By Graham K. Rogers

One of the really nice features on the iPhone 7 Plus is Depth Effect: photographs with the subject in sharp focus and a blurred background. Depth Effect was not available when the iPhone 7 Plus was first released, but was added some time later in an update. The effect comes from using the two lenses and from software. This type of output can be quite pleasing. The user has two versions of the image: one with the effect and one without.

Those with the iPhone 7 or earlier versions of the iPhone are out of luck, but I found a software solution for this effect when I was digging through the App Store this week in search of more apps for my Why haven't I seen this Before category. Using Bokeh Lens, takes a similar approach to those apps that produce the Tilt-Shift effect that can make landscapes look like models. It may need some deft finger work, but if I can manage, there is something to be said for this 35 baht ($0.99) app.

Although sourcing images for the app uses a Camera icon, and the camera is available, I prefer to use Photo Library input. When an image is selected, it is displayed on an editing screen with four main icons at the bottom of the panel: Edit Focus, Adjust, Compare and Settings. This last item provides access to Help, App Support, Rate & Review, and About.

Guides (for example, Start Here) are provided but the app is simple enough that they can be ignored. I tried a couple of images: one that I had taken using the Depth Effect; and one without. I wanted to compare the Bokeh Lens version with the Depth Effect version. The different outputs are close, but Bokeh Lens also provides additional adjustments.

When an image is imported for use, the Edit Focus tool had the choice of a brush to mask the image and an eraser to remove the mask (or parts). A slider allows the brush/eraser size to be adjusted, but the Pinch can be used too so that the effect can be more easily fine-tuned. When this is done, and the finger is placed on the image (either brush or eraser) a useful zoom window appears at the top of the screen with a spot to indicate the exact location of the brush. This makes it easy to edit the image exactly and I found this a really helpful feature.

Once masking is complete, the user presses Done (top right). There is a brief processing time and the image, with its focussed subject and blurred background is shown. It is possible to return to the Edit Focus panel as many times as is wanted to continue making adjustments. Adjust provides two sliders: Bokeh Level and Mask Feather. With the two used carefully, a good effect is possible. However, too much Bokeh can mar the finished result, making it look unrealistic. The compare icon provides a quick look at the original.

At top right of the screen is a yellow Export icon for Save Image or Share (Message, Mail, social networking et al, depending on the user's setup). Using one image that was 4032 x 3024 and 2.68MB in its original JPG form, output was the same dimensions with a reduced file size of 1.35 MB. There was no camera metadata or GPS information as there had been with the original. I did take one photograph with the app. No metadata was included either with the original image or the edited version. The dimensions stayed the same but (again) file size was reduced.

Bokeh Lens Output from iPhone 7 Plus

Although Bokeh Lens is not optimised for the iPad, it seemed that applying the mask would be enhanced by use of the Apple Pencil. I had to adjust the slider right down to the smallest brush radius, but was able to edit more accurately (as I had expected) with my fingers than on the iPhone. For some of the fine work, it was better to enlarge the screen and use the zoom window making accuracy easier to achieve. With the Apple Pencil, this is all much easier. Unlike the iPhone, dimensions of the output image as well as file size were decreased.

Bokeh Lens Output from iPad Pro (left) and iPhone SE

The Bokeh Lens app might appear to be redundant on the iPhone 7 Plus, but since the feature has been available, I have taken several photographs that the Depth Effect does not work with, mainly due to distance from the subject. In these cases, if wanted, the effect can be applied using Bokeh Lens (or other similar apps) and the original image is retained.

For those with the iPhone 7 or earlier models - I also tried this on the iPhone SE with some good results - this is an inexpensive way to produce some useful Bokeh on photographs. This is highly recommended.

Graham K. Rogers teaches at the Faculty of Engineering, Mahidol University in Thailand. He wrote in the Bangkok Post, Database supplement on IT subjects. For the last seven years of Database he wrote a column on Apple and Macs. After 3 years writing a column in the Life supplement, he is now no longer associated with the Bangkok Post. He can be followed on Twitter (@extensions_th)