I wonder what the purpose of this is, but here goes:
Image1 = imread('rice.png');
Image2 = uint8(zeros(8,8));
Image3 = Image1; Image3(1:8,1:8) = Image2;
You could add the bounding box, if that's what you mean, by manually adding rows and columns of black pixels around your Image2. Image2(1,:) = ones(size(Image2(1,:))); and so on for all the borders. Does this work?