how to create bouding box

I have centroid of picture I want create bounding box upper and lower from center point of picture

Answer 1

[Image Analyst]

Use rectangle() and your x and y centroid which you say you already have:

[rows, columns, numberOfColorChannels] = size(mask);
imshow(mask);
axis on;
hold on
% Specify half height of the rectangle.
halfHeight = 200;  % Whatever you want.
% Plot rectangle in upper half.
rectangle('Position',[1, yCentroid - halfHeight, columns, 2*halfHeight], ...
  'LineWidth', 3, 'EdgeColor', 'b');
% Plot star in middle
plot(xCentroid, yCentroid, 'b*', 'MarkerSize', 30)
hold off