code: def rfft2d_freqs(h, w):
      """Computes 2D spectrum frequencies."""
  
      fy = np.fft.fftfreq(h)[:, None]
      # when we have an odd input dimension we need to keep one additional
      # frequency and later cut off 1 pixel
      if w % 2 == 1:
          fx = np.fft.fftfreq(w)[: w // 2 + 2]
      else:
          fx = np.fft.fftfreq(w)[: w // 2 + 1]
      return np.sqrt(fx * fx + fy * fy)
  
file_path: lucid/lucid/optvis/param/spatial.py
imports: import warnings
  import numpy
  import tensorflow
  from lucid.optvis.param.lowres import lowres_tensor
label_desc: Use image node_id 2 for calling a global function with example usage: rfft2d_freqs(h, w) and returns: np