MVTec HALCON 6.0: Virtual Frame Grabber Interface

HALCON 6.0 Virtual Frame Grabber Interface

This page provides the documentation of the HALCON virtual frame grabber interface which allows reading images from file(s) by using the regular operators of the HALCON frame grabber interface. Registered customers can download the latest revision of this interface from the MVTec WWW server.

Revision: 2.6

Introduction

The HALCON virtual frame grabber interface allows you to load images and image sequences from files by using the regular frame grabber operators open_framegrabber(), grab_image(), grab_image_async(), and close_framegrabber(). Thus, you are able to test and debug your frame grabber application without having installed a real frame grabber board in your computer. All you have to do is to choose "File" in the parameter Name of open_framegrabber() and to give the proper file name of the image(s) to be loaded in the parameter CameraType. The CameraType parameter can be either the file name of a

Single image: In this case every subsequent call of the operator grab_image() or grab_image_async() will load this image file. Note that the image name can either be given absolutely (e.g., "C:\\MyImages\\MyPicture") or relatively to your environment setting %HALCONIMAGES% (e.g., "MyPicture"). Furthermore, you can also choose to specify the full image name (e.g., "MyPicture.tif") or you can omit the file extension (e.g., "MyPicture"). In the latter case HALCON automatically appends the usual file extensions of the supported image formats (tiff, tif, jpg, jpeg, pbm, pnm, pgm, ppm, gif, bmp, pcx, ras, ima, xwd).

Sequence file: A sequence file is a file which contains in each line the name of a single image file. In this case the first call of the operator grab_image() or grab_image_async(), respectively, will load the first image file, the second call will load the second one etc. In case of a failure loading an image an error will be returned and the next call will load the succeeding file. After the last entry in the sequence file has been reached grab_image() will start from the first image file again (looping). Both the name of the sequence file as the image file names within the sequence file can either be given absolutely (e.g., "C:\\MyImages\\MySequence") or relatively to your environment setting %HALCONIMAGES%. Usually, the sequence file has the extension ".seq" (you can also omit to specify this file extension).

AVI file: Running a Windows operating system the virtual frame grabber interface also provides reading video streams in AVI file format. In this case the first call of the operator grab_image() or grab_image_async(), respectively, will load the first image file, the second call will load the second one etc. After the last frame of the AVI file has been reached grab_image() will start with the first frame again (looping). The name of the AVI file can either be given absolutely (e.g., "C:\\MyImages\\MyAVIFile") or relatively to your environment setting %HALCONIMAGES%. The AVI file has the extension ".avi" (you can also omit to specify this file extension).

An example for using the HALCON virtual frame grabber interface can be found in the examples/hdevelop/Image/Framegrabber and in the examples/hdevelop/Applications/FA directory, e.g., "pattern.dev". An example for a sequence file can be found in %HALCONROOT%\images\pendulum\.

System Requirements

HALCON virtual frame grabber interface HFGFile.dll for Windows systems (or parHFGFile.dll for use with Parallel HALCON) or HFGFile.so for most UNIX systems, respectively. Depending on your system architecture, this file should reside either in bin\%ARCHITECTURE% (Windows) or in lib/$ARCHITECTURE (UNIX systems) within the HALCON base directory %HALCONROOT% you have chosen during the installation of HALCON.

Description

Parameters for open_framegrabber():

Name 'File' The name of the HALCON frame grabber interface.

HorizontalResolution --- Ignored.

VerticalResolution --- Ignored.

ImageWidth --- Ignored.

ImageHeight --- Ignored.

StartRow --- Ignored.

StartColumn --- Ignored.

Field --- Ignored.

BitsPerChannel --- Ignored.

ColorSpace --- Ignored.

Gain --- Ignored.

ExternalTrigger --- Ignored.

CameraType 'filename' The camera type parameter is used to specify the file name of either a single image file, an AVI file, or a sequence file containing the file names of a whole image sequence (see introduction above). Default: 'fabrik'.

Device --- Ignored.

Port --- Ignored.

LineIn --- Ignored.

Parameters for set_framegrabber_param():

'frame_number' number AVI format only. The parameter sets the number of the next frame to be grabbed by grab_image() (grab_image_async() respectively).

Parameters for get_framegrabber_param():

Additional parameters supported by get_framegrabber_param() only. Note that all parameters supported by set_framegrabber_param() can also be accessed by get_framegrabber_param().

'revision' revision Revision of the HALCON virtual frame grabber interface File.

'start_frame' number AVI format only. The parameter returns the number of the first frame of the AVI video stream.

'end_frame' number AVI format only. The parameter returns the number of the last frame of the AVI video stream.

Release Notes

Revision 2.6 (Jun 5, 2003):

Bugfix in accessing the same file simultaneously.

Revision 2.5 (Dec 9, 2002):

Improved timing behavior when reading from sequence files.
Improvement of AVI file error treatment (Windows only).

Revision 2.4 (Apr 25, 2002):

Bugfix in correct handling of sequence files and file extensions.

Revision 2.3 (Jun 22, 2001):

New: grabbing of '.ima' file types.
Grab calls step over load failures of images in sequence files.

Revision 2.2 (Dec 15, 2000):

Bugfix in reading avi files with 24 bpp (Windows only).

Revision 2.1 (Oct 26, 2000):

Support of AVI file format (Windows only).
Parameter 'frame_number' expands parameter list of set_framegrabber_param().
Parameters 'frame_number', 'first_frame', 'last_frame' expand the parameter list of get_framegrabber_param().

Revision 2.0 (Jul 4, 2000):

Adaptation to the HALCON 6.0 frame grabber interface.
Renaming from 'VirtualFG' into 'File'.
Support also of grab_image_async() (same behaviour as grab_image()).
Images within a image sequence are allowed to have different image sizes und bitdepths.

Revision 1.27 (Mar 29, 1999):

HALCON 5.2 version of the interface (included in the HALCON 5.2 CD).
Automatic restart from the beginning in a sequence file when end is reached (looping).

Revision 1.26 (Mar 28, 1999):

New parameter 'revision'.

Last modified: Thu Jun 5 09:09:03 CEST 2003