How to map two different gray pattern in two images?

I have two images temp1.jpg and temp2.jpg. Both images have some large gray collor pattern. I want to make boundary around each pattern and map pattern in temp1 with patten in temp2

[Anu Gupta]

I know how to use bwconncomp to find out different connected patterns in a image. But dont know how to make boundary around it and map it with other same kind of image.

Answer 1

[KSSV]

You can make boundary as below:

I = imread('temp1.jpg') ; 
[nx,ny,nz] = size(I) ; 
[X,Y] = meshgrid(1:ny,1:nx) ; 
id = I~=255 ;
x = X(id) ; y = Y(id) ; 
idx = boundary(x,y) ; 

imshow(I)
hold on
plot(x(idx),y(idx),'r') 

[Anu Gupta]

Thank you KSSV for your reply.

I used the code you shared but it includes all the patterns inside the boundary. Also, the pattern is not closed around the shape. However, I want a closed shape around Large pattern only. Also, I want to note the position of these patterns in each image.

[KSSV]

You have positions in your hand already.....(x,y) are the positions.