Camera Windowing
CMOS technology allows sensors to read out only selected groups of pixels. This can be used to restrict the acquisition to windows of interest (WOI) rather than full images. This windowing increases the readout speed and hence, the maximum achievable frame rate.
Most cameras featuring windowing are capable of extracting only one (rectangular) window from the sensor. This feature is supported natively by Grablink boards and MultiCam. In such a case, the window of interest is simply treated as a frame. Moreover, the High Frame Rate (HFR) acquisition mode can be used to accommodate extremely high acquisition rates (1000 fps or more).
Some cameras allow the definition of multiple rectangular WOI with possible overlapping. MultiCam implements a solution that meets the request to support the multiple WOI feature of these cameras. In addition, some of these cameras can store the definition of several sets or banks of WOI, and quickly switch between them.
Usage
The camera windowing with multiple WOI is supported on Grablink Expert 2. MultiCam exposes parameters describing the position and size of the WOI that must be set up in the camera.
Please note that setting up the WOI in the camera is the responsibility of the user application. This involves sending a message to the camera through the serial line, according to the camera specification. However, once the WOI have been configured in MultiCam, the user application can retrieve the packet of bytes to send to the camera through a dedicated parameter.
Several MultiCam channels can be created and configured independently, each channel corresponding to one WOI bank. Switching from one bank of WOI to another is accomplished by the user application sending commands to the camera through the serial line and activating the corresponding channel.
The data of each WOI is transferred to its corresponding location in the image in the memory.
The camera windowing mode is activated and deactivated through a MultiCam parameter. In addition, a dedicated collection of integer parameters defines the multiple WOI.
MultiCam Parameters
For detailed information refer to Camera Advanced Features Category.
- The WoiOrgX, WoiOrgY, WoiHeight and WoiWidth parameters describe the WOI positions and sizes.
- The GrabWindow parameter activates the camera windowing mode through the WOI value.
- The CameraWoiBankSetupCmd and CameraWoiBankSelectCmd parameters contain the message needed to configure the WOI in the camera and to activate one of the WOI banks.