Urgent help for Image extraction for object detection using MATLAB

Hello friends, I am working on an object detection project and I am unable to extract small windows from my image. I am using Harris Corner detector to detect corners. The corner_detector() returns C which is a binary image where every detected corner is denoted as 1 or white pixel and rest are black or 0. Using these corners as my central point, I have to extract 4 windows neighbouring it i.e. top-left, top-right, bottom-left, bottom-right windows of certain dimension. Here is the code for it:

function [R] = preSelection (~, SF, ~, fThr, vThr, sThr)

I = imread('C:\Users\verma\Desktop\image1_resized.jpg');
J = I;
C = corner_detector(J);
%figure, imshow(I)
%figure, imshow(C)
[m,n] = size(C);
t = [0.5,1,2,3,5];
for i=1:m
    for j=1:n
        for k=1:size(t)
            m1 = t(k) * 150;
            n1 = t(k) * 250;
            Win1 = rand(m1,n1);
            Win2 = rand(m1,n1);
            Win3 = rand(m1,n1);
            Win4 = rand(m1,n1);
            if C(i,j) == 1
                if (i>m1 && j>n1)
                    for a=1:m1
                        for b=1:n1
                            Win1(a,b,1) = I(i-m1,j-n1,1);
                            Win1(a,b,2) = I(i-m1,j-n1,2);
                            Win1(a,b,3) = I(i-m1,j-n1,3);
                            %Win2 = imcrop(I, [ i (j-n1) m1 n1]);
                            %Win3 = imcrop(I, [(i-m1) j m1 n1]);
                            %Win4 = imcrop(I, [ i j m1 n1]);
                        end
                    end
                end
            end
            figure, imshow(Win1)
            %figure, imshow(Win2)
            %figure, imshow(Win3)
            %figure, imshow(Win4)

          end
      end
  end

return

Here t is an array which contains some values according to which the selection window will scale itself. It is nothing but a scaling factor. Now the 4 windows are created of a certain dimension and then from I (original image) the pixel values are read and stored in it. I am supposed to generate an output like this (see 3.png). However, no matter what code I write, I always get this as the output (see 4.png). I have also used imcrop also but to no avail (hence, commented out).

What am I doing wrong? What should I do to correct it?

Sample image on which I am testing my code (see image1_resized.jpg).