The Difference Between "Grab" and "Acquisition" in Camera Control

The difference between "Grab" and "Acquisition" in camera control

When controlling a camera from software, the terms "Grab" and "Acquisition" come up often. They sound similar, but each has a different meaning and role. Understanding the difference is especially important when using camera software such as Basler Pylon Viewer.

Grab

"Grab" refers to the operation of "acquiring" or "capturing" image data from the camera. Clicking the "Grab" button in Pylon Viewer is this operation.

• Main meaning and role:
  • Acquiring a single frame: In its most basic sense, it means bringing a single image frame from the camera into the PC's memory. Pressing the "Grab" button in Pylon Viewer normally acquires one image according to the trigger settings.
  • Starting live view: In many camera viewer applications, starting "Grab" makes the camera begin transferring images to the PC continuously, and they are shown on screen in real time. This is also called "live view" or "preview" mode.
  • Focus on data transfer: "Grab" focuses on the process of transferring the digital data captured by the camera to the PC and making it available for use.
  • Relation to software triggers: When a software trigger is configured, the "Software Trigger" button in Pylon Viewer effectively sends one trigger to the camera through a "Grab" operation and has it acquire one image.

Acquisition

"Acquisition" is a broader concept that refers to the camera's entire "image acquisition process". It goes beyond acquiring a single image: it manages the internal state and settings that let the camera keep generating images, as well as starting and stopping that process.

• Main meaning and role:
  • Starting and stopping image generation: AcquisitionStart starts the camera's image generation engine, and AcquisitionStop stops it. This makes the camera ready to generate images continuously according to the configured frame rate and trigger mode.
  • A continuous process: "Acquisition" usually means the state in which the camera continuously generates and transfers images. This includes continuous capture driven by an internal timer and frame generation in response to external triggers.
  • Managing the camera's internal state: "Acquisition" is largely about managing the state of the camera as a whole, that is, whether it "is currently capturing images or is ready to capture images."
  • Relation to trigger modes:
  • Trigger Selector = Acquisition Start is used when this "entire image acquisition process" is started by an external trigger signal. Once this trigger is issued, the camera starts generating images continuously.
  • Trigger Selector = Frame Start is used when the exposure timing of each frame is controlled by a trigger signal, on the premise that "Acquisition" has already started (the camera is in a state where it can generate images).

Main differences between "Grab" and "Acquisition"

Summary

• "Acquisition" is the higher-level concept of starting and stopping the camera's "image-capturing state." Think of it as switching the camera's image generation engine on and off.
• "Grab" is the concrete operation of actually capturing image data from a camera whose "Acquisition" has started. When images keep streaming in live view, continuous Grabs are happening behind the scenes.

If you normally use Frame Start, you are controlling the timing of individual frames with an external trigger, on the premise that the camera's Acquisition has already started (or starts automatically). Acquisition Start, on the other hand, is best understood as the more fundamental command: "Camera, start capturing!"