changing a matrix size

Hello,

Basically i want to change a logical matrix size from 144x144 to 512x512, here is the case that i have:

i have two images of the same object with those sizes accordingly with some region of interest approximately in the middle of the 144 image here is a small example:

the matrix of the region is as follows:

[0000000000

0001111000

0000110000

0000000000]

the regions are hazardous but in the middle give or take, i have them all. now i want to apply those regions to the bigger image so i need to expande the matrix to go with the 512x512 image. as follows

[000000000000000000000

000000111111110000000

000000001111000000000

000000000000000000000]

any ideas ?

Regards

[Steven Lord]

If 512 was an integer multiple of 144 I would suggest repelem but it's not. So I think we're going to need to know more about what you intend "expande[sic] the matrix" to mean in this context to be able to offer useful suggestions. Let's take a smaller concrete example.

smallPattern = [0 0 0 1; 0 1 1 0; 0 0 1 0; 1 0 0 0]

If you wanted to expand smallPattern from a 4-by-4 matrix to a 10-by-10 matrix named largePattern, what exactly would largePattern contain and why? Please be as specific as possible.

[abdelillah douhi]

Hi steven,

so this is my reagion on a 144x144 image, and the matrix of the region is 144x144 matrix too, this inner space of the region is ones the exteriour is zeros, i want to aplly the region to a larger image so i need to scale the region matrix to go with the 512x512 image. I hope you do get the idea now

Ps the region should be scaled too as the images are for the same patient

Regards

[Bruno Luong]

What you plot are not logical matrix.

[Steven Lord]

I hope you do get the idea now

No, I don't. There are many different ways you could expand a 144-by-144 matrix to be a 512-by-512 matrix. I asked what method you want to use. To make this a bit more concrete, using my 4-by-4 example above:

smallPattern = [0 0 0 1; 0 1 1 0; 0 0 1 0; 1 0 0 0]

Should it be expanded to 10-by-10 by padding?

larger = zeros(10);
% Pad along the bottom and right
largePattern1 = larger; largePattern1(1:4, 1:4) = smallPattern
% Pad along the top and right
largePattern2 = larger; largePattern2(7:10, 1:4) = smallPattern
% Pad on all four sides
largePattern3 = larger; largePattern3(4:7, 4:7) = smallPattern

Should we replicate the rows and columns?

% Each element is roughly equal in size, extra rows go to the
% left and top sections
largePattern4 = repelem(smallPattern, [3 2 3 2], [3 2 3 2])
% Shows some symmetry
largePattern5 = repelem(smallPattern, [2 3 3 2], [3 2 2 3])

Should we replicate the matrix as a whole then trim off the extra pieces?

twelve = repmat(smallPattern, 3);
% Trim the bottom and right
largePattern6 = twelve(1:10, 1:10)
% Trim the border on all four sides
largePattern7 = twelve(2:11, 2:11)
% Trim the top and left
largePattern8 = twelve(3:12, 3:12)

Each of those eight larger patterns is a different matrix, built in some way from the small pattern, and all are 10-by-10.

Answer 1

[Bruno Luong]

% A is 144 x 144 input binary matrix
I512 = logical(interp2(...
             linspace(0,1,size(A,2)),...
             linspace(0,1,size(A,1)),...
             double(A),...
             linspace(0,1,512),...
             linspace(0,1,512)')); % this is the "same" image with size 512 x 512

[abdelillah douhi]

thanks for your answer but in fact the matrix of the roi ( the cercle) is logical, or else my program wont work, i tryed your solution it did solve the problem on the image but the outcom of the program didn't give exactly the values that i wanted didn't give any actualy.

[abdelillah douhi]

thank you very much