(Credit: Indice Ltd)

In 2016, the iPhone 7 wasn't a major change like the X series, but there were some notable additions and removals. Apple removed the headphone jack, controversially citing "courage" as its motivator, but it also added a second camera lens to the back of the device. One of the chief advantages of this tech is Portrait Mode, because it can realistically blur the background when you're taking a picture of someone -- and a third-party developer figured out a clever use for it.

Portrait Mode uses the depth sensing of an iPhone's secondary lens to figure out what part of a photo to blur, and Apple makes this math available for iOS developers. The makers of Apollo: Immersive Illumination use that math not for blurring but for figuring out how to add and tweak light sources that were not present at the time the picture was taken. Sounds pretty neat, right? How many selfies can you think of that were ruined by bad lighting?

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In case the app's regular price of $1.99 was too rich for your blood, Apollo: Immersive Illumination is currently on sale for just 99 cents. And there are no in-app purchases or subscription fees to wrestle with. Just fork over about a dollar, and you're done.

If the original picture wasn't lit the way you liked, the Apollo app can add up to 20 simulated light sources and let you adjust them within the "scene" as though it were a three-dimensional space. You can tweak brightness, distance and size; choose from different colors; and add shadow patterns between the light and the subject, like multi-paned windows or tree branches.

According to the developer, Apollo: Immersive Illumination is the only app that can add light sources to a Portrait Mode photo after the fact. It does this by way of a "proprietary processing algorithm."

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Portrait Mode's 3D data is available to any developer, so there's room for competing apps, in theory. But in the two years since this mode debuted in the iPhone 7, no other challenger has entered the arena, despite the fact that Apple sells through tens of millions of iPhones every quarter, and despite a culture where sharing selfies on social media has become as second-nature as driving a car.

Maybe we're just suckers for apps and photo tweaking, but we're hard-pressed to think of something else that costs 99 cents that will last for more than five minutes. The foam on your Starbucks latte probably cost more than that.

Takeaways

  • Apollo: Illumination, the iPhone app that uses dual lenses to add simulated lights to a photo after it's taken, is now on sale for 99 cents, and there are no in-app purchases or subscriptions.
  • You can add up to 20 light sources and tweak things like brightness, distance, and color.

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Tom McNamara is a Senior Editor for CNET's Download.com. He mainly covers Windows, mobile and desktop security, games, Google, streaming services, and social media. Tom was also an editor at Maximum PC and IGN, and his work has appeared on CNET, PC Gamer, MSN.com, and Salon.com. He's also unreasonably proud that he's kept the same phone for more than two years.