getBackgroundImage not in Java version? [closed]

asked 2013-11-28 18:34:02 -0500

Will Stewart gravatar image

updated 2013-11-28 18:34:46 -0500

I may be asking the obvious, but imgproc in C has getBackgroundImage in BackgroundSubtractorMOG, though I can't seem to find it in the Java version;

http://docs.opencv.org/java/org/opencv/video/BackgroundSubtractorMOG.html

I'm still relatively new and feeling my way around in OpenCV, so please excuse the novice level question.

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Closed for the following reason question is not relevant or outdated by sturkmen
close date 2020-10-07 06:08:19.976452

Comments

1

ouch! - it's fixed in master, but not in 2.4 (missing CV_WRAP tag)

if you built from src, you could just add the CV_WRAP, rerun cmake, recompile

berak gravatar imageberak ( 2013-11-29 04:07:13 -0500 )edit

Pardon my novice level, but is there a procedure that details all the required steps to do that?

And is the BackgroundSubtractorMOG2 in the same situation?

Thanks!

Will Stewart gravatar imageWill Stewart ( 2013-11-29 18:29:42 -0500 )edit
1
  • "Pardon my novice level" - no problem, that 's what this site is for, no ?
  • "is the BackgroundSubtractorMOG2 in the same situation?" - they all inherit from BackgroundSubtractor, so, if it's fixed there, all 3 can use getBackgroundImage
  • "required steps to do that?" - yes, you could fix it, but you'll have to rebuild opencv from src.

change Line 69 to:

 CV_WRAP virtual void getBackgroundImage(OutputArray backgroundImage) const;

and rebuild it as described here.

berak gravatar imageberak ( 2013-11-30 03:31:04 -0500 )edit
1

but honestly, i'm not certain, if it's worth the trouble. what do you need the bg-image for ? it's just a (very expensive, btw) visualization of the model, not needed for the actual processing.

berak gravatar imageberak ( 2013-11-30 03:33:48 -0500 )edit

@berak - is this present now in the 3.0 version?i am using 2.4.9 but getBackgroundimage is still not there. and i cant build using ndk on my system. please help

Dhara Shah gravatar imageDhara Shah ( 2014-09-03 01:56:09 -0500 )edit

well, it is present in 3.0, unfortunately i can't recommend using alpha/3.0 atm, specially for java, too many things are broken. (java for the ml module, and anything in opencv_contrib is disabled/non-functional) .

and again, i doubt, that you need the Backgroundimage at all. (as a delveloper, sure you want to take a look at it, but it has no practical value for the bg-seperation, and is a very,very expensive operation)

berak gravatar imageberak ( 2014-09-03 02:09:01 -0500 )edit

i was thinking of using the backgroundimage method in order to remove the background from the captured frame(just one frame), so that i could detect objects, i saw the alpha version in the list but then theres no sdk for android

Dhara Shah gravatar imageDhara Shah ( 2014-09-03 02:46:56 -0500 )edit

@Dhara Shah, in that case, you misunderstood the algorithm.

you are supposed to use the foreground-mask to mask out the background in your original image.

also, you need a continuous stream of images for this, it builds a background model over time.

if you only have 1 frame, you can't use it at all, better look at grabcut or similar then

berak gravatar imageberak ( 2014-09-03 02:52:33 -0500 )edit

@berak thank u for the suggestion, i will have a look at grabcut, and get back

Dhara Shah gravatar imageDhara Shah ( 2014-09-03 23:38:07 -0500 )edit