Discrete Fourier transformation

Question

gauss=exp(-(x.^2+y.^2)/scale(i)^2);

gaus=gauss/sum(gauss(:));
x=fft2(gaus,size(image,1),size(image,2));

I want to ask about this part of codein MATLAB

1. What is the meaning of colon here (gauss(:))
2. I want to implement the Discrete Fourier transformation in ( x)
   by MAY OWN FUNCTION,Can I apply DFT to every three component independently and then add the result together?

Answer 1

1) The colon operator reshapes the matrix into a vector.

2) You can transform each sample separately.