fixed grabCut: moved to double precision and added the noise to avoid zero determinant of covariance matrix

This commit is contained in:
Maria Dimashova 2010-11-10 15:24:11 +00:00
parent 0acc00bf62
commit f76d393910

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@ -51,6 +51,35 @@ This is implementation of image segmentation algorithm GrabCut described in
Carsten Rother, Vladimir Kolmogorov, Andrew Blake. Carsten Rother, Vladimir Kolmogorov, Andrew Blake.
*/ */
class Noise3DGenerator
{
public:
Noise3DGenerator( float var=0.1f ) : rng(theRNG())
{
var = std::min( std::max( 0.01f, var ), 1.f ) ;
double meanData[] = { 0., 0., 0. };
double covData[] = { var, 0., 0.,
0., var, 0.,
0., 0., var };
Mat( 1, 3, CV_64FC1, meanData ).copyTo( mean );
Mat( 3, 3, CV_64FC1, covData ).copyTo( cov );
}
Vec3d generateNoise()
{
Mat noise( 1, 3, CV_64FC1 );
rng.fill( noise, RNG::NORMAL, Scalar::all(0.0), Scalar(1.0) );
noise = noise * cov + mean;
return Vec3d( noise.ptr<double>() );
}
private:
RNG& rng;
Mat mean;
Mat cov;
};
/* /*
GMM - Gaussian Mixture Model GMM - Gaussian Mixture Model
*/ */
@ -60,27 +89,30 @@ public:
static const int componentsCount = 5; static const int componentsCount = 5;
GMM( Mat& _model ); GMM( Mat& _model );
float operator()( Vec3f color ) const; double operator()( const Vec3d color ) const;
float operator()( int ci, Vec3f color ) const; double operator()( int ci, const Vec3d color ) const;
int whichComponent( Vec3f color ) const; int whichComponent( const Vec3d color ) const;
void initLearning(); void initLearning();
void addSample( int ci, Vec3f color ); void addSample( int ci, const Vec3d color );
void endLearning(); void endLearning();
private: private:
void calcInverseCovAndDeterm( int ci ); void calcInverseCovAndDeterm( int ci );
Mat model; Mat model;
float* coefs; double* coefs;
float* mean; double* mean;
float* cov; double* cov;
float inverseCovs[componentsCount][3][3]; double inverseCovs[componentsCount][3][3];
float covDeterms[componentsCount]; double covDeterms[componentsCount];
float sums[componentsCount][3]; double sums[componentsCount][3];
float prods[componentsCount][3][3]; double prods[componentsCount][3][3];
int sampleCounts[componentsCount]; int sampleCounts[componentsCount];
int totalSampleCount; int totalSampleCount;
Noise3DGenerator noiseGenerator;
}; };
GMM::GMM( Mat& _model ) GMM::GMM( Mat& _model )
@ -88,15 +120,15 @@ GMM::GMM( Mat& _model )
const int modelSize = 3/*mean*/ + 9/*covariance*/ + 1/*component weight*/; const int modelSize = 3/*mean*/ + 9/*covariance*/ + 1/*component weight*/;
if( _model.empty() ) if( _model.empty() )
{ {
_model.create( 1, modelSize*componentsCount, CV_32FC1 ); _model.create( 1, modelSize*componentsCount, CV_64FC1 );
_model.setTo(Scalar(0)); _model.setTo(Scalar(0));
} }
else if( (_model.type() != CV_32FC1) || (_model.rows != 1) || (_model.cols != modelSize*componentsCount) ) else if( (_model.type() != CV_64FC1) || (_model.rows != 1) || (_model.cols != modelSize*componentsCount) )
CV_Error( CV_StsBadArg, "_model must have CV_32FC1 type, rows == 1 and cols == 13*componentsCount" ); CV_Error( CV_StsBadArg, "_model must have CV_64FC1 type, rows == 1 and cols == 13*componentsCount" );
