title: How I should create complex number from image data for Fast Fourier Transform (fft, swift)?
body: <p>I have array of grayscale for example <code>[0.0, 0.0, 0.0, 255.0, 255.0, 255.0, 130.0, 130.0, 130.0]</code> 3x3 dimension, I need create array of complex numbers for fft function. <strong>How I should convert this array?</strong> 
  Im using swift 4 and it is for iOS, but I think its no matter. And also using Accelerate framework from Apple</p>
  
  <p>so have 3 questions</p>
  
  <ol>
  <li><strong>How I should convert this array?</strong></li>
  <li><strong>Is there any common theory how do it?</strong></li>
  <li><strong>How should I do it for RGB when working with channels?</strong></li>
  </ol>