iPhone Depth Effect: How It Works and Why Photos Fail

What the depth effect is

The depth effect is the lock-screen look where the subject of a wallpaper photo rises in front of the clock, so the digits seem to sit inside the scene. When you set a photo, the phone runs a subject-segmentation model over it (the same kind of model that lets you lift a subject out of a picture) and produces a mask that marks which pixels are the subject and which are background. If the phone trusts the mask and the composition allows it, it draws the clock between the two layers: one photo, split in two by a model, with the time slotted in between.

Some dated facts, checked 2026-08-09. The effect arrived with the redesigned lock screen in iOS 16 (2022) and behaves the same way through iOS 26. It requires an iPhone with the A12 chip or newer: iPhone XS and XR onward, including the second- and third-generation iPhone SE. iPhone X and iPhone 8 run iOS 16 but never show the effect, because the segmentation model does not run on those chips. It works on ordinary photos and needs no portrait mode or depth map. The model reads flat pixels, which is why a screenshot of a sticker can layer while a real portrait shot sometimes refuses.

Two composition rules decide when it engages. Both are the system's own behavior, and no photo can override them. First, the subject may overlap the clock only a little. Cover too much and the effect switches itself off; the commonly observed threshold is roughly the lower half of the clock. Second, the effect never runs while widgets are on the lock screen. Widgets occupy the band the subject would layer into, so adding one turns the layering off, and you have to choose between widgets and depth.

The decision you cannot watch

Your phone's own subject segmentation decides whether the effect switches on, at the moment you set the wallpaper. No site can run that model, and it gives no score and no reason: you either get the layered look or you don't. From outside the phone you can measure three things: whether the image has enough pixels for your panel, whether the subject sits in the band where layering happens, and whether the clock area is legible. Those are the three failures you can fix, and they are what the checker measures. The final call happens on the phone.

The phone does give you one live signal, and it is the fastest test there is: in the wallpaper editor, the effect turns on and off as you pinch and reposition. That flicker is the model deciding again with each new crop. If any position makes the layering appear, the photo segments, and your problem is placement, which you can fix. If no position produces it, the model is not finding a subject it trusts, and the sections below help you decide whether to keep trying.

Why photos fail

Subject in the wrong place. The workable zone is narrow. Too low, and the subject never reaches the digits: the effect may technically be on, but nothing overlaps, so the lock screen looks flat. Too high, and the subject would swallow the clock, so the system turns the layering off entirely. The subject's top edge needs to rise over the lower portion of the digits and stop there. This is the most common failure, because phone photos put subjects mid-frame and the clock sits near the top.

Widgets. Any widget turns the effect off automatically, with no warning: the layering just doesn't appear. If you added widgets months ago and forgot, every photo you try will "fail" until they come off.

The toggle itself. Depth Effect is an option in the wallpaper editor's three-dot menu, and it can simply be off. If the option is unavailable, the model is telling you, in the only way it can, that it found no subject in this photo, and no setting will change that.

Resolution. An image smaller than your panel's native pixels gets upscaled, and upscaling softens edges, including the subject's outline, which is exactly what segmentation depends on. A soft photo can lose the effect that a sharp export of the same scene gets. The size chart has every model's native pixels, and the checker gives a pass or fail against the one you pick.

Busy backgrounds and unclear subjects. The model wants one subject with a clean outline against a background it can tell apart. Crowds, foliage, reflections, a dark coat against a dark doorway and hair against a similar tone all give it a boundary it cannot commit to, and then it declines.

Also reported. Troubleshooting threads repeatedly name Low Power Mode and the Reduce Motion accessibility setting as suppressing the effect for some users. Neither has been measured here, but both take seconds to rule out.

The fix checklist

Written against iOS 26, checked 2026-08-09. The names are factual references to the system's own controls, and menus move between versions. Work from the top down, because the early items are the cheap ones.

1. Take the widgets off the lock screen, or accept a flat wallpaper.
2. Pinch and reposition in the editor until the subject's top edge rises over the lower part of the digits. Watch the effect flicker on and off as you move; the flicker shows whether any workable position exists.
3. Check the three-dot menu and confirm Depth Effect is switched on. If it is unavailable, stop adjusting settings. The model found no subject, so the fix is a different photo.
4. Measure what you can. Run the photo through the checker for an exact resolution verdict for your model, a band overlay showing where the subject's top edge should land, and the contrast ratio behind the clock.
5. Feed it native pixels. Use the original export. Messaging apps recompress and downscale images, so a copy saved from a chat thread has a softer outline, and a soft outline is the worst input for segmentation.
6. Choose a cleaner frame of the same subject if the model keeps declining: one subject, a hard outline and a background that differs in tone. Moving two steps to the left is often enough to get a photo that segments.
7. Rule out the reported modes: turn off Low Power Mode and Reduce Motion, then set the wallpaper again.

When to give up

Some photos never segment, and recognizing them saves an evening. A landscape with no single subject gives the model nothing to lift. A subject that fills the frame edge to edge leaves nothing to layer in front of, because the mask would be the whole photo. Fuzzy or translucent boundaries (hair against a matching tone, steam, glass, motion blur) deny the model the clear outline it needs. Low tonal separation between subject and background fails for the same reason it would fool your own eye at a glance. Cropping and brightness edits rarely rescue these photos, because the problem is the boundary itself.

You still have two good options. Use the photo flat: a clock on top of a well-chosen image looks intentional, and the checker's contrast number matters even more then, because legibility does all the work. Or switch to a made wallpaper. It is composed around the clock from the start, nothing in it needs to segment, and the calm region behind the digits is part of its design.