Editing Openai/693e48dd-ce3c-800a-b636-9b3efde0fdec (section)

==== When you walk forward while holding the phone: ====
* Your wrists naturally tilt the phone very slightly downward
* When you walk backward, they tilt very slightly upward

You don’t feel this tilt, but the phone’s orientation sensors and display pipeline absolutely do.

Now combine that with how modern phone displays work:

===== They use: =====
* tiled rendering
* local tone-mapping regions
* temporal dithering
* per-frame contrast compensation

These regions are recomputed when orientation changes, even by fractions of a degree.

So what you’re seeing is:

: 

That produces:
* motion opposite your body direction
* then a brief settle as the pipeline stabilizes

That “down then back / up then back” pattern is exactly what reprojection artifacts do.