CODEWITHSUNDEEP
matlabimage-processingcombinations
User1772
User1772

Reputation: 91

How do I combining two or more images in Matlab?

I need to combine several images (of different textures) together. I have tried the following code:

% Read 4d data
I1 = importdata('Img1.tif');    
I2 = importdata('Img2.tif');

% Extract a slice of the data
extractImg1 = I1(:,:,1); 
extractImg2 = I2(:,:,1); 

% compute image size
[ny1, nx1] = size(extractA1);
[ny2, nx2] = size(extractA2);

P1 = extractImg1 (round(ny1/2)-120:round(ny1/2)+120, round(nx1/2)-120:round(nx1/2)+120);
figure, imshow(P1); title('Img1');
P2 = extractImg2 (round(ny2/2)-120:round(ny2/2)+120, round(nx2/2)-120:round(nx2/2)+120);
figure, imshow(P2); title('Img2');

Please, what should I do next?

Secondly, the combined image will be needed for laser printing. The images do not have exactly the same pixel dimensions thus; I was told that it would not make sense to combine them, as this might slightly reduce accuracy.

Nonetheless, I still have a feeling that combining the images wouldn’t be wrong considering that they all have the same resolutions.

I need advice as to whether I should go ahead with the combination. Many thanks in advance.

Upvotes: 1

Views: 667

Answers (1)

Cris Luengo
Cris Luengo

Reputation: 60444

You have extracted two equal-sized regions from the two images. If you want to put those side-by-side in the same image, use cat, or equivalently, use the square brackets []:

next_to_each_other = [P1,P2];
on_top_of_each_other = [P1;P2];

But note that you can put these things together even if they don't have the same sizes. For example, if I1 is NxM pixels, and I2 is NxK (with N the vertical size as customary in MATLAB) then you can still do [I1,I2] because the vertical size matches.

If nether the vertical nor horizontal sizes match, you can pad one with zeros (or whatever value is appropriate) using padarray before putting them together:

ny1 = size(I1,1);
ny2 = size(I2,1);
if ny1<ny2
   I1 = padarray(I1,[ny2-ny1,0,0],0,'post'); % The 0 is the value to pad
elseif ny2<ny1
   I2 = padarray(I2,[ny1-ny2,0,0],0,'post'); % The 0 is the value to pad
end
out = [I1,I2];

padarray also allows replicating the data in the matrix instead of padding with zeros. Read the documentation to find what is appropriate. padarray requires the Image Processing Toolbox. If you don't have it, you can replicate its functionality by creating an array with zeros of the appropriate size using the zeros function, and adding it to the image using something like [I1;zeros(ny2-ny1,size(I1,2),size(I1,3)].

Upvotes: 1

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