How to better segment out and label brown-colored lymphatic vessels on a histology image?

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How to better segment out and label brown-colored lymphatic vessels on a histology image?

Need to choose a proper conversion, segmentation, labelling methods and respective image processing libraries.

I have tried Java Open CV code:

    package javaopencvapp;
    import org.opencv.core.Core;
    import org.opencv.core.Mat;
    import org.opencv.core.CvType; 
    import org.opencv.core.Scalar;
    import javaopencvapp.ImageViewer;
    import org.opencv.core.Mat;
    import org.opencv.imgcodecs.Imgcodecs;
    import org.opencv.imgproc.Imgproc;

    public class JavaOpenCVapp {

    static{ System.loadLibrary(Core.NATIVE_LIBRARY_NAME); }
    public static void main(String[] args) throws Exception {
    String filePath = "src/images/imth2.tif";
    Mat newImage = Imgcodecs.imread(filePath);

            Imgproc.threshold(newImage, newImage, 172, 179.0, Imgproc.THRESH_BINARY);
           //* Imgproc.threshold(newImage, newImage, 0, 125, Imgproc.THRESH_BINARY + Imgproc.THRESH_OTSU);
           //*  Imgproc.adaptiveThreshold(newImage, newImage, 255, Imgproc.ADAPTIVE_THRESH_GAUSSIAN_C, Imgproc.THRESH_BINARY, 11, 2); 
      //* Imgproc.adaptiveThreshold(newImage,newImage, 255, Imgproc.ADAPTIVE_THRESH_MEAN_C,Imgproc. THRESH_BINARY, 15, 40);

    if(newImage.dataAddr()==0){
        System.out.println("Couldn't open file " + filePath);
    }else{
        ImageViewer imageViewer;
                    imageViewer = new ImageViewer();
        imageViewer.show(newImage, "Loaded image");
    }
}