D850
Canon 5D Mark IV
Handy tutorial but something from the comments occurs to me that I wonder about…should we be caring what camera everyone is using, or is that more of a “look at me” sort of thing?
Its useful to know what brands people are using, so I know what reviews to do in the future, I don’t thank anyone is seeing it as bragging thing.
Pentax K1 & prior to that various Pentax DSLRs and analogue cameras.
I use a sony rx10MK3
Great tutorial! I love the variety of lessons that you put up. I came back to this one the other day to do a test on a photo I took of a bird. It worked! I use either the Sony A7 III or a Sony A7R III primarily.
Great article! I really need to break down and buy photoshop instead of editing only through Lightroom 🙁
Easy to follow tutorial. Thank you Colin.
Although I am having the same problem as David above where I cant use the lens blur? Using PS 2019
My camera is a Canon 5d mk4
I Don’t see Davids comment. Where is it not working for you? Which step?