Line Capture Modes

Two line capture modes are available: Take-All-Lines and Tag-A-Line.

The following table summarizes the characteristics:

Characteristics Take-All-Lines Tag-A-Line
Camera line rate Variable, linked to web speed Fixed, defined by the frame grabber
Captured image data All lines All lines
Line tagging No Yes, linked to web speed
Image resampling Not required Required to be done by the application using tag metadata

Take-All-Lines Line Capture Mode

The camera line rate is proportional to the web speed to maintain a fixed pitch along the downweb web direction. Therefore, the Master Channel elaborates a Camera Trigger signal from the A/B signals using the Quadrature Decoder and, when necessary, the Rate Divider or the Rate Converter.

All lines are captured by the frame grabber when the acquisition is enabled. Threfore, the Master channel elaborates the Acquisition Enable signal from both edges of the position detector signal.

Tag-A-Line Line Capture Mode

The camera line rate is fixed. Therefore, the Master Channel elaborates a Camera Trigger signal using the Periodic Timer.

The downweb line rate is proportional to the web speed to obtain, after resampling by the application , a fixed pitch along the downweb web direction. The Master channel elaborates also a Tag Trigger signal from the A/B signals using the Quadrature Decoder and the Rate Divider. This signal will be used by all acquisition controllers to tag the lines of image data lines to be kept during the downweb resampling process.

The Master channel combines both Tag Trigger and Camera Trigger signals for transmission on the SyncBus.

All lines are tagged and captured by the frame grabber when the acquisition is enabled. Therefore, the Master channel elaborates the Acquisition Enable signal from both edges of the position detector signal in the same way as for the Take-All-Lines mode.

The RGB components data of the first pixel of each image line are replaced by a tag indicating if the line was preceded by a Tag Trigger or not.

  • All data bits of R,G and B components are set to 1 when a Tag Trigger occurred during the preceding line interval.
  • All data bits of R,G and B components are set to 0 when no Tag Trigger occurred during the preceding line interval.
Note: When ColorFormat is set to RGB32, the alpha component is not tagged!
All image data lines are delivered to the application. The application has to perform downweb resampling using tags to obtain an undistorted image with a constant downweb line pitch.