What Deep Fusion is on iPhone 11 and how to make sure it's working

iPhone 11 Pro one hand zoom on camera
iPhone 11 Pro one hand zoom on camera (Image credit: Christine Romero-Chan / iMore)

Apple announced Deep Fusion at the September iPhone event this year, but it did not launch in iOS 13 with the iPhone 11 and iPhone 11 Pro models. It is, however, now available in iOS 13.2 on iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max.

While Deep Fusion happens automatically and won't be noticeable like Night Mode, it turns out that it won't be enabled if you have the Capture Outside of Frame setting turned on (here's how to enable Capture Outside of Frame if you missed it). So if you have Capture Outside of Frame turned on, Deep Fusion will not be available, and vice versa.

What is Deep Fusion and how does it work?

iPhone 11 Deep Fusion sample

iPhone 11 Deep Fusion sample

Deep Fusion is a new computational photography process specifically on the iPhone 11 line because of the A13 chip. It blends together multiple exposures at the pixel level in order to create a photograph with an even higher level of detail than standard HDR. This means even more detailed textures in things like skin, clothing, and foliage.

Unlike Night Mode, Deep Fusion will happen automatically and we won't even notice it. However, it will only activate in certain situations.

With the Wide (Normal) lens, Deep Fusion kicks in at just above the 10 lux floor that triggers Night Mode. Whether Night Mode or Deep Fusion activates depends on the lighting source for the current scene. On the Telephoto camera, Deep Fusion will be active in pretty much everything except the brightest situations, as that is when the Smart HDR goes into effect due to the abundance of highlights.

Essentially, Deep Fusion has the camera shoot a short frame at a negative EV value. This results in a darker image than you would normally like, but it just pulls sharpness from this frame. It also shoots three regular EV0 images and then a long EV+ frame, aligns everything together, and blends all of the images into one.

You end up with two 12MP images that are combined together in a single 24MP photo. The process to do this uses four separate neural networks, which account for all of the noise characteristics of the camera sensors, as well as the photo subject matter.

The machine learning process looks at every individual pixel before combining, and it only takes about one second to process everything. Deep Fusion will happen in the background, and you'll never really notice it until you see the images it produces.

What is Capture Outside of Frame?

Capture Outside of Frame is a setting available on iPhone 11 and iPhone 11 Pro that lets you capture content outside of the frame on the viewfinder. This captured content only appears when you make edits to the photo, such as cropping, straightening, rotating, and adjusting perspective. For QuickTake video capture, it helps improve the composition.

So why won't Deep Fusion work with Capture Outside of Frame?

Deep Fusion sample

Deep Fusion sample

The Capture Outside of Frame feature works by utilizing the Ultra Wide camera to capture the rest of the scene outside of the frame. However, Deep Fusion does not work with the Ultra Wide camera due to the lack of focus pixels and optical image stabilization (this is also why Night Mode does not work with the Ultra Wide lens).

So if you want to compare how effective Deep Fusion is, take a picture with Deep Fusion on, and then turn on Capture Outside of Frame and take the same photo.

Any questions?

Do you have any questions about Deep Fusion or how it works? Let us know in the comments!

Christine Chan

Christine Romero-Chan was formerly a Senior Editor for iMore. She has been writing about technology, specifically Apple, for over a decade at a variety of websites. She is currently part of the Digital Trends team, and has been using Apple’s smartphone since the original iPhone back in 2007. While her main speciality is the iPhone, she also covers Apple Watch, iPad, and Mac when needed. When she isn’t writing about Apple, Christine can often be found at Disneyland in Anaheim, California, as she is a passholder and obsessed with all things Disney, especially Star Wars. Christine also enjoys coffee, food, photography, mechanical keyboards, and spending as much time with her new daughter as possible.