问如何通过matlab中的边缘点绘制图像的光滑边界

EN

img = rgb2gray(imread('1.jpg')); % Read image
img = img > 0.5;                 % Threshold to get binary image
% Get last row where there is a 1 pixel in the image for each column
lastrow = max(repmat((1:size(img,1))', 1, size(img,2)).*img,[],1);
res = 30;                        % Pixel resolution for line averaging
% Ensure res divides num. columns by padding the end of the vector
lastrowpadded = [lastrow, NaN(1, res - mod(numel(lastrow),res))]; 
% Reshape into columns of length 'res', then get the max row number
lastrow2 = max(reshape(lastrowpadded,res,[]),[],1);
% Plots
imshow(img); 
hold on
plot(1:size(img,2), lastrow, '.')
plot(res/2:res:size(lastrowpadded,2)-res/2, lastrow2, 'linewidth', 1.5)
hold off
legend('lowest points', 'smoothed lowest points')

[X,Y] = find(img); % After thresholding image as before, get X,Y coords
K = convhull(X,Y); % Get convex hull indices
imshow(img)        % Show image
hold on    
plot(Y(K),X(K),'linewidth',1.5) % Plot convex hull