code: def iterative_colorization(
      distiller,
      images,
      x,
      ts,
      t_min=0.002,
      t_max=80.0,
      rho=7.0,
      steps=40,
      generator=None,
  ):
      def obtain_orthogonal_matrix():
          vector = np.asarray([0.2989, 0.5870, 0.1140])
          vector = vector / np.linalg.norm(vector)
          matrix = np.eye(3)
          matrix[:, 0] = vector
          matrix = np.linalg.qr(matrix)[0]
          if np.sum(matrix[:, 0]) < 0:
              matrix = -matrix
          return matrix
  
      Q = (
          th.from_numpy(obtain_orthogonal_matrix())
          .to(dist_util.dev())
          .to(th.float32)
      )
      mask = th.zeros(*x.shape[1:], device=dist_util.dev())
      mask[0, ...] = 1.0
  
      def replacement(x0, x1):
          x0 = th.einsum("bchw,cd->bdhw", x0, Q)
          x1 = th.einsum("bchw,cd->bdhw", x1, Q)
  
          x_mix = x0 * mask + x1 * (1.0 - mask)
          x_mix = th.einsum("bdhw,cd->bchw", x_mix, Q)
          return x_mix
  
      t_max_rho = t_max ** (1 / rho)
      t_min_rho = t_min ** (1 / rho)
      s_in = x.new_ones([x.shape[0]])
      images = replacement(images, th.zeros_like(images))
  
      for i in range(len(ts) - 1):
          t = (
              t_max_rho + ts[i] / (steps - 1) * (t_min_rho - t_max_rho)
          ) ** rho
          x0 = distiller(x, t * s_in)
          x0 = th.clamp(x0, -1.0, 1.0)
          x0 = replacement(images, x0)
          next_t = (
              t_max_rho
              + ts[i + 1] / (steps - 1) * (t_min_rho - t_max_rho)
          ) ** rho
          next_t = np.clip(next_t, t_min, t_max)
          x = x0 + generator.randn_like(x) * np.sqrt(
              next_t**2 - t_min**2
          )
  
      return x, images
  
imports: import random
  import numpy
  import torch
  import torch.nn
  import torch.nn.functional
  from piq import LPIPS
  from torchvision.transforms import RandomCrop
  from .None import dist_util
  from .nn import mean_flat, append_dims, append_zero
  from .random_util import get_generator
label_desc: Use image node_id 14 for calling a global function with example usage: iterative_colorization(distiller, images, x, ts, t_min, t_max, rho, steps, generator) and returns: x,  images, matrix, x_mix