fft_real_imaginary.js

/*
 * Calc Real and Imaginary Parts of a FFT
 * Jean-Christophe Taveau
 * 2022/07/20
 */
 
const imp = IJ.getImage();
const w = imp.getWidth();
const h = imp.getHeight();
// Create Output
const re = new FloatProcessor(w,h);
const im = new FloatProcessor(w,h);

// Calc Real and Imaginary Parts
const mag = imp.getImageStack().getProcessor(1);
const phase = imp.getImageStack().getProcessor(2);

for (let i = 0; i < w*h;i++) {
  const rei = mag.getf(i) * Math.cos(phase.getf(i) );
  const imi = mag.getf(i) * Math.sin(phase.getf(i) );
  re.setf(i,rei);
  im.setf(i,imi);
}

const stack = new ImageStack();
stack.addSlice("Real",re);
stack.addSlice("Imaginary",im);
const output = new ImagePlus("Complex of Signal",stack);
output.show();