Smartphones and Depth Maps

August 19, 2018

I’m taking a break from the intensity of reviews and delving into computational photography and how it can be used on your phone to create anamorphic-looking results.


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Hey folks! Tito Ferradans here for a different subject. I recently picked up an iPhone 8+ because of its dual camera. The dual camera is the secret to Portrait mode – where the phone uses info from both cameras to simulate depth of field and subject separation through math and software.

Portrait mode by itself is not that impressive since it gives you very little control over the final result – just kidding, it’s still pretty impressive -, but it sets precedent for much more interesting apps. The way Portrait mode works is when you take a photo, the phone uses information from the two cameras (which have different placement and focal lengths, displaying parallax between them) to create a depth map. This is a black and white image in which objects closer to camera show up brighter and fade into black as they get further away – this matches the regular photo we just clicked.

Through the use of this depth map, software is able to break a 2d image (the photo) into layers in 3d space and process that data simulating a real camera with a real lens and aperture. The original image has extreme depth of field (tiny sensor, wide lens) so nothing is out of focus, and the depth map allows you to pick where you want focus to be, while blurring the rest like a big sensor would. This by itself is also no big breakthrough, Hollywood has been doing it for years with CGI. Having it on the palm of your hands is where the paradigm shifts. Now you don’t need exclusive software, dozens of specialists and powerful 3d apps to manipulate depth of field realistically in post.

It didn’t take long for app developers to jump in and take advantage of the depth map to turn dual camera photos in something much more interesting and controllable than Apple’s Portrait mode. On upcoming episodes I’m gonna talk about the apps Depth Cam and Portrait Cam as well as Focos – which add their own spin to anamorfaking in post. I’m stopping this one here because I think there’s enough post-production theory enough. This has big implications on how the anamorphic look can be achieved on a budget – even if just for stills.

If you wanna go further down the rabbit hole of smartphone cameras, take a look at how the Google Pixel 2 creates a similar effect using a single camera instead of Apple’s two cameras. For now, let me know your thoughts in the comments below about this parenthesis among all the anamorphic talk! Subscribe to the channel to be notified when the app reviews come online and like this video if it made sense to you! Lastly, I highly recommend making a pledge at my Patreon page because this stuff is not gonna be free forever. With more money comes more quality and better tools! See you tomorrow. Tito Ferradans out.