/*
Estimate segmentation using MaxFlow algorithm
*/
static void estimateSegmentation( GCGraph<double>& graph, InputArray _img)
{
Mat img = _img.getMat();
Mat result;
result.create(img.size(), CV_8UC1);
graph.maxFlow();
Point p;
for( p.y = 0; p.y < img.rows; p.y++ )
{
for( p.x = 0; p.x < img.cols; p.x++ )
{
if( graph.inSourceSegment( p.y*img.cols+p.x /*vertex index*/ ) )
{
//printf("1\n");
result.at<uchar>(p) = 0;
}
else
{
//printf("2\n");
result.at<uchar>(p) = 255;
}
}
}
namedWindow("Image",1);
imshow("Image", result);
waitKey();
}
/**
* Add each pixel as
* a node in a graph
*
* @param graph The graph pointer
* @param img The Source image
*
*
* @return Updates the graph
*/
void GRAPHCUT::addVertices(GCGraph<float>& graph, Mat& img)
{
for (int r = 0; r < img.rows; r++)
for (int c = 0; c < img.cols; c++)
{
graph.addVtx();
graph.addTermWeights(c + img.cols * r, img.at<float>(r, c), 1 - img.at<float>(r, c));
}
}
/*
Estimate segmentation using MaxFlow algorithm
*/
void estimateSegmentation( GCGraph<double>& graph, Mat& mask )
{
graph.maxFlow();
Point p;
for( p.y = 0; p.y < mask.rows; p.y++ )
{
for( p.x = 0; p.x < mask.cols; p.x++ )
{
if( mask.at<uchar>(p) == GC_PR_BGD || mask.at<uchar>(p) == GC_PR_FGD )
{
if( graph.inSourceSegment( p.y*mask.cols+p.x /*vertex index*/ ) )
mask.at<uchar>(p) = GC_PR_FGD;
else
mask.at<uchar>(p) = GC_PR_BGD;
}
}
}
}
/*
Construct GCGraph
*/
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,
GCGraph<double>& graph )
{
int vtxCount = img.cols*img.rows,
edgeCount = 2*(4*img.cols*img.rows - 3*(img.cols + img.rows) + 2);
graph.create(vtxCount, edgeCount);
Point p;
for( p.y = 0; p.y < img.rows; p.y++ )
{
for( p.x = 0; p.x < img.cols; p.x++)
{
// add node
int vtxIdx = graph.addVtx();
Vec3b color = img.at<Vec3b>(p);
// set t-weights
double fromSource, toSink;
if( mask.at<uchar>(p) == GC_PR_BGD || mask.at<uchar>(p) == GC_PR_FGD )
{
fromSource = -log( bgdGMM(color) );
toSink = -log( fgdGMM(color) );
}
else if( mask.at<uchar>(p) == GC_BGD )
{
fromSource = 0;
toSink = lambda;
}
else // GC_FGD
{
fromSource = lambda;
toSink = 0;
}
graph.addTermWeights( vtxIdx, fromSource, toSink );
// set n-weights
if( p.x>0 )
{
double w = leftW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-1, w, w );
}
if( p.x>0 && p.y>0 )
{
double w = upleftW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols-1, w, w );
}
if( p.y>0 )
{
double w = upW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols, w, w );
}
if( p.x<img.cols-1 && p.y>0 )
{
double w = uprightW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols+1, w, w );
}
}
}
}
/**
* Convert a Graph
* into an image
*
* @param graph The Source graph
* @param rows Image Height
* @param cols Image Width
*
*
* @return Converted Image
*/
Mat GRAPHCUT::graph2img(GCGraph<float>& graph, int rows, int cols)
{
Mat img(rows, cols, CV_32F);
for (int r = 0; r < rows; r++)
for (int c = 0; c < cols; c++)
img.at<float>(r, c) = graph.inSourceSegment(c + img.cols * r);
return img;
}
/*
Construct GCGraph
*/
static void constructGCGraph( const Mat& img, double lambda,
const Mat& leftW, const Mat& upleftW, const Mat& upW, const Mat& uprightW,
GCGraph<double>& graph )
{
int vtxCount = img.cols*img.rows,
edgeCount = 2*(4*img.cols*img.rows - 3*(img.cols + img.rows) + 2);
graph.create(vtxCount, edgeCount);
Point p;
Mat gray;
cvtColor(img, gray, CV_BGR2GRAY);
Mat bw;
threshold(gray, bw, 0, 255, CV_THRESH_BINARY | CV_THRESH_OTSU);
for( p.y = 0; p.y < img.rows; p.y++ )
{
for( p.x = 0; p.x < img.cols; p.x++)
{
// add node
int vtxIdx = graph.addVtx();
Vec3b color = img.at<Vec3b>(p);
// set t-weights
double fromSource, toSink;
if(bw.at<uchar>(p) == 0)
{
fromSource = lambda;
toSink = 0;
}
else
{
fromSource = 0;
toSink = lambda;
}
graph.addTermWeights( vtxIdx, fromSource, toSink );
// set n-weights
if( p.x>0 )
{
double w = leftW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-1, w, w );
}
if( p.x>0 && p.y>0 )
{
double w = upleftW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols-1, w, w );
}
if( p.y>0 )
{
double w = upW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols, w, w );
}
if( p.x<img.cols-1 && p.y>0 )
{
double w = uprightW.at<double>(p);
graph.addEdges( vtxIdx, vtxIdx-img.cols+1, w, w );
}
}
}
}
/**
* Add edges between
* nodes in a graph
*
* @param graph The graph pointer
* @param img The Source image
* @param neighboursWeight Neighbours influence
* @param windowSize Neighbours range
*
* @return Updates the graph
*/
void GRAPHCUT::addEdges(GCGraph<float>& graph, Mat& img, float neighboursWeight, int windowSize)
{
for (int r = windowSize; r < img.rows - windowSize; r++)
for (int c = windowSize; c < img.cols - windowSize; c++)
for (int i = -windowSize; i <= windowSize; i++)
for (int j = -windowSize; j <= windowSize; j++)
if (i != 0 || j != 0)
{
float v = abs(img.at<float>(r, c) - img.at<float>(r + i, c + j)) * neighboursWeight;
graph.addEdges(c + img.cols * r, (c + j) + img.cols * (r + i), v, v);
}
}
