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MultiCam Boards Documentation > MultiCam Documentation > MultiCam User Guide > The Channel Class > Understanding Grabber Specification > How to Define the Grabbing Window? > The MAN Method

The MAN Method

Upon setting the parameter to the MAN value, the grabbing window firstly remains in the size and position previously defined, usually the default condition installed by NOBLACK. This method allows the user to subsequently freely adjust the grabbing window.

The size is adjusted with WindowX_Px and WindowY_Ln and the position with OffsetX_Px and OffsetY_Ln.

The offset parameters measure the displacement of the center of the grabbing window respective to the center of the camera active window.

The grabber's sampling frequency, which can differ from the camera's pixel clock frequency when analog or master synchronization is used, remains unchanged when GrabWindow is set to MAN. This means that the pixel aspect ratio remains unchanged when varying the size of the grabbing window.

On a reduced window, the user can adjust OffsetX_Px or OffsetY_Ln provided that the grabbing window remains inside the maximal active window. For other values, an internal protection limits their effect.

As an example, on the above picture, the camera delivers an image composed of 1010 pixels and 640 lines as defined using Hactive_Px and Vactive_Ln. After setting GrabWindow to MAN, a smaller window of WindowX_Px=640 pixels and WindowY_Ln=480 lines is selected.

When both OffsetX_Px and OffsetY_Ln are zero, the centered image is transferred to the surface. As illustrated, the image is locked on the center of the camera active window.

To obtain another grabbing window, if setting OffsetX_Px to 100 and OffsetY_Ln to 60, the below image will then be transferred to the surface.

Any value of OffsetX_Px and OffsetY_Ln are accepted but an internal protection will always maintain the grabbing window inside the camera active window.

If trying OffsetX_Px=100 and OffsetY_Ln=200, the internal protection limits the offset on Y. The below image will be transferred to the surface.