Try this.
GRAY=imread('204.jpg');
threshold = graythresh(GRAY);
BW = im2bw(GRAY, threshold);
%%Find Coordinates of images and smooth
[y,x]=find(BW==1);
win=15;
y=smooth(x,y,win);
%%interpolate
[x, index] = unique(x);
xq=1:256
yq = interp1(x, y2(index), xq,'linear','extrap');
%%Create figure from plot
out=zeros(size(BW));
out(sub2ind(size(GRAY),round(yq'),xq'))=1;
%%Plot
figure;
subplot(1,2,1)
imshow(out);
title('new')
subplot(1,2,2)
imshow(GRAY);
title('original')
