How to find the intersection of the diagonals of a bounding box?

I need to find the intersection of the diagonals of the of the bounding box, i also need to find the co-ordinates of the same. This is the code I'm using. I need it find out the centre of the ROI, that being hand in my case.

clear all;

close all;

clc;

%intitial setup to acquire image

vid = videoinput('winvideo', 1, 'YUY2_640x480');

%set the FPT to infinity

set(vid, 'FramesPerTrigger', Inf);

%set colour space to RGB

set(vid, 'ReturnedColorspace', 'rgb');

%set frame grab interval as 5

vid.FrameGrabInterval = 5;

%start the acquisation

start(vid);

while(vid.FramesAcquired<=100);

    %get the snapshot of the frame

    data= getsnapshot(vid);

    %subtract gray from individual component

    diff_im = imsubtract(data(:,:,1), rgb2gray(data));

    %median filtering, each pixel contains median value in the 3 by 3 nhbd

    %around the corresponding pixel in the input

    diff_im = medfilt2(diff_im, [3,3]);

    %adjust image intensity values of colourmap

    diff_im = imadjust(diff_im);

    %compute global threshold level used to convert bin image

    level = graythresh(diff_im);

    %convert to binary image

    bw = im2bw(diff_im,level);

    %fill holes

    bw5 = imfill (bw, 'holes');

    %contains labels for the connected objects in BW

    bw6 = bwlabel(bw5, 8);

    %compute area centroid and boundingbox

    stats = regionprops(bw6, ['basic']);

    s = regionprops(bw6, 'centroid');

    [N,M] = size(stats);

    if (bw==0)

        break;

    else

        tmp = stats(1);

    for i = 2 : N

        if stats(i).Area > tmp.Area

            tmp = stats(i);

        end

    end

    bb = tmp.BoundingBox;

    bc = tmp.Centroid;

    imshow(data)

    hold on

    rectangle('Position', bb, 'EdgeColor', 'r', 'LineWidth', 2)

    for z= 1:numel(s)

        plot(s(z).Centroid(1), s(z).Centroid(2), 'ro');

    end

    hold off

    end

end

stop(vid);

flushdata(vid);

Answer 1

[Image Analyst]

Bounding boxes always always align with the image edges, so the center and where the diagonals intersect will always simply be the average of the x and y coordinates.

[Suhas Yelluru]

the values of the x and y coordinates of the bounding box keeps changing as this is an effort to track the hand in real time, how do I average the coordinates in this case?

Sorry for being ignorant, Still learning. thanks!

[Image Analyst]

xMiddle = (xLeft + xRight) / 2;
yMiddle = (yTop + yBottom) / 2;

xLeft, etc. are the bounding box coordinates, which may change at each frame but you're getting them from the .Boundingbox property of your regionprops() output.

[DGM]

If you're dealing with a boundingbox from regionprops or something:

S = regionprops(inpict,'boundingbox');
bbox = S.BoundingBox; 
boxcenter = bbox(1:2) + bbox(3:4)/2 % [x y]