Working Principles of Global Shutter and Rolling Shutter

1. Global Shutter

The working principle of global shutter is illustrated in Figure 2. With global shutter, all sensor pixels start and end exposure simultaneously. Every pixel on the sensor receives light at the same moment with identical exposure duration. Upon completion of exposure, electric charges collected by each pixel are transferred to storage areas, and row‑by‑row data readout proceeds until the full image is captured.

This mechanism guarantees uniform exposure across the whole frame, eliminating image skew or distortion caused by fast‑moving subjects. The benefit of synchronous exposure is that fast‑moving objects such as aircraft propellers and high‑speed racing cars can be captured without motion blur or skewing. For instance, when shooting a high‑speed moving vehicle, the vehicle maintains its true shape without stretched or deformed wheels.

Advantages and Disadvantages of Global Shutter

Advantages: All pixels are exposed concurrently. High‑speed moving objects can be captured without image distortion or motion blur, making it ideal for moving‑object imaging.

Disadvantages: The minimum exposure time is constrained by physical limits, so further shortening of exposure duration is difficult.

2. Rolling Shutter

The rolling‑shutter mechanism is shown in Figure 1. Instead of exposing the whole frame at once, rolling shutter performs exposure row by row. When the first row starts exposure, remaining rows are still unexposed. The sensor exposes sequentially from top to bottom until all rows are finished.

Due to row‑sequential exposure, different pixels record light at different timestamps, which introduces distortion and motion blur for moving objects. This artifact, known as the rolling‑shutter effect, frequently appears when capturing high‑speed subjects. A typical example is a rotating aircraft propeller appearing bent or stretched in the captured frame.

Advantages and Disadvantages of Rolling Shutter

Advantages: Supports shorter exposure time; suitable for static‑scene shooting; delivers higher frame rates with lower manufacturing cost. Its hardware design is relatively simple since synchronous exposure control is not required.

Disadvantages: Row‑by‑row exposure causes motion blur and geometric distortion for fast‑moving objects, so it is not suited for high‑speed scenarios.

Rolling‑Shutter Effect and Motion Blur

Motion blur can be explained by the row‑sequential exposure principle. When relative motion exists between target object and camera system, pixels at different positions sample the object at different spatial positions during sequential exposure. By the time certain pixel rows are exposed, the object has already moved. The final image is a superposition of the object at multiple positions throughout movement, producing visible motion blur.

For example, shooting trees outside the window from a high‑speed train with a rolling‑shutter camera may result in tilted tree images. As each sensor row records the tree at a slightly offset position, visual skew occurs. Figure 1 clearly demonstrates how exposure delay affects image formation under row‑sequential readout.

Application‑Scenario Analysis

Global shutter exposes the entire scene synchronously and excels at capturing high‑speed motion. Typical use cases include sports events, traffic surveillance, and scientific research requiring precise capture of fast actions. In these applications, frame integrity must be preserved without blur or distortion, and global shutter delivers stable image quality.

Rolling‑shutter CMOS sensors are widely adopted for higher frame rates and lower power consumption. They fit general‑purpose and static‑scene applications such as landscape and still‑life photography. Where object movement is moderate, the rolling‑shutter effect exerts negligible impact on image quality.    

Mitigation of Motion Blur and Rolling‑Shutter Artifacts

Understanding the differences between global shutter and rolling shutter is critical especially for high‑speed object capture. For rolling‑shutter cameras, the following methods help suppress motion blur and rolling‑shutter distortion:

1. Shorten exposure time: Adjust shutter speed to reduce exposure duration and alleviate geometric distortion and blur of moving objects.
2. Increase lighting: In low‑light environments, widen aperture or deploy auxiliary lighting to keep images bright under short exposure settings.
3. Select proper shooting scenarios: If rolling‑shutter artifacts cannot be avoided, frame composition can exclude fast‑moving subjects; alternatively, the rolling‑shutter effect may be leveraged for special visual effects.