Split and label the region

Hi everyone. I wanted to split the image into half. I have used centroid function and return the value of X and Y. How to label or apply the color into the both regions as I indicated with pink line. Let say, the half (top) colored with green and the other half (bottom) with different color. Thanks

I = imread('img4.tif');
Ibw = im2bw(I);
Ibw = imfill(Ibw,'holes');
Ilabel = bwlabel(Ibw);
stat = regionprops(Ilabel,'centroid');
imshow(I); hold on;
for x = 1: numel(stat)
    plot(stat(x).Centroid(1),stat(x).Centroid(2),'ro');

 end

[Image Analyst]

I don't understand. Do you want an image where the top half is one color and the bottom half another? Or you want just the skeletons in those halves to have color and the background to remain black? Either way, why?