Scale Image by using FFT
Yes image scaling can also be performed in frequency domain using DFT/FFT.

For example, given an $N \times M$ image, you can implement the interpolation by integer $K$ in the frequency domain by enlarging the $N \times M$ point DFT/FFT of the original image into $K \cdot N \times K \cdot M$ size where new DFT/FFT samples are all zero; except at the four corners; effectiveley you are zero padding the original DFT/FFT in frequency domain. The effect in time domain wil be interpolation.

The following is an example of 2x image zooming using FFT.

K = 2;
I = im2double(imread('Cameraman.tif');
S = size(I);

F = fft2(I);
F2 = repmat( K*K*F , K , K);

Mask = zeros(K*S);
Mask(1:S(1)/2+1 , 1:S(2)/2+1) = 1;
Mask(end-S(1)/2 : end , 1:S(2)/2+1) = 1;
Mask(1:S(1)/2+1 , end-S(2)/2 :end ) = 1;
Mask(end-S(1)/2 : end , end-S(2)/2 :end ) = 1;

F2 = Mask.*F2;

I2 = real( ifft2( F2 ));
figure,imshow(I);title('Original');
figure,ishow(I2);title('2x Zoomed');


You should adjust the mask carefully for even and odd length dimensions...