CMOS cameras offer two primary exposure and readout modes: rolling shutter and global shutter. Each mode has distinct advantages and disadvantages that make one or the other more suitable depending on your specific application requirements.

Rolling Shutter Mode

In this mode, exposure occurs row by row starting from the center of the sensor array. The readout progresses outward in both directions horizontally. With a maximum readout rate of 560 MHz, adjacent rows experience a 10 ms time difference during exposure. This sequential nature can cause spatial distortion in rapidly moving scenes because different portions of the image are captured at slightly different times.

While rolling shutter offers benefits like low readout noise (typically 1.2 e) and fast frame rates (up to 100 fps), it presents challenges for motion capture applications where precise temporal correlation is critical. The mode also complicates synchronization with external triggers due to its complex operation.

Global Shutter Mode

Unlike rolling shutter, global shutter captures all pixels simultaneously during exposure. This eliminates spatial distortion entirely and simplifies synchronization processes. However, this approach comes with tradeoffs: higher readout noise (typically 2.5 e) and the need for background subtraction to reset pixel charges, which effectively halves maximum frame rates compared to unsynchronized rolling shutter operation.

Choosing Between Modes

The optimal mode selection depends on several factors:

  • Speed requirements of your application
  • Size and complexity of objects being imaged
  • Importance of temporal correlation accuracy
  • Signal-to-noise ratio considerations
  • Frame rate demands

For moving object tracking or high-speed applications, global shutter’s elimination of motion artifacts makes it preferable despite its limitations. Conversely, static scene imaging with frame rate constraints often benefits from rolling shutter’s performance characteristics.

Understanding these fundamental differences enables engineers to select the most appropriate camera mode for their specific vision system requirements.

Last Updated: 2025-09-04 19:23:29