Irish developer Steven Troughton-Smith has discovered that old Portrait Mode photos currently cannot be enhanced using Apple’s new Portrait Lighting effects without resorting to trickery.
Is this yet another artificial software limitation from Apple?
To test his theory, Troughton-Smith began by transferring to his Mac a Portrait Mode photo taken with his iPhone 7 Plus. He then made some quick metadata changes to the file before sending it to his iPhone X. Much to his surprise, the regular Portrait Lighting interface for the tweaked Portrait Mode image magically appeared in the stock Photos app.
In other words, it’s just some metadata preventing you from applying those cool Portrait Lighting effects to your old Portrait Mode photos.
…what I would expect, however, is the Portrait Lighting editing UI to show up (on the 8/X) on older Portrait Mode photos taken with a 7 Plus, so they can take advantage of better machine learning & evolved software — especially if it's just a metadata change blocking it
— Steve Troughton-Smith (@stroughtonsmith) November 20, 2017
You can test this yourself on any depth-of-filed image, old or new, as long as it was taken it with your iPhone 7 Plus using the old Portrait shooting mode.
Fire up the Photos app, select one of your Portrait Mode images and hit Edit. If this is a depth-of-field image, you’ll see the yellow label “Portrait” shown at the top. What you won’t see upon tapping the Edit button is the Portrait Lighting interface, not even on iPhone X.
As a result, you’re stuck with your Portrait Mode photos without the ability to enhance them using the new Portrait Lighting effects. This is especially weird knowing that both Portrait Mode and Portrait Lighting images use the same depth map.
iPhone X supports depth-of-field photography on both front and rear cameras. On iPhone 8 Plus and iPhone 7 Plus, Portrait Mode photos can only be taken using the rear dual-lens camera because only iPhone X has a front camera capable of sensing depth.
But what could be the reason for this artificial software limitation?
My iPhone X heats up if I take too many Portrait Lighting photos in a row. I can’t image how bad that’d be on the 7’s.
— Mike 💉 (@mikbre) November 19, 2017
Daring Fireball’s John Gruber says Portrait Lighting is limited to iPhone X and iPhone 8 Plus for performance reasons, as these phones run the latest A11 Bionic chip with Apple’s much-improved image signal processor and a neural language dedicated to machine learning.
According to Gruber:
My understanding is that these effects aren’t enabled on iPhone 7 Plus because performance was really slow at capture time. It really does require the A11 Bionic chip for adequate performance live in the camera. And Apple decided against shipping it as a feature for iPhone 7 Plus that could only be applied in post, because that felt like half a feature. So I’ve heard.
The theory is that previewing Portrait Lighting effects before the capture process would tax the CPU/GPU beyond what the A10 Fusion chip in iPhone 7 Plus can handle. I get the importance of live camera preview, but there’s no reason why iOS shouldn’t upgrade all Portrait Mode photos in our library so we could enhance them with Portrait Lighting effects.
Apple previously limited certain iPhone features to the latest hardware.
With Animoji, for instance, the new TrueDepth camera is needed to capture your facial movement even though the Animoji feature could have as well been implemented via the regular front-facing camera.
Should Apple bring Portrait Lighting effects to older iPhones?
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