How can i use interp1 to enlarge the photo 'lena'

I have a image which is lena_half, 256*256*3, how can I use interp1 to enlarge it?

What I have done so far, but not working: %%

lena = double(imread('lena.tif'));
figure(6);
imshow(lena)
y_LenaHalf = double(imread('lena_half.tif'));
figure(7);
imshow(y_LenaHalf)
x2 = 1:256;
xi_2 = 1:(255/511):256;
yi_2 = interp1(x2, y_LenaHalf, xi_2);
yi2_2 = interp1(x2, yi_2.', xi_2).';
yii_2 = interp1(yi2_2, yi2.', xi_2);
figure(8);
imshow(uint8(yii_2))
SE2 = (lena - yii_2).^2;
MSE2 = mean(mean(SE2));

Also, there is an error: Error using .' Transpose on ND array is not defined. Use PERMUTE instead.

Answer 1

[KSSV]

Check this link for the same question: https://in.mathworks.com/matlabcentral/answers/399622-resizing-images-using-interp1

[Dingbang Liang]

What do i need to change if i want to enlarge a size of lena 256*256*3 to 512*512*3?

[KSSV]

Have a look on code, thre is a variable N. You need to change that.

[Dingbang Liang]

Yeah, but only for the width, not the length, what to change to extend the length?

[KSSV]

I already mentioned there...it does interpolation along one dimension..you need to run another loop along column.....also...

[Image Analyst]

Why? What are you not simply using imresize()? Why do it the hard way? Is it your homework that's forcing you to do it the least convenient way?