tesseract  5.0.0
reversed.h
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1 // File: reversed.h
3 // Description: Runs a single network on time-reversed input, reversing output.
4 // Author: Ray Smith
5 //
6 // (C) Copyright 2013, Google Inc.
7 // Licensed under the Apache License, Version 2.0 (the "License");
8 // you may not use this file except in compliance with the License.
9 // You may obtain a copy of the License at
10 // http://www.apache.org/licenses/LICENSE-2.0
11 // Unless required by applicable law or agreed to in writing, software
12 // distributed under the License is distributed on an "AS IS" BASIS,
13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 // See the License for the specific language governing permissions and
15 // limitations under the License.
17 
18 #ifndef TESSERACT_LSTM_REVERSED_H_
19 #define TESSERACT_LSTM_REVERSED_H_
20 
21 #include "matrix.h"
22 #include "plumbing.h"
23 
24 namespace tesseract {
25 
26 // C++ Implementation of the Reversed class from lstm.py.
27 class Reversed : public Plumbing {
28 public:
29  TESS_API
30  explicit Reversed(const std::string &name, NetworkType type);
31  ~Reversed() override = default;
32 
33  // Returns the shape output from the network given an input shape (which may
34  // be partially unknown ie zero).
35  StaticShape OutputShape(const StaticShape &input_shape) const override;
36 
37  std::string spec() const override {
38  std::string spec(type_ == NT_XREVERSED ? "Rx" : (type_ == NT_