bounding box around canny edge detecter

i have detected edges using canny edge detecter now i want to make a bounding box around the object to detect it how can i do that i have used the below code to make a bounding box but it just changes the color of the edges not making a bounding box

if true
  % %this program will make a yellow clour on edges
% [B,L] = bwboundaries(F, 'noholes');
% figure; imshow(F); hold on;
% for k = 1:length(B),
%    boundary = B{k};
%    plot(boundary(:,2),boundary(:,1),'w','LineWidth',2);
% end
end

[ahmed SHAH]

after applying you code nothing happens in image

 if true
    %
A = imread('shuttle.jpg');
%// Some pre-processing. Treshold image and dilate it.
B = im2bw(A,.85);
%// Detect edges
F = edge(B,'Canny');
% F=~F;
figure;
imshow(F);
hold on;
[B,L] = bwboundaries(F, 'noholes');
x = boundary(:,2);
y = boundary(:,1);
x1 = min(x);
x2 = max(x);
y1 = min(y);
y2 = max(y);
xBox = [x1, x2, x2, x1, x1];
yBox = [y1, y1, y2, y2, y1];
% Plot boundary
plot(x, y, 'm-', 'LineWidth' ,2);
% Plot bounding box.
figure;
imshow(F);
hold on;
plot(xBox, yBox, 'y-',  'LineWidth' ,2);

end

Answer 1

[Image Analyst]

To get bounding boxes, you'll either have to use regionprops, or use max and min on the x and y vectors:

x = boundary(:,2);
y = boundary(:,1);
x1 = min(x);
x2 = max(x);
y1 = min(y);
y2 = max(y);
xBox = [x1, x2, x2, x1, x1];
yBox = [y1, y1, y2, y2, y1];
% Plot boundary
plot(x, y, 'm-', 'LineWidth' ,2);
% Plot bounding box.
hold on;
plot(xBox, yBox, 'y-',  'LineWidth' ,2);

[ahmed SHAH]

further modiying my own code i get a image with bounding box on left side in image but i want box to be small like its detecting the object in the right pic

% A = imread('shuttle.jpg');
%// Some pre-processing. Treshold image and dilate it.
B = im2bw(A,.85);
%// Detect edges
F = edge(B,'Canny');
F=~F;
figure;
imshow(F);
hold on;
% % this program will make a yellow clour on edges
[B,L] = bwboundaries(F, 'noholes');
figure; 
imshow(F);
hold on;
for k = 1:length(B),
 boundary = B{k};
 plot(boundary(:,2),boundary(:,1),'b','LineWidth',2);
end

[Image Analyst]

Evidently you have some edges out there at the boundary of the image. You'll need to get rid of those. Maybe it's because you, for some reason, inverted the edge image before computing boundaries. I never would have done that. Attach your original image so I can try it. By the way, why even do edge detection? Can't you get the object by simple thresholding?