Apple Could Have Brought a Big iPhone X Feature To Older iPhone But Didn't, Developer Says (twitter.com)
Steven Troughton-Smith, a prominent iOS developer best known for combing new software codes for references for upcoming features, over the weekend indicated that portrait mode lighting effects, a major feature in the current iPhone generation -- iPhone 8 Plus, and iPhone X, could technically be added to iPhone 7 Plus from last year. The feature works like this: you take a picture, go to the photos app on your new iPhone and play with the "Lighting" effects. He writes: So yeah you just need to hexedit the metadata in the HEIC. Not quite sure where, I copied a whole section from an iPhone X Portrait Mode photo and it worked. Original photo taken on 7 Plus on iOS 11. Someone could automate this. Just to add insult to injury, if you AirDrop that photo back to the iPhone 7 Plus now it shows the Portrait Lighting UI, and lets you change mode. So Portrait Lighting is 100% an artificial software limitation. 7 Plus photos can have it, 7 Plus can do it.
Maybe they were in a hurry to get those features added for the new generation of smartphone and didn't want the time penalty of retro-porting and testing. No different from device driver support for old versions of Linux. Though eventually someone does get around to do retro-ports.
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From what I understand, portrait lighting depends on a depth camera. Once you take the photo, if you also have the depth information, you can indeed change the "portrait" settings on any iOS 11 device, but you can't take it since the iPhone 7 doesn't actually have the depth camera.Actually the 'developer' confuses portrait mode with portrait lighting.
Portrait mode which works on the iPhone 7 Plus, 8 Plus and X is accomplished by using the two cameras simulate the depth of field effect of a large diaphragm.
Portrait lighting uses the depth camera on the iPhone X to also get a depth map. It is used in turn to figure out which is the face/head and what is the background in the picture. It applies the light effects on the head and darkens the background. If you capture the picture on an iOS device that supports depth mapping, you can indeed edit it on another device since all the needed information is present in the photo.
Apple has a history of almost artificially restricting features like it did with FaceTime on non-front camera phones (iPhone 3GS). It made sense if you think about it, you can't see and be seen at the same time. At the time, jailbreaks allowed the activation of FaceTime on non-front camera devices, but it was almost pointless.
UNIX was not designed to stop you from doing stupid things, because that would also stop you from doing clever ones.