iPhone Duo wallpapers

• Unfolded, 2670 × 1878. The Foldable Open 10:7 file at 2670 × 1878 fills it exactly, nothing cropped.
• Cover, 1398 × 2034. The Foldable Cover 16:11 file at 1398 × 2034 fills it exactly, nothing cropped.

Opening a book-style fold makes the screen wider, not taller. That is the thing most size guides get backwards, this one included until somebody looked at it: Apple quotes the inner display as 1878 by 2670, an iPhone resolution is quoted height first, and on a fold that convention stops being safe. The unfolded panel is 2670 across and 1878 tall. The check that settles it is physical rather than typographic: shut, the phone is half its open self, and half the open panel is the cover to within two per cent. On the other reading it misses by nearly a third.

Do not use the phone file. It is the obvious pick and the wrong one twice: wrong shape and wrong way up. The unfolded screen is 2670 pixels across and the 19.5:9 phone wallpaper is 1320 wide and 2868 tall, so it has to be stretched 2.02 times to cover that panel. Upscaling is the one thing these packs exist to avoid: every file is rendered straight to its native size in code, and blowing one up throws that away and puts the banding back into the gradient.

Apple describes the two screens as sharing an aspect ratio, and they nearly do, in perpendicular directions: open works out at 1.4217 to 1 landscape and the cover at 1.4549 to 1 portrait, 2.3 per cent apart. That is the same shape turned ninety degrees, which is exactly what a hinge down the middle does to a rectangle.

Scale to fill and crop the overflow, which is what the phone does with a wallpaper. Anything stretched is the file being blown up past the size it was drawn at.

A tablet gets one square file here, because a tablet is one screen that rotates and a square is correct in both orientations. A folding phone is not that: it is two different panels at two different pixel densities, and Apple ships its own Duo wallpapers as two files for the same reason. So each is composed at its own size rather than cropped from the other. The cover gets the same treatment as the phone files, with the fan drawn in so the top third stays quiet under the clock and the status bar; the unfolded panel is a landscape composition like the desktop and the tablet, where the beams run the full width. Both are in Prism, Sundrift and Gradient, and both went to everyone who had already bought one at no extra cost, which is what future sizes included means.