class_docstr: Base class for problems with images.
class_docstr_tok: ["Base","class","for","problems","with","images","."]
docstr: Number of color channels.
docstr_tok: ["Number","of","color","channels","."]
code: def num_channels(self):
      """Number of color channels."""
      return 3
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import io
  import os
  import numpy
  from tensor2tensor.data_generators import generator_utils
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import text_encoder
  from tensor2tensor.layers import common_layers
  from tensor2tensor.layers import modalities
  from tensor2tensor.utils import contrib
  from tensor2tensor.utils import metrics
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling the ImageProblem obj's underlying member method code with example usage: obj.num_channels() and returns: int