finding area and centre of stones - matlab

Question

I want to find area and center of these stones.
but some of them can not be found.
here are codes
I=imread('E:/2.png');
level = graythresh(I);
BW = im2bw(I,level);
se = strel('disk',2);
bw1 = imclose(BW,se);
bw1 = imfill(BW,'holes');
bwa=bwareaopen(bw1,25);
cc = bwconncomp(bwa)
stat = regionprops(cc,'centroid','Area');
ss=[stat.Area];
imshow(I); hold on;
for x = 1: numel(stat)
plot(stat(x).Centroid(1),stat(x).Centroid(2), 'wp','MarkerSize',6,'MarkerFaceColor','b');
end
figure, imshow(bwa)
result is here:
and this is black and white pic;
some of these stones can not be separated.
is there any idea for it?

Answer 1

Erode stones until you separated them, find segments via connected components (e.g. findContours), set centers, then apply flood fill seeding floods at the centers in the original BW image (before erosion) to gracefully define segments. “Gracefully” means that floods should not ‘leak' into another (possibly connected) segment since it will be already filled with a different label. You may want to play with the parameters of floodFIll to tune up your segmentation. I did not have time to do this.
// separate stones
Mat Ibw = imread("bw.png", 0);
imshow("bw", Ibw);
int w=Ibw.cols, h=Ibw.rows;
int ERODE_SZ = 20;
Mat kernel = getStructuringElement( cv::MORPH_RECT, Size(ERODE_SZ, ERODE_SZ));
Mat Ierode;
erode(Ibw, Ierode, kernel);
imshow("erode", Ierode); imwrite("erode.png", Ierode);
vector<vector<Point> > contours;
Mat hierarchy;
Mat Icc = Ierode.clone();
findContours(Icc, contours, hierarchy, CV_RETR_LIST, CV_CHAIN_APPROX_NONE);
// find centers
Mat Icenters = Ibw.clone();
int sz = contours.size();
vector<Point> centers(sz);
for (int i=0; i<sz; ++i) {
if (i==0)
centers[i] = Point2f(0.f, 0.f);
int area = contours[i].size();
for (int j=0; j<area; j++) {
centers[i]+=contours[i][j];
}
centers[i]*=1.0/area;
circle(Icenters, centers[i], 3, 100, 3);
}
imshow("centers", Icenters);imwrite("erode.png", Ierode);
// find segments
Mat Iseg = Ibw.clone();
RNG rng( 0xFFFFFFFF );
for (int i=0; i<sz; ++i) {
floodFill(Iseg, centers[i], rng.uniform(100, 200));
circle(Iseg, centers[i], 3, 0, 1);
}
imshow("seg", Iseg); imwrite("result.png", Iseg);
waitKey();