Calculating Global Overlap Windows in Sequential Row Readout Image Sensors
Calculate global overlap by subtracting array readout time from total exposure; fire external illumination within this window to emulate global shuttering.
Electronic Rolling Shutter
Scanning Mechanism
Sequential line by line data acquisition processes rows of an image at slightly different points in time. An electronic rolling shutter begins the exposure of one row while the previous row is being read out or integrated. This method allows for high resolution capture without the complex circuitry required for global shutter designs.
It remains the most common architecture for high pixel count sensors found in mobile devices and industrial cameras.
Temporal Offset
The delay between the start of the top row and the bottom row creates a time gradient across the image. When an electronic rolling shutter captures a fast moving object the geometric shape of the item appears slanted or skewed due to this progression.
Processing Sequence
Logic circuits manage the reset and readout pulses in a continuous wave that moves down the sensor. Each line in an electronic rolling shutter follows the same exposure duration but the window is shifted in time by a fixed horizontal period.
Motion Artifact
Distortions become more pronounced as the speed of the subject increases relative to the frame rate. Total scan time for an electronic rolling shutter determines the severity of the jello effect where vertical lines appear to lean during camera movement.