Eigenbackground.hpp

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/****************************************************************************
*
* Eigenbackground.hpp
*
* Purpose: Implementation of the Eigenbackground background subtraction 
*					 algorithm developed by Oliver et al.
*
* Author: Donovan Parks, September 2007
*
* "A Bayesian Computer Vision System for Modeling Human Interactions"
*   Nuria Oliver, Barbara Rosario, Alex P. Pentland 2000

Example:
		Algorithms::BackgroundSubtraction::EigenbackgroundParams params;
		params.SetFrameSize(width, height);
		params.LowThreshold() = 15*15;
		params.HighThreshold() = 2*params.LowThreshold();	// Note: high threshold is used by post-processing 
		params.HistorySize() = 100;
		params.EmbeddedDim() = 20;

		Algorithms::BackgroundSubtraction::Eigenbackground bgs;
		bgs.Initalize(params);
******************************************************************************/

#ifndef _ELGAMMAL_H_
#define _ELGAMMAL_H_

#include "Bgs.hpp"

namespace Algorithms
{
namespace BackgroundSubtraction
{

// --- Parameters used by the Mean BGS algorithm ---
class EigenbackgroundParams : public BgsParams
{
public:
	float &LowThreshold() { return m_low_threshold; }
	float &HighThreshold() { return m_high_threshold; }

	int &HistorySize() { return m_history_size; }
	int &EmbeddedDim() { return m_dim; }

private:
	// A pixel will be classified as foreground if the squared distance of any
	// color channel is greater than the specified threshold
	float m_low_threshold;
	float m_high_threshold;

	int m_history_size;			// number frames used to create eigenspace
	int m_dim;							// eigenspace dimensionality
};


// --- Eigenbackground BGS algorithm ---
class Eigenbackground : public Bgs
{
public:
	Eigenbackground();
	~Eigenbackground();

	void Initalize(const BgsParams& param);

	void InitModel(const RgbImage& data);
	void Subtract(int frame_num, const RgbImage& data,  
									BwImage& low_threshold_mask, BwImage& high_threshold_mask);	
	void Update(int frame_num, const RgbImage& data,  const BwImage& update_mask);

	RgbImage* Background() { return &m_background; }

private:
	void UpdateHistory(int frameNum, const RgbImage& newFrame);

	EigenbackgroundParams m_params;
	
	CvMat* m_pcaData;
	CvMat* m_pcaAvg;
	CvMat* m_eigenValues; 
  CvMat* m_eigenVectors;

	RgbImage m_background;
};

};
};

#endif