tf.keras.backend.ctc_decode

tf.keras.backend.ctc_decode(
    y_pred,
    input_length,
    greedy=True,
    beam_width=100,
    top_paths=1
)

Defined in tensorflow/python/keras/_impl/keras/backend.py.

Decodes the output of a softmax.

Can use either greedy search (also known as best path) or a constrained dictionary search.

Arguments:

  • y_pred: tensor (samples, time_steps, num_categories) containing the prediction, or output of the softmax.
  • input_length: tensor (samples, ) containing the sequence length for each batch item in y_pred.
  • greedy: perform much faster best-path search if true. This does not use a dictionary.
  • beam_width: if greedy is false: a beam search decoder will be used with a beam of this width.
  • top_paths: if greedy is false, how many of the most probable paths will be returned.

Returns:

  • Tuple: List: if greedy is true, returns a list of one element that contains the decoded sequence. If false, returns the top_paths most probable decoded sequences. Important: blank labels are returned as -1. Tensor (top_paths, ) that contains the log probability of each decoded sequence.