One question that comes up more than most, especially from users of compact digital cameras, is how do I create a depth of field effect on my photos using Adobe Photoshop?
As with many photo enhancing techniques the key to getting good results is not using a complicated method, but in taking the time to make accurate selections and layer masks.
We’ll cover ways in which you can try and minimise the depth of field of your shots using just the features of your digital camera in a future tutorial, but for now we’re going to concentrate on mimicking the effect using software (in this case Adobe Photoshop CS4).
Creating the Desired Effect
This is a photo of a friend I took last year using my Fuji Finepix F50fd digital compact. I really like the soft lighting and relaxed natural look of this shot, but the child in the background is quite distracting.
By blurring out the background we can eliminate this distraction, but we want to do so in a way that looks realistic and not too artificial.
To do this we’re going to use the Lens Blur filter (note that this filter is only available in the full version of Photoshop, and not Photoshop Elements).
As is always best practice, duplicate the background layer by pressing Control-J (or Command-J on a Mac)
This means you can always easily compare your modified image with the original, and ensures that if you change your mind about the changes you’ve made there’s a safe copy you can revert back to.
Using the Quick Selection Tool, click to create a selection of the area that you want to become blurred. If this isn’t practical then you can select the area you want to keep in focus, and then click Select – Inverse to invert the selection.
If you select an area that you didn’t intend to, then you can de-select it by holding down the Alt key and going over the area again. You may want to start with a large brush to select the bulk of your background and then use a smaller one to complete an accurate selection around your subject.
It’s worth spending the time getting your selection right here, as a rough selection at this stage will give poor results later.
This is how our example looks with the background selected.
Once you’re happy with the selection, create a mask by clicking the Add Layer Mask button in the layers palette.
Duplicate the background layer again. Your layers palette should now look something like this.
With the masked layer selected, apply the Lens Blur effect by clicking Filter – Blur – Lens Blur.
The lens blur option gives the most realistic effect of all the blur options, but may take a while to render on some computers.
There are numerous options in the Lens Blur dialog, but to illustrate this effect we will only adjust a couple.
Firstly, we need to set the Source in the Depth Map section to Layer Mask.
Next, under Iris we need to set the Radius. This will depend on both how much blurring you want and how large your original image is – for this example I chose a radius of 60 (my original image was approximately 2800 x 2100 pixels), but you should adjust this with the preview mode enabled to find something that looks right for your shot.
We’re now at a point where the image is acceptable and the busy background is no longer distracting. If this works for you then you can stop here, though there are still a few tweaks we can make.
Advanced (optional) Steps
Looking at this example, the picture would benefit from a subtle gradual blur as the legs go into the background.
If we go to the Channels Palette and make the layer mask we created earlier visible, then we can adjust the mask by hand.
Take a large eraser brush (exactly how large will depend on the size of your image), set the hardness to 0 and opacity quite low (around 20-30%), then gradually go over the areas you want to partially reduce the focus of.
Trial and error maybe the key here, but don’t overdo it. This is what my mask looks like at this stage.
And there we have it – you can play with the settings in the lens blur dialog and take more time over the selection as you wish. You may also choose to blur some of the foreground objects to create a shallow depth of field that leaves only the subject in focus.