Estimate the background and return the foreground region.

::run_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 grayvalue is computed using the values of the current data set and its stored background image and the current image (PresentImage). By comparison to the threshold (fixed or adaptive, see ::create_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_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_esti) can be lowered. The foreground region returned by ::run_bg_esti then has to be enlarged again for further processing.

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

/* read Init-Image: */
read_image(&InitImage,"Init_Image") ;
/* initialize BgEsti-Dataset with 
   fixed gains and threshold adaption */
create_bg_esti(InitImage,0.7,0.7,"fixed",0.002,0.02,
               "on",7,10,3.25,15.0,&BgEstiHandle) ;
/* read the next image in sequence: */
read_image(&Image1,"Image_1") ;
/* estimate the Background: */
run_bg_esti(Image1,&Region1,BgEstiHandle) ;
/* display the foreground region: */
disp_region(Region1,WindowHandle) ; 
/* read the next image in sequence: */
read_image(&Image2,"Image_2") ;
/* estimate the Background: */
run_bg_esti(Image2,&Region2,BgEstiHandle) ;
/* display the foreground region: */
disp_region(Region2,WindowHandle) ;
/* etc. */

::run_bg_esti returns H_MSG_TRUE if all parameters are correct.

::create_bg_esti, ::update_bg_esti

::run_bg_esti, ::give_bg_esti, ::update_bg_esti

::set_bg_esti_params, ::create_bg_esti, ::update_bg_esti, ::give_bg_esti

Background estimation