How to segment a region in matlab

I want to segment a region from an image in MATLAB and display it in a different image file.

I have tried segmenting it but failed. I want to segment the region from 200:400(i.e. only the regions those are yellow and green)

I = imread('Intensity1.jpg');
    imshow(I)
    hold on

    mask = false(size(I));
    mask(200:400) = true;
visboundaries(mask,'Color','b');