MATLAB: I have three image parts and i want to add them and get three images back,but i getting an error due to sizes of matrix is different

Question

clc;
clear all;
I=imread('thumb.jpg');
figure, imshow(I);
[r c]=size(I);
imshow(I); 
for i=1:1:r
    for j=1:1:c
        if I(i,j) > 127
            I1(i,j)=255;
        else
            I1(i,j)=0;
        end  
    end
end
figure, imshow(I1);
I2=I1(1:56, 1:122);
I3=I1(57:113, 1:122);
I4=I1(114:170, 1:122);
figure, imshow(I2);
figure, imshow(I3);
figure, imshow(I4);
Ip=[I1, I2, I3];
imshow(Ip);

Answer 1

Ip=[I1;I2; I3];
imshow(Ip);