A Wallpaper for a Tablet That Turns
A phone stays upright and a monitor stays wide, but a tablet changes its mind several times an hour, and the picture behind the icons has to survive every turn.
A tablet is the only screen in the house without a fixed orientation. Read in bed and it stands tall; prop it against a keyboard and it lies wide. To avoid a black band every time it rotates, most systems scale the wallpaper until it covers the long edge in both positions, which in practice means treating the image as a square. On a 4:3 tablet about a quarter of the picture is out of view at any moment, and which quarter depends on how you are holding it.
That is why the subject wants to sit near the centre. The area both orientations can see is a square as wide as the short edge, and anything outside it appears in one position and vanishes in the other. A lighthouse on the far left of a wide frame looks well placed at the desk and gets cut off in bed. Broad, even scenes travel better: a sea horizon, a valley of mist, a canopy seen from above, where losing a strip on either side changes nothing that matters.
Resolution follows from the square as well. If the long edge of the screen is 2732 pixels, the image needs roughly 2732 on its short side too, or the system enlarges it and the detail goes soft. A 3840 by 2160 landscape photo just about covers a mid-size tablet; for the largest models a taller original is the honest answer. The test takes ten seconds: set it, then turn the tablet slowly both ways and watch what slides out of the frame.
