Generate a HeatMap from blobs different sizes using C++

Question

I want to obtain a heatmap from the attached image. The bigger blobs will have darker(red) regions and then slowly fade to lighter blue shades. The smaller blobs will have l

Answer 1

You can simply cycle through individual blobs to find the Individual blob Color Map. Here is a sample implementation.You can use whatever Color map as you like. Hope this helps!

Mat mSource_Gray,mBlobHeatMap,mHeatMap;
mSource_Gray= imread(FileName_S.c_str(),0);

//Just making sure everything is binary
threshold(mSource_Gray,mSource_Gray,254,255,THRESH_BINARY);
imshow("Source Image",mSource_Gray);

//Finding Distance Transform
Mat mDist,mBlobDist;
distanceTransform(mSource_Gray, mDist, CV_DIST_L2, 3);
normalize(mDist, mDist, 0, 1., cv::NORM_MINMAX);
mDist.convertTo(mDist,CV_8UC1,255,0);
imshow("mDist",mDist);

vector > contours;
vector hierarchy;
/// Find contours to Mask out the Individual Contours
findContours( mSource_Gray, contours, hierarchy, RETR_TREE, CHAIN_APPROX_SIMPLE, Point(0, 0) );
/// Draw contours (Mask)
Mat mBlobMask = Mat::zeros( mSource_Gray.size(), CV_8UC1 );
for( size_t i = 0; i< contours.size(); i++ )
{
    drawContours( mBlobMask, contours, (int)i, Scalar(255), -1);
    mDist.copyTo(mBlobDist,mBlobMask);
    applyColorMap(mBlobDist,mBlobHeatMap,COLORMAP_JET);
    GaussianBlur(mBlobHeatMap,mBlobHeatMap,Size(21,21),0,0);
    mBlobHeatMap.copyTo(mHeatMap,mBlobMask);
}

imshow("mHeatMap",mHeatMap);