Operator Reference

HALCON Operator Reference / Tools / Background Estimator
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run_bg_estiT_run_bg_estiRunBgEstiRunBgEstirun_bg_esti (Operator)

run_bg_estiT_run_bg_estiRunBgEstiRunBgEstirun_bg_esti — Estimate the background and return the foreground region.

Signature

Herror T_run_bg_esti(const Hobject PresentImage, Hobject* ForegroundRegion, const Htuple BgEstiHandle)

void RunBgEsti(const HObject& PresentImage, HObject* ForegroundRegion, const HTuple& BgEstiHandle)

HRegion HImage::RunBgEsti(const HBgEsti& BgEstiHandle) const

HRegion HBgEsti::RunBgEsti(const HImage& PresentImage) const

def run_bg_esti(present_image: HObject, bg_esti_handle: HHandle) -> HObject

Description

run_bg_estirun_bg_estiRunBgEstiRunBgEstirun_bg_esti adapts the background image stored in the BgEsti data set using a Kalman filter on each pixel and returns a region of the foreground (detected moving objects).

For every pixel an estimation of its gray value is computed using the values of the current data set and its stored background image and the current image (PresentImagePresentImagePresentImagepresentImagepresent_image). By comparison to the threshold (fixed or adaptive, see create_bg_esticreate_bg_estiCreateBgEstiCreateBgEsticreate_bg_esti) the pixels are classified as either foreground or background.

The background estimation processes only single-channel images. Therefore the background has to be adapted separately for every channel.

The background estimation should be used on half- or even quarter-sized images. For this, the input images (and the initialization image!) has to be reduced using zoom_image_factorzoom_image_factorZoomImageFactorZoomImageFactorzoom_image_factor. The advantage is a shorter run-time on one hand and a low-band filtering on the other. The filtering eliminates high frequency noise and results in a more reliable estimation. As a result the threshold (see create_bg_esticreate_bg_estiCreateBgEstiCreateBgEsticreate_bg_esti) can be lowered. The foreground region returned by run_bg_estirun_bg_estiRunBgEstiRunBgEstirun_bg_esti then has to be enlarged again for further processing.

Attention

The passed image (PresentImagePresentImagePresentImagepresentImagepresent_image) must have the same type and size as the background image of the current data set (initialized with create_bg_esticreate_bg_estiCreateBgEstiCreateBgEsticreate_bg_esti).

Execution Information

  • Multithreading type: reentrant (runs in parallel with non-exclusive operators).
  • Multithreading scope: global (may be called from any thread).
  • Processed without parallelization.

Parameters

PresentImagePresentImagePresentImagepresentImagepresent_image (input_object)  singlechannelimage → objectHImageHObjectHObjectHobject (byte / real)

Current image.

ForegroundRegionForegroundRegionForegroundRegionforegroundRegionforeground_region (output_object)  region → objectHRegionHObjectHObjectHobject *

Region of the detected foreground.

BgEstiHandleBgEstiHandleBgEstiHandlebgEstiHandlebg_esti_handle (input_control)  bg_estimation → HBgEsti, HTupleHHandleHTupleHtuple (handle) (IntPtr) (HHandle) (handle)

ID of the BgEsti data set.

Example (HDevelop)

* Read image for initialization:
read_image(InitImage,'xing/init')
* Initialize BgEsti dataset with
* fixed gains and threshold adaption:
create_bg_esti(InitImage,0.7,0.7,'fixed',0.002,0.02, \
               'on',7.0,10,3.25,15.0,BgEstiHandle)
* Read the next image in sequence:
read_image(Image0,'xing/xing000')
* Estimate the background:
run_bg_esti(Image0,ForegroundRegion1,BgEstiHandle)
* Display the foreground region:
dev_display (ForegroundRegion1)
* Read the next image in sequence:
read_image(Image1,'xing/xing001')
* Estimate the background:
run_bg_esti(Image1,ForegroundRegion2,BgEstiHandle)
* Display the foreground region:
dev_display (ForegroundRegion2)
* etc.

Result

run_bg_estirun_bg_estiRunBgEstiRunBgEstirun_bg_esti returns 2 ( H_MSG_TRUE) if all parameters are correct.

Possible Predecessors

create_bg_esticreate_bg_estiCreateBgEstiCreateBgEsticreate_bg_esti, update_bg_estiupdate_bg_estiUpdateBgEstiUpdateBgEstiupdate_bg_esti

Possible Successors

give_bg_estigive_bg_estiGiveBgEstiGiveBgEstigive_bg_esti, update_bg_estiupdate_bg_estiUpdateBgEstiUpdateBgEstiupdate_bg_esti

See also

set_bg_esti_paramsset_bg_esti_paramsSetBgEstiParamsSetBgEstiParamsset_bg_esti_params, create_bg_esticreate_bg_estiCreateBgEstiCreateBgEsticreate_bg_esti, update_bg_estiupdate_bg_estiUpdateBgEstiUpdateBgEstiupdate_bg_esti, give_bg_estigive_bg_estiGiveBgEstiGiveBgEstigive_bg_esti

Module

Foundation

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