grab_region

Herror ::grab_region_async ( Hobject *Region, const HTuple &FGHandle, const HTuple &MaxDelay ) HRegion HRegion::GrabRegionAsync ( const HTuple &FGHandle, const HTuple &MaxDelay ) HRegionArray HRegionArray::GrabRegionAsync ( const HTuple &FGHandle, const HTuple &MaxDelay )

Grab and segment an image from the specified frame grabber and start the asynchronous grab of the next image.

The operator ::grab_region_async grabs an image via the frame grabber specified by FGHandle, segments it, and starts the asynchronous grab of the next image. The desired operational mode of the frame grabber as well as a suitable image area can be adjusted via the operator ::open_framegrabber. Additional (frame grabber specific) settings might be possible via ::set_framegrabber_param. The grab of the next image is finished via ::grab_region or again via ::grab_region_async. If more than MaxDelay ms have passed since the asynchronous grab was started, a new image is grabbed (the asynchronously grabbed image is considered as too old). If a negative value is assigned to MaxDelay this control mechanism is deactivated.

Parameters

`Region` (output_object)	region(-array) `->` Hobject : HRegion(Array)*
Grabbed and segmented image: Region(s).

`FGHandle` (input_control)	framegrabber `->` HTuple.long
Handle of the frame grabber to be used.

`MaxDelay` (input_control)	number `->` HTuple.double
Maximum tolerated delay beteween the start of the asynchronous grab and the delivery of the image [ms].
Default value: -1.0
Suggested values: -1.0, 20.0, 33.3, 40.0, 66.6, 80.0, 99.9

Example

/* Select a suitable frame grabber FgName */
info_framegrabber(FgName,"ports",&Information,&Val) ;
/* Choose the port P and the input line L your camera is connected to */
open_framegrabber(FgName,1,1,0,0,0,0,"default",-1,"default",-1.0,
                  "default","default","default",P,L,&FgHandle) ;
/*  grab image, segment it, and start next grab */
grab_region_async(Region,FgHandle,-1.0) ;
/*  Process Region ...                                                */
/*  Finish asynchronous grab, segment this image, and start next grab */
grab_region_async(Region,FgHandle,-1.0) ;
close_framegrabber(FgHandle) ;

Result

If the frame grabber is open the operator ::grab_region_async returns the value H_MSG_TRUE. Otherwise an exception handling is raised.

Possible Predecessors

::open_framegrabber, ::grab_image_start

Possible Successors

::grab_region, ::grab_region_async, ::grab_image_start, ::grab_image, ::grab_image_async, ::close_framegrabber

Module

Image / region / XLD management