Boundary finding for human object

I want to get perfect boundary of human object, I wrote code as:

m=imread('E:\ProjectCode\35.jpg'); H=1-fspecial('gaussian',[3 3],1); sh=imfilter(m,H); figure,imshow(sh); cr = imcrop(sh,[320,100,550,750]); figure,imshow(cr);

shg=rgb2gray(cr); mask = zeros(size(shg)); mask(25:end-25,25:end-25) = 1;

figure, imshow(mask); title('Initial Contour Location'); bw = activecontour(shg,mask,300);

figure, imshow(bw); title('Segmented Image')

I am getting error:?? Undefined function or method 'activecontour' for input arguments of type 'uint8'.

Error in ==> mskbdry at 14 bw = activecontour(shg,mask,300);