merge two binary images using Matlab

Question

I need to create two different black binary rectangles using Matlab, to overlay a part of both and to extract the insertion.

How can I overlay two binary images?

-------|----------|
|      |     2    |
|    1 |----|-----|
|           |
|-----------|

I created my two binary images using the false(X, Y) Matlab function.

I dont find how to produce the merge the two images and to extract the insertion.

Answer 1

Make a background matrix that can contain both rectangles before you translate them, and assign values of the background matrix to the areas where your rectangles will be. This way you have two matrices of the same size, on which you can do logical or arithmetic operations. If you use different values for each rectangle and the background, things like sums will show up in different colors. Here's a text version that demonstrates:

octave:11> bga = bgb = ones(10,10)
bga =

   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1

octave:12> bgb
bgb =

   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1

octave:13> a=false(3,4)
a =

   0   0   0   0
   0   0   0   0
   0   0   0   0

octave:14> b=false(5,5)
b =

   0   0   0   0   0
   0   0   0   0   0
   0   0   0   0   0
   0   0   0   0   0
   0   0   0   0   0

octave:15> bga(3:5,4:7) = a
bga =

   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   0   0   0   0   1   1   1
   1   1   1   0   0   0   0   1   1   1
   1   1   1   0   0   0   0   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1

octave:16> bgb(1:5,1:5) = b
bgb =

   0   0   0   0   0   1   1   1   1   1
   0   0   0   0   0   1   1   1   1   1
   0   0   0   0   0   1   1   1   1   1
   0   0   0   0   0   1   1   1   1   1
   0   0   0   0   0   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1

octave:17> bga | bgb
ans =

   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   0   0   1   1   1   1   1
   1   1   1   0   0   1   1   1   1   1
   1   1   1   0   0   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1
   1   1   1   1   1   1   1   1   1   1