model = _model; model = _model;
coefs = model.ptr<float>(0); coefs = model.ptr<double>(0);
mean = coefs + componentsCount; mean = coefs + componentsCount;
cov = mean + 3*componentsCount; cov = mean + 3*componentsCount;
@ -105,41 +137,39 @@ GMM::GMM( Mat& _model )
calcInverseCovAndDeterm( ci ); calcInverseCovAndDeterm( ci );
} }
float GMM::operator()( Vec3f color ) const double GMM::operator()( const Vec3d color ) const
{ {
float res = 0; double res = 0;
for( int ci = 0; ci < componentsCount; ci++ ) for( int ci = 0; ci < componentsCount; ci++ )
res += coefs[ci] * (*this)(ci, color ); res += coefs[ci] * (*this)(ci, color );
return res; return res;
} }
float GMM::operator()( int ci, Vec3f color ) const double GMM::operator()( int ci, const Vec3d color ) const
{ {
float res = 0; double res = 0;
if( coefs[ci] > 0 ) if( coefs[ci] > 0 )
{ {
if( covDeterms[ci] > std::numeric_limits<float>::epsilon() ) CV_Assert( covDeterms[ci] > std::numeric_limits<double>::epsilon() );
{ Vec3d diff = color;
Vec3f diff = color; double* m = mean + 3*ci;
float* m = mean + 3*ci; diff[0] -= m[0]; diff[1] -= m[1]; diff[2] -= m[2];
diff[0] -= m[0]; diff[1] -= m[1]; diff[2] -= m[2]; double mult = diff[0]*(diff[0]*inverseCovs[ci][0][0] + diff[1]*inverseCovs[ci][1][0] + diff[2]*inverseCovs[ci][2][0])
float mult = diff[0]*(diff[0]*inverseCovs[ci][0][0] + diff[1]*inverseCovs[ci][1][0] + diff[2]*inverseCovs[ci][2][0]) + diff[1]*(diff[0]*inverseCovs[ci][0][1] + diff[1]*inverseCovs[ci][1][1] + diff[2]*inverseCovs[ci][2][1])
+ diff[1]*(diff[0]*inverseCovs[ci][0][1] + diff[1]*inverseCovs[ci][1][1] + diff[2]*inverseCovs[ci][2][1]) + diff[2]*(diff[0]*inverseCovs[ci][0][2] + diff[1]*inverseCovs[ci][1][2] + diff[2]*inverseCovs[ci][2][2]);
+ diff[2]*(diff[0]*inverseCovs[ci][0][2] + diff[1]*inverseCovs[ci][1][2] + diff[2]*inverseCovs[ci][2][2]); res = 1.0f/sqrt(covDeterms[ci]) * exp(-0.5f*mult);
res = 1.0f/sqrt(covDeterms[ci]) * exp(-0.5f*mult);
}
} }
return res; return res;
} }
int GMM::whichComponent( Vec3f color ) const int GMM::whichComponent( const Vec3d color ) const
{ {
int k = 0; int k = 0;
float max = 0; double max = 0;
for( int ci = 0; ci < componentsCount; ci++ ) for( int ci = 0; ci < componentsCount; ci++ )
{ {
float p = (*this)( ci, color ); double p = (*this)( ci, color );
if( p > max ) if( p > max )
{ {
k = ci; k = ci;
@ -162,12 +192,13 @@ void GMM::initLearning()
totalSampleCount = 0; totalSampleCount = 0;
} }
void GMM::addSample( int ci, Vec3f color ) void GMM::addSample( int ci, const Vec3d color )
{ {
sums[ci][0] += color[0]; sums[ci][1] += color[1]; sums[ci][2] += color[2]; Vec3d nClr = color + noiseGenerator.generateNoise();
prods[ci][0][0] += color[0]*color[0]; prods[ci][0][1] += color[0]*color[1]; prods[ci][0][2] += color[0]*color[2]; sums[ci][0] += nClr[0]; sums[ci][1] += nClr[1]; sums[ci][2] += nClr[2];
prods[ci][1][0] += color[1]*color[0]; prods[ci][1][1] += color[1]*color[1]; prods[ci][1][2] += color[1]*color[2]; prods[ci][0][0] += nClr[0]*nClr[0]; prods[ci][0][1] += nClr[0]*nClr[1]; prods[ci][0][2] += nClr[0]*nClr[2];
prods[ci][2][0] += color[2]*color[0]; prods[ci][2][1] += color[2]*color[1]; prods[ci][2][2] += color[2]*color[2]; prods[ci][1][0] += nClr[1]*nClr[0]; prods[ci][1][1] += nClr[1]*nClr[1]; prods[ci][1][2] += nClr[1]*nClr[2];
prods[ci][2][0] += nClr[2]*nClr[0]; prods[ci][2][1] += nClr[2]*nClr[1]; prods[ci][2][2] += nClr[2]*nClr[2];
sampleCounts[ci]++; sampleCounts[ci]++;
totalSampleCount++; totalSampleCount++;
} }
@ -181,12 +212,12 @@ void GMM::endLearning()
coefs[ci] = 0; coefs[ci] = 0;
else else
{ {
coefs[ci] = (float)n/totalSampleCount; coefs[ci] = (double)n/totalSampleCount;
float* m = mean + 3*ci; double* m = mean + 3*ci;
m[0] = sums[ci][0]/n; m[1] = sums[ci][1]/n; m[2] = sums[ci][2]/n; m[0] = sums[ci][0]/n; m[1] = sums[ci][1]/n; m[2] = sums[ci][2]/n;
float* c = cov + 9*ci; double* c = cov + 9*ci;
c[0] = prods[ci][0][0]/n - m[0]*m[0]; c[1] = prods[ci][0][1]/n - m[0]*m[1]; c[2] = prods[ci][0][2]/n - m[0]*m[2]; c[0] = prods[ci][0][0]/n - m[0]*m[0]; c[1] = prods[ci][0][1]/n - m[0]*m[1]; c[2] = prods[ci][0][2]/n - m[0]*m[2];
c[3] = prods[ci][1][0]/n - m[1]*m[0]; c[4] = prods[ci][1][1]/n - m[1]*m[1]; c[5] = prods[ci][1][2]/n - m[1]*m[2]; c[3] = prods[ci][1][0]/n - m[1]*m[0]; c[4] = prods[ci][1][1]/n - m[1]*m[1]; c[5] = prods[ci][1][2]/n - m[1]*m[2];
c[6] = prods[ci][2][0]/n - m[2]*m[0]; c[7] = prods[ci][2][1]/n - m[2]*m[1]; c[8] = prods[ci][2][2]/n - m[2]*m[2]; c[6] = prods[ci][2][0]/n - m[2]*m[0]; c[7] = prods[ci][2][1]/n - m[2]*m[1]; c[8] = prods[ci][2][2]/n - m[2]*m[2];
@ -200,22 +231,20 @@ void GMM::calcInverseCovAndDeterm( int ci )
{ {
if( coefs[ci] > 0 ) if( coefs[ci] > 0 )
{ {
float *c = cov + 9*ci; double *c = cov + 9*ci;
float dtrm = double dtrm =
covDeterms[ci] = c[0]*(c[4]*c[8]-c[5]*c[7]) - c[1]*(c[3]*c[8]-c[5]*c[6]) + c[2]*(c[3]*c[7]-c[4]*c[6]); covDeterms[ci] = c[0]*(c[4]*c[8]-c[5]*c[7]) - c[1]*(c[3]*c[8]-c[5]*c[6]) + c[2]*(c[3]*c[7]-c[4]*c[6]);
if( dtrm > std::numeric_limits<float>::epsilon() ) CV_Assert( dtrm > std::numeric_limits<double>::epsilon() );
{ inverseCovs[ci][0][0] = (c[4]*c[8] - c[5]*c[7]) / dtrm;
inverseCovs[ci][0][0] = (c[4]*c[8] - c[5]*c[7]) / dtrm; inverseCovs[ci][1][0] = -(c[3]*c[8] - c[5]*c[6]) / dtrm;
inverseCovs[ci][1][0] = -(c[3]*c[8] - c[5]*c[6]) / dtrm; inverseCovs[ci][2][0] = (c[3]*c[7] - c[4]*c[6]) / dtrm;
inverseCovs[ci][2][0] = (c[3]*c[7] - c[4]*c[6]) / dtrm; inverseCovs[ci][0][1] = -(c[1]*c[8] - c[2]*c[7]) / dtrm;
inverseCovs[ci][0][1] = -(c[1]*c[8] - c[2]*c[7]) / dtrm; inverseCovs[ci][1][1] = (c[0]*c[8] - c[2]*c[6]) / dtrm;
inverseCovs[ci][1][1] = (c[0]*c[8] - c[2]*c[6]) / dtrm; inverseCovs[ci][2][1] = -(c[0]*c[7] - c[1]*c[6]) / dtrm;
inverseCovs[ci][2][1] = -(c[0]*c[7] - c[1]*c[6]) / dtrm; inverseCovs[ci][0][2] = (c[1]*c[5] - c[2]*c[4]) / dtrm;
inverseCovs[ci][0][2] = (c[1]*c[5] - c[2]*c[4]) / dtrm; inverseCovs[ci][1][2] = -(c[0]*c[5] - c[2]*c[3]) / dtrm;
inverseCovs[ci][1][2] = -(c[0]*c[5] - c[2]*c[3]) / dtrm; inverseCovs[ci][2][2] = (c[0]*c[4] - c[1]*c[3]) / dtrm;
inverseCovs[ci][2][2] = (c[0]*c[4] - c[1]*c[3]) / dtrm;
}
} }
} }
@ -223,32 +252,32 @@ void GMM::calcInverseCovAndDeterm( int ci )
Calculate beta - parameter of GrabCut algorithm. Calculate beta - parameter of GrabCut algorithm.
beta = 1/(2*avg(sqr(||color[i] - color[j]||))) beta = 1/(2*avg(sqr(||color[i] - color[j]||)))
*/ */
float calcBeta( const Mat& img ) double calcBeta( const Mat& img )
{ {
float beta = 0; double beta = 0;
for( int y = 0; y < img.rows; y++ ) for( int y = 0; y < img.rows; y++ )
{ {
for( int x = 0; x < img.cols; x++ ) for( int x = 0; x < img.cols; x++ )
{ {
Vec3f color = img.at<Vec3b>(y,x); Vec3d color = img.at<Vec3b>(y,x);
if( x>0 ) // left if( x>0 ) // left
{ {
Vec3f diff = color - (Vec3f)img.at<Vec3b>(y,x-1); Vec3d diff = color - (Vec3d)img.at<Vec3b>(y,x-1);
beta += diff.dot(diff); beta += diff.dot(diff);
} }
if( y>0 && x>0 ) // upleft if( y>0 && x>0 ) // upleft
{ {
Vec3f diff = color - (Vec3f)img.at<Vec3b>(y-1,x-1); Vec3d diff = color - (Vec3d)img.at<Vec3b>(y-1,x-1);
beta += diff.dot(diff); beta += diff.dot(diff);
} }
if( y>0 ) // up if( y>0 ) // up
{ {
Vec3f diff = color - (Vec3f)img.at<Vec3b>(y-1,x); Vec3d diff = color - (Vec3d)img.at<Vec3b>(y-1,x);
beta += diff.dot(diff); beta += diff.dot(diff);
} }
if( y>0 && x<img.cols-1) // upright if( y>0 && x<img.cols-1) // upright
{ {
Vec3f diff = color - (Vec3f)img.at<Vec3b>(y-1,x+1); Vec3d diff = color - (Vec3d)img.at<Vec3b>(y-1,x+1);
beta += diff.dot(diff); beta += diff.dot(diff);
} }
} }
@ -261,46 +290,46 @@ float calcBeta( const Mat& img )
Calculate weights of noterminal vertices of graph. Calculate weights of noterminal vertices of graph.
beta and gamma - parameters of GrabCut algorithm. beta and gamma - parameters of GrabCut algorithm.
*/ */
void calcNWeights( const Mat& img, Mat& leftW, Mat& upleftW, Mat& upW, Mat& uprightW, float beta, float gamma ) void calcNWeights( const Mat& img, Mat& leftW, Mat& upleftW, Mat& upW, Mat& uprightW, double beta, double gamma )
{ {
const float gammaDivSqrt2 = gamma / std::sqrt(2.0f); const double gammaDivSqrt2 = gamma / std::sqrt(2.0f);
leftW.create( img.rows, img.cols, CV_32FC1 ); leftW.create( img.rows, img.cols, CV_64FC1 );
upleftW.create( img.rows, img.cols, CV_32FC1 ); upleftW.create( img.rows, img.cols, CV_64FC1 );
upW.create( img.rows, img.cols, CV_32FC1 ); upW.create( img.rows, img.cols, CV_64FC1 );
uprightW.create( img.rows, img.cols, CV_32FC1 ); uprightW.create( img.rows, img.cols, CV_64FC1 );
for( int y = 0; y < img.rows; y++ ) for( int y = 0; y < img.rows; y++ )
{ {
for( int x = 0; x < img.cols; x++ ) for( int x = 0; x < img.cols; x++ )
{ {
Vec3f color = img.at<Vec3b>(y,x); Vec3d color = img.at<Vec3b>(y,x);
if( x-1>=0 ) // left if( x-1>=0 ) // left
{ {
Vec3f diff = color - (Vec3f)img.at<Vec3b>(y,x-1); Vec3d diff = color - (Vec3d)img.at<Vec3b>(y,x-1);
leftW.at<float>(y,x) = gamma * exp(-beta*diff.dot(diff)); leftW.at<double>(y,x) = gamma * exp(-beta*diff.dot(diff));
} }
else else
leftW.at<float>(y,x) = 0; leftW.at<double>(y,x) = 0;
if( x-1>=0 && y-1>=0 ) // upleft if( x-1>=0 && y-1>=0 ) // upleft
{ {
Vec3f diff = color - (Vec3f)img.at<Vec3b>(y-1,x-1); Vec3d diff = color - (Vec3d)img.at<Vec3b>(y-1,x-1);
upleftW.at<float>(y,x) = gammaDivSqrt2 * exp(-beta*diff.dot(diff)); upleftW.at<double>(y,x) = gammaDivSqrt2 * exp(-beta*diff.dot(diff));
} }
else else
upleftW.at<float>(y,x) = 0; upleftW.at<double>(y,x) = 0;
if( y-1>=0 ) // up if( y-1>=0 ) // up
{ {
Vec3f diff = color - (Vec3f)img.at<Vec3b>(y-1,x); Vec3d diff = color - (Vec3d)img.at<Vec3b>(y-1,x);
upW.at<float>(y,x) = gamma * exp(-beta*diff.dot(diff)); upW.at<double>(y,x) = gamma * exp(-beta*diff.dot(diff));
} }
else else
upW.at<float>(y,x) = 0; upW.at<double>(y,x) = 0;
if( x+1<img.cols-1 && y-1>=0 ) // upright if( x+1<img.cols-1 && y-1>=0 ) // upright
{ {
Vec3f diff = color - (Vec3f)img.at<Vec3b>(y-1,x+1); Vec3d diff = color - (Vec3d)img.at<Vec3b>(y-1,x+1);
uprightW.at<float>(y,x) = gammaDivSqrt2 * exp(-beta*diff.dot(diff)); uprightW.at<double>(y,x) = gammaDivSqrt2 * exp(-beta*diff.dot(diff));
} }
else else
uprightW.at<float>(y,x) = 0; uprightW.at<double>(y,x) = 0;
} }
} }
} }
@ -394,8 +423,8 @@ void assignGMMsComponents( const Mat& img, const Mat& mask, const GMM& bgdGMM, c
{ {
for( p.x = 0; p.x < img.cols; p.x++ ) for( p.x = 0; p.x < img.cols; p.x++ )
{ {
Vec3f color = img.at<Vec3b>(p); Vec3d color = img.at<Vec3b>(p);
compIdxs.at<int>(p) = mask.at<uchar>(p) == GC_BGD || mask.at<uchar>(p) == GC_PR_BGD ? compIdxs.at<int>(p) = mask.at<uchar>(p) == GC_BGD || mask.at<uchar>(p) == GC_PR_BGD ?
bgdGMM.whichComponent(color) : fgdGMM.whichComponent(color); bgdGMM.whichComponent(color) : fgdGMM.whichComponent(color);
} }
} }
@ -432,9 +461,9 @@ void learnGMMs( const Mat& img, const Mat& mask, const Mat& compIdxs, GMM& bgdGM
/* /*
Construct GCGraph Construct GCGraph
*/ */
void constructGCGraph( const Mat& img, const Mat& mask, const GMM& bgdGMM, const GMM& fgdGMM, float lambda, void constructGCGraph( const Mat& img, const Mat& mask, const GMM& bgdGMM, const GMM& fgdGMM, double lambda,
const Mat& leftW, const Mat& upleftW, const Mat& upW, const Mat& uprightW, const Mat& leftW, const Mat& upleftW, const Mat& upW, const Mat& uprightW,
GCGraph<float>& graph ) GCGraph<double>& graph )
{ {
int vtxCount = img.cols*img.rows, int vtxCount = img.cols*img.rows,
edgeCount = 2*(4*img.cols*img.rows - 3*(img.cols + img.rows) + 2); edgeCount = 2*(4*img.cols*img.rows - 3*(img.cols + img.rows) + 2);
@ -449,7 +478,7 @@ void constructGCGraph( const Mat& img, const Mat& mask, const GMM& bgdGMM, const
Vec3b color = img.at<Vec3b>(p); Vec3b color = img.at<Vec3b>(p);
// set t-weights // set t-weights
float fromSource, toSink; double fromSource, toSink;
if( mask.at<uchar>(p) == GC_PR_BGD || mask.at<uchar>(p) == GC_PR_FGD ) if( mask.at<uchar>(p) == GC_PR_BGD || mask.at<uchar>(p) == GC_PR_FGD )
{ {
fromSource = -log( bgdGMM(color) ); fromSource = -log( bgdGMM(color) );
@ -470,22 +499,22 @@ void constructGCGraph( const Mat& img, const Mat& mask, const GMM& bgdGMM, const
// set n-weights // set n-weights
if( p.x>0 ) if( p.x>0 )
{ {
float w = leftW.at<float>(p); double w = leftW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-1, w, w ); graph.addEdges( vtxIdx, vtxIdx-1, w, w );
} }
if( p.x>0 && p.y>0 ) if( p.x>0 && p.y>0 )
{ {
float w = upleftW.at<float>(p); double w = upleftW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols-1, w, w ); graph.addEdges( vtxIdx, vtxIdx-img.cols-1, w, w );
} }
if( p.y>0 ) if( p.y>0 )
{ {
float w = upW.at<float>(p); double w = upW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols, w, w ); graph.addEdges( vtxIdx, vtxIdx-img.cols, w, w );
} }
if( p.x<img.cols-1 && p.y>0 ) if( p.x<img.cols-1 && p.y>0 )
{ {
float w = uprightW.at<float>(p); double w = uprightW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols+1, w, w ); graph.addEdges( vtxIdx, vtxIdx-img.cols+1, w, w );
} }
} }
@ -495,7 +524,7 @@ void constructGCGraph( const Mat& img, const Mat& mask, const GMM& bgdGMM, const
/* /*
Estimate segmentation using MaxFlow algorithm Estimate segmentation using MaxFlow algorithm
*/ */
void estimateSegmentation( GCGraph<float>& graph, Mat& mask ) void estimateSegmentation( GCGraph<double>& graph, Mat& mask )
{ {
graph.maxFlow(); graph.maxFlow();
Point p; Point p;
@ -541,16 +570,16 @@ void cv::grabCut( const Mat& img, Mat& mask, Rect rect,
if( mode == GC_EVAL ) if( mode == GC_EVAL )
checkMask( img, mask ); checkMask( img, mask );
const float gamma = 50; const double gamma = 50;
const float lambda = 9*gamma; const double lambda = 9*gamma;
const float beta = calcBeta( img ); const double beta = calcBeta( img );
Mat leftW, upleftW, upW, uprightW; Mat leftW, upleftW, upW, uprightW;
calcNWeights( img, leftW, upleftW, upW, uprightW, beta, gamma ); calcNWeights( img, leftW, upleftW, upW, uprightW, beta, gamma );
for( int i = 0; i < iterCount; i++ ) for( int i = 0; i < iterCount; i++ )
{ {
GCGraph<float> graph; GCGraph<double> graph;
assignGMMsComponents( img, mask, bgdGMM, fgdGMM, compIdxs ); assignGMMsComponents( img, mask, bgdGMM, fgdGMM, compIdxs );
learnGMMs( img, mask, compIdxs, bgdGMM, fgdGMM ); learnGMMs( img, mask, compIdxs, bgdGMM, fgdGMM );
constructGCGraph(img, mask, bgdGMM, fgdGMM, lambda, leftW, upleftW, upW, uprightW, graph ); constructGCGraph(img, mask, bgdGMM, fgdGMM, lambda, leftW, upleftW, upW, uprightW, graph );