Rolling Shutter Distortion Lab

Sensor & Motion

Row readout time 20 µs

Sensor rows 120

Scene pan speed 0.80 w/s

Shutter Type

Live Readouts

Frame readout T

2400 µs

Shutter mode

Rolling

Skew shift Δx

0 px

Skew angle θ

0.0°

Scan progress

row 0 / 120

How it works

A CMOS sensor (every phone camera) does not expose the whole frame at once. It resets and reads pixel rows one after another, so row r is actually sampled at a slightly later instant than row 0:

t(r) = t0 + r·τ          (rolling shutter)
t(r) = t0  for all r      (global shutter / CCD)
T = N_rows · τ            (total frame readout time)

If the scene (or the phone) moves sideways at velocity v while the sensor scans, each row captures the object at a different position. The top-to-bottom position shift is:

Δx = v · T
θ  = atan( Δx_px / H_px )   (apparent skew angle of a vertical edge)

A truly vertical bar therefore renders as a slanted line — the classic "leaning skyscraper" or bent-propeller-blade rolling-shutter artifact. A global-shutter sensor exposes every row at the same instant t0, so Δx = 0 and vertical lines stay vertical no matter how fast the scene moves.

Row readout time τ — real phone sensors run 5–30 µs/row; slower readout (bigger τ) means more skew for the same motion.
Sensor rows — more rows means a longer total readout time T = N·τ for one frame.
Pan speed — how fast the striped scene sweeps across the frame, in frame-widths per second.
Playback here runs 1000× slower than the real sensor (1 µs of sensor time shown as 1 ms on screen) purely so the row-by-row scan is visible — the formulas above use the real µs values.

Captured photoROLLING

Scanned rows (bars) Current scan line

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