Detect Edges having length greater than 50km

Hi all,

I have detected edges using Canny Edge detector. But I want to detect Edges having length greater than 50km. I have attached code. Can anyone help me to edit code to detect edges of given length?

X = cell2mat(struct2cell(load('F:\study\practise\New folder\2010\script\preprocessed2010.mat', 'Alpha')));

 for k=1:length(X)
   b=X(k).img;  
   b(b==0)=NaN;
   b (b > -5) = NaN;
   b (b < -32) = NaN;
   figure, temp1 = imagesc(b);title('Original Image') ;colormap('gray'); colorbar;
   baseFileName = sprintf('%d.jpg',k);
% %        % Specify some particular, specific folder:
       fullFileName = fullfile('E:\practise\images', baseFileName);  
       figure(gcf); % Activate the figure again.
       export_fig(fullFileName); 
       
       
  % Get edges
A = edge(b, 'canny');

 figure, temp1 = imagesc(A);title('Edge Detected Image') ;colormap('gray'); colorbar;
   baseFileName = sprintf('%dCanny.jpg',k);
 fullFileName = fullfile('E:\practise\images', baseFileName);  
       figure(gcf); % Activate the figure again.
       export_fig(fullFileName);
% 
 end

Answer 1

[Image Analyst]

You forgot to attach preprocessed2010.mat.

After you get the binary image, A, you can call bwareaopen() to extract only those blobs with area more than however many pixels 50 km is;

fiftyKm = round(50 * pixelsPerKm);
A50 = bwareaopen(A, fiftyKm);

[Nadia jabeen]

Pixel area is 30*30m. I want to extract edges having length more than 50km.

[Nadia jabeen]

I don't want to extract pixels. All edges have been extracted from bwareaopen() function.