Rolling Shutter Motion Skew Calculator

Method, formula and assumptions

Displacement = horizontal image motion x full-frame readout seconds. Row interval = full-frame readout/(rows - 1). Ideal vertical-edge slope angle = atan(displacement/(rows - 1)).

Input definitions and supported units

• Measured full-frame row readout (ms): Measured or assumed numerical value, from 0 to 1000; zero is supported where the stated method permits it.
• Horizontal image motion (pixels/s): Measured or assumed numerical value, from -1000000 to 1000000; signed values are supported.
• Image height (rows): Whole-number count, from 2 to 100000; must be positive.
• Image width (pixels): Whole-number count, from 1 to 1000000; must be positive.

Worked example with answer

20 ms readout with 500 pixels/s horizontal motion creates 10 pixels top-to-bottom displacement. Across 2,000 rows, interval is 10.005 microseconds and slope angle 0.2866 degrees; displacement is 0.25% of 4,000-pixel width.

How to use the results

Negative motion produces opposite skew. Readout time is different from exposure time, so a fast shutter can leave this geometric distortion.

Results retain full precision internally and display up to four decimal places. Very small nonzero results use scientific notation rather than appearing as zero. Check the labels before comparing values across units.

Limitations and references

Assumes linear scan and constant translation; rotating motion, scan direction and cropping need different models. Readout must be measured for the actual camera mode.

The method is a self-contained arithmetic, geometric or explicitly stated mathematical model. There are no imported tariffs, empirical presets or equipment specifications; measured values and allowances must come from your own process.

Related planning tools

• Shutter Angle Exposure Calculator
• Flash Motion Freeze Pixel Budget Calculator

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