MATLAB: How to find the topmost, bottomost, leftmost and rightmost endpoints of a skeleton of a binary image? Please help.

bwmorphendpointsImage Processing Toolboxskelskeletonskeletonization

skltn = bwmorph(binaryImage, 'skel', Inf);  %getting skeleton of binary image
endpts = bwmorph(skltn, 'endpoints');       %getting enpoints of 'skltn'
[node_x, node_y] = find(endpoints==1);      %getting the x and y coordinates of the endpoints in
                                            %node_x and node_y respectively
%Now, how do I find the topmost, bottomost, leftmost and rightmost endpoints? Please help.

Best Answer

You really messed on on find. find() does not return x and y in that order -- it returns row and column (y and x) in that order. After that, just use min and max

[node_y, node_x] = find(endpoints==1);      %getting the x and y coordinates of the endpoints in
                                            %node_x and node_y respectively
% Get top row which is the smallest y value
yTopRow = min(node_y);
% Get bottom row which is the largest y value
yBottomRow = max(node_y);
% Get left column which is the smallest x value
xLeftColumn = min(node_x);
% Get right column which is the largest x value
xRightColumn = max(node_x);

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This is one way to go about doing it. (x is from left to right, and y is from top to bottom.)

dirt_grid =[  0     1     1     0     1
              1     1     0     0     1
              1     1     1     0     0];
base_location_is_zero = false;
while ~base_location_is_zero
      try
          isok = 0;
          while ~isok
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                  isok = 1;
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          isok = 0;
          while ~isok
              base_station_y = input('Enter an y co-ordinate for the base station: ' );
              if ~ismember(base_station_y, 1:size(dirt_grid,1))
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      end
end;
disp('Everything is ok!');

Best Answer

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