void Eigenbackground::UpdateHistory(int frame_num, const RgbImage& new_frame)
{
if(frame_num < m_params.HistorySize())
{
CvMat src_row;
cvGetRow(m_pcaData, &src_row, frame_num);
cvReshape(&src_row, &src_row, 3, new_frame.Ptr()->height);
cvCopy(new_frame.Ptr(), &src_row);
}
}
void Eigenbackground::Subtract(int frame_num, const RgbImage& data,
BwImage& low_threshold_mask, BwImage& high_threshold_mask)
{
// create eigenbackground
if(frame_num == m_params.HistorySize())
{
// create the eigenspace
m_pcaAvg = cvCreateMat( 1, m_pcaData->cols, CV_32F );
m_eigenValues = cvCreateMat( m_pcaData->rows, 1, CV_32F );
m_eigenVectors = cvCreateMat( m_pcaData->rows, m_pcaData->cols, CV_32F );
cvCalcPCA(m_pcaData, m_pcaAvg, m_eigenValues, m_eigenVectors, CV_PCA_DATA_AS_ROW);
int index = 0;
for(unsigned int r = 0; r < m_params.Height(); ++r)
{
for(unsigned int c = 0; c < m_params.Width(); ++c)
{
for(int ch = 0; ch < m_background.Ptr()->nChannels; ++ch)
{
m_background(r,c,0) = static_cast<unsigned char>(cvmGet(m_pcaAvg,0,index)+0.5);
index++;
}
}
}
}
if(frame_num >= m_params.HistorySize())
{
// project new image into the eigenspace
int w = data.Ptr()->width;
int h = data.Ptr()->height;
int ch = data.Ptr()->nChannels;
CvMat* dataPt = cvCreateMat(1, w*h*ch, CV_8UC1);
CvMat data_row;
cvGetRow(dataPt, &data_row, 0);
cvReshape(&data_row, &data_row, 3, data.Ptr()->height);
cvCopy(data.Ptr(), &data_row);
CvMat* proj = cvCreateMat(1, m_params.EmbeddedDim(), CV_32F);
cvProjectPCA(dataPt, m_pcaAvg, m_eigenVectors, proj);
// reconstruct point
CvMat* result = cvCreateMat(1, m_pcaData->cols, CV_32F);
cvBackProjectPCA(proj, m_pcaAvg, m_eigenVectors, result);
// calculate Euclidean distance between new image and its eigenspace projection
int index = 0;
for(unsigned int r = 0; r < m_params.Height(); ++r)
{
for(unsigned int c = 0; c < m_params.Width(); ++c)
{
double dist = 0;
bool bgLow = true;
bool bgHigh = true;
for(int ch = 0; ch < 3; ++ch)
{
dist = (data(r,c,ch) - cvmGet(result,0,index))*(data(r,c,ch) - cvmGet(result,0,index));
if(dist > m_params.LowThreshold())
bgLow = false;
if(dist > m_params.HighThreshold())
bgHigh = false;
index++;
}
if(!bgLow)
{
low_threshold_mask(r,c) = FOREGROUND;
}
else
{
low_threshold_mask(r,c) = BACKGROUND;
}
if(!bgHigh)
{
high_threshold_mask(r,c) = FOREGROUND;
}
else
{
high_threshold_mask(r,c) = BACKGROUND;
}
}
}
cvReleaseMat(&result);
cvReleaseMat(&proj);
cvReleaseMat(&dataPt);
}
else
{
// set entire image to background since there is not enough information yet
// to start performing background subtraction
for(unsigned int r = 0; r < m_params.Height(); ++r)
{
for(unsigned int c = 0; c < m_params.Width(); ++c)
{
low_threshold_mask(r,c) = BACKGROUND;
high_threshold_mask(r,c) = BACKGROUND;
}
}
}
UpdateHistory(frame_num, data);
}
