MATLAB: Changing image size with interp1()

image processing

I am new to MATLAB so I am unfamiliar with many things. One of the tasks that was handed to me to complete was to change the size of the image using interp1(), I have previously asked the similar question and I am able to change my image size from 256×256 to 256×512. I have only succeeded in changing the image size for rows with the following codes:
data1 = imread('lighthouse_half.png');
 %lighthouse_half 
numcr = 512;
[m,n,p] = size(data1);
iwant = zeros(m,numcr,p);
xi = linspace(1,n,numcr);
for i = 1:m
    for j = 1:p
        T = interp1(1:n,double(data1(i,:,j)),xi);
        iwant(i,:,j) = T;
    end
end
iwant = uint8(iwant);
imshow(iwant);
I have been trying to figure how to change both rows and columns so that I get the image size of 512×512, can someone please help?

Best Answer

data1 = imread('lighthouse_half.png');
 %lighthouse_half 
numcr = 512; numrr = 512 ;
[m,n,p] = size(data1);
% interpolation along column
iwant1 = zeros(m,numcr,p);
xi = linspace(1,n,numcr);
for i = 1:m
    for j = 1:p
        T = interp1(1:n,double(data1(i,:,j)),xi);
        iwant1(i,:,j) = T;        
    end
end
[m,n,p] = size(iwant1);
% interpolation along row
iwant2 = zeros(numrr,numcr,p) ;
yi = linspace(1,m,numrr);
for i = 1:n
    for j = 1:p
        T = interp1(1:m,double(iwant1(:,i,j)),yi);
        iwant2(:,i,j) = T;        
    end
end
iwant2 = uint8(iwant2);
imshow(iwant2);
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