How can I get back the original image of the segmented area after using active contour? the background is still black but the segmented area fills with the original colour image.

clc clear all; close all; I = imread('B1_51.tif'); I=rgb2gray(I); imshow(I)

    str = 'Click to select initial contour location. Double-click to confirm and proceed.';
    title(str,'Color','b','FontSize',12);
    disp(sprintf('\nNote: Click close to object boundaries for more accurate result.'));

    mask = roipoly;

    figure, imshow(mask)
    title('Initial MASK');

    maxIterations = 200; 
    bw = activecontour(I, mask, maxIterations, 'Chan-Vese');

    figure, imshow(bw)
    title('Segmented Image')
please give me some idea and comment about this!  thank you.