BackgroundSubtractorKNN

Objective-C

@interface BackgroundSubtractorKNN : BackgroundSubtractor

Swift

class BackgroundSubtractorKNN : BackgroundSubtractor

K-nearest neighbours - based Background/Foreground Segmentation Algorithm.

The class implements the K-nearest neighbours background subtraction described in CITE: Zivkovic2006 . Very efficient if number of foreground pixels is low.

Member of Video

Methods

  • Returns the shadow detection flag

     If true, the algorithm detects shadows and marks them. See createBackgroundSubtractorKNN for
 details.

    Declaration

    Objective-C

    - (BOOL)getDetectShadows;

    Swift

    func getDetectShadows() -> Bool

  • Returns the threshold on the squared distance between the pixel and the sample

     The threshold on the squared distance between the pixel and the sample to decide whether a pixel is
 close to a data sample.

    Declaration

    Objective-C

    - (double)getDist2Threshold;

    Swift

    func getDist2Threshold() -> Double

  • Returns the shadow threshold

     A shadow is detected if pixel is a darker version of the background. The shadow threshold (Tau in
 the paper) is a threshold defining how much darker the shadow can be. Tau= 0.5 means that if a pixel
 is more than twice darker then it is not shadow. See Prati, Mikic, Trivedi and Cucchiara,

    Detecting Moving Shadows…*, IEEE PAMI,2003.

    Declaration

    Objective-C

    - (double)getShadowThreshold;

    Swift

    func getShadowThreshold() -> Double

  • Returns the number of last frames that affect the background model

    Declaration

    Objective-C

    - (int)getHistory;

    Swift

    func getHistory() -> Int32

  • Returns the number of data samples in the background model

    Declaration

    Objective-C

    - (int)getNSamples;

    Swift

    func getNSamples() -> Int32

  • Returns the shadow value

     Shadow value is the value used to mark shadows in the foreground mask. Default value is 127. Value 0
 in the mask always means background, 255 means foreground.

    Declaration

    Objective-C

    - (int)getShadowValue;

    Swift

    func getShadowValue() -> Int32

  • Returns the number of neighbours, the k in the kNN.

     K is the number of samples that need to be within dist2Threshold in order to decide that that
 pixel is matching the kNN background model.

    Declaration

    Objective-C

    - (int)getkNNSamples;

    Swift

    func getkNNSamples() -> Int32

  • Enables or disables shadow detection

    Declaration

    Objective-C

    - (void)setDetectShadows:(BOOL)detectShadows;

    Swift

    func setDetectShadows(detectShadows: Bool)

  • Sets the threshold on the squared distance

    Declaration

    Objective-C

    - (void)setDist2Threshold:(double)_dist2Threshold;

    Swift

    func setDist2Threshold(_dist2Threshold: Double)

  • Sets the number of last frames that affect the background model

    Declaration

    Objective-C

    - (void)setHistory:(int)history;

    Swift

    func setHistory(history: Int32)

  • Sets the number of data samples in the background model.

     The model needs to be reinitalized to reserve memory.

    Declaration

    Objective-C

    - (void)setNSamples:(int)_nN;

    Swift

    func setNSamples(_nN: Int32)

  • Sets the shadow threshold

    Declaration

    Objective-C

    - (void)setShadowThreshold:(double)threshold;

    Swift

    func setShadowThreshold(threshold: Double)

  • Sets the shadow value

    Declaration

    Objective-C

    - (void)setShadowValue:(int)value;

    Swift

    func setShadowValue(value: Int32)

  • Sets the k in the kNN. How many nearest neighbours need to match.

    Declaration

    Objective-C

    - (void)setkNNSamples:(int)_nkNN;

    Swift

    func setkNNSamples(_nkNN: Int32)