Camera Shutter Technology: Rolling vs Global Sensors
- ridgerun
- 21 hours ago
- 5 min read
When developing an embedded vision system, choosing the right image sensor goes far beyond resolution or form factor. One of the most influential—yet often overlooked—characteristics is the camera shutter technology. Whether you’re building a real-time robotics platform, a synchronized multi-camera array, or simply capturing fast motion scenes, the shutter mechanism directly impacts image fidelity, timing accuracy, and motion artifact resilience.
In this article, we’ll explore the core differences between the two main types of camera shutter technology, why they matter in embedded applications, and how RidgeRun supports both through driver-level synchronization and camera integration on Linux platforms.
Table of Contents
The Two Types of Camera Shutter Technology
Aside from the physical interface, the image sensor’s shutter type is a crucial factor in embedded vision. This refers to how the sensor captures each frame. There are two main types:
Rolling Shutter
The exposure of pixels in this camera shutter technology is staggered row by row (not all pixels integrate light simultaneously). The sensor reads out line-by-line, e.g., starting at the top of the frame and ending at the bottom. Rolling shutter sensors are very common (especially CMOS sensors in smartphones and low-cost cameras) because they are easier to design and can achieve higher resolutions at a lower cost. However, when capturing fast motion, rolling shutters can cause geometric distortions known as rolling shutter artifacts.
Global Shutter
With this camera shutter technology, the exposure starts and ends for all pixels at the same time. After the exposure period, the whole frame is read out (which still happens sequentially in time, but the exposure is simultaneous). Global shutter eliminates the skew and distortion for moving objects, since the entire scene is effectively frozen in time during capture. Global shutter sensors are preferred for high-speed motion capture (e.g., machine vision, robotics), but are typically more expensive and sometimes lower resolution than equivalent rolling shutter sensors.
Explaining Rolling Shutter Artifacts
If an object moves quickly while the frame is scanned, it appears distorted. A classic example is a fast-spinning propeller or fan – a rolling shutter can make the propeller blades look curved or fragmented because different parts of the blade were at different positions during the sensor readout. The photo below (taken from an airplane’s propeller with a CMOS rolling shutter camera) shows this effect – the propeller blades appear bent due to the rapid motion and line-by-line capture:
The propeller’s blades look warped because the top of the image was captured at a slightly different time than the bottom. A global shutter camera would capture the blades in a true circular shape (but might still show motion blur if the exposure time isn’t short enough).
For scenes with fast motion or when the camera itself is moving rapidly, rolling shutter artifacts can be problematic. These include use cases like drone cameras (fast maneuvers causing background skew), robotics (capture of quick motions), or any application needing precise image measurements (where distortions would throw off computer vision algorithms). Rolling shutter can also cause partial exposure of fast flashes (like a strobe light might only appear in part of the image). There are some techniques to mitigate rolling shutter issues:
Increase the frame rate or use a very short exposure time (reducing the time difference between the top and bottom of the frame). This can reduce, but not entirely eliminate, the distortion.
Use algorithms to correct distortion if the motion is known (though this is complex and not always effective).
Some sensors offer a compromise called “Global Reset” or “Global Reset Release” where the exposure is global but readout is rolling – aiming to reduce distortion while using a rolling shutter readout.
Global Shutter Advantages
Global shutter sensors avoid these artifacts entirely. They are essential for applications like:
Machine vision / industrial inspection: where objects on a conveyor are moving and need accurate measurement.
Robotics and SLAM (Simultaneous Localization and Mapping): fast-moving robots or scenes to be mapped benefit from undistorted images for accurate feature detection.
High-speed video capture: e.g., tracking a baseball or a speeding vehicle, the global shutter ensures the object’s shape is correctly captured in each frame.
Multi-camera synchronization: If using multiple rolling shutter cameras, even if triggered at the same time, slight readout differences could cause each camera to capture a moving object at a slightly different pose. Global shutter ensures truly simultaneous capture across all sensors.
Global Shutter Trade-offs
Cost and complexity are the main downsides of this camera shutter technology. Global shutter CMOS sensors require on-pixel storage (or more complex circuitry) to hold the charge while reading out, which increases silicon area and often reduces full-well capacity (affecting dynamic range). They also historically had lower resolution options compared to rolling types, though this is improving (e.g., Sony Pregius line, OnSemi AR0234, etc., are global shutter HD sensors). Power consumption might be a bit higher, too. Thus, if your application doesn’t involve fast motion, a rolling shutter camera can achieve the same results at lower cost – for example, a static security camera or a video conferencing camera can use rolling shutter without issues since the scene is mostly static.
When to Choose Which Camera Shutter Technology
Use rolling shutter when cost is critical and your scene or object motion is minimal or slow. Many surveillance and automotive cameras actually still use rolling shutter but mitigate issues via high frame rates and algorithmic compensation if needed. Rolling shutter cameras are usually smaller and have more megapixels (for a given price point) than global shutter ones.
Use global shutter for any high-speed imaging, precise measurement, or when combining multiple cameras in a stereo or panoramic setup where alignment matters. For instance, a robot arm picking fast-moving objects would benefit from a global shutter to avoid image skew. In automotive, certain applications like reading license plates or detecting flickering LED taillights under varying frequency lighting prefer global shutter.
For embedded developers, it’s important to note that the camera driver typically doesn’t need to handle rolling vs global differently – it’s more about the hardware choice. However, enabling features like synchronization (triggering sensors simultaneously) ties into this: a global shutter sensor often provides an input trigger or uses a common clock for sync, whereas rolling shutter sensors might require careful timing on the frame start if precise sync is needed.
Rely on RidgeRun
Camera shutter technology is second nature to RidgeRun. We've worked on multi-camera synchronization at the driver level, including programming external triggers and using common I²C commands to trigger multiple sensors together.
For more technical depth or assistance, consult RidgeRun’s Developer Wiki or reach out to our team—we’re here to help turn cutting-edge camera technology into reality on embedded Linux platforms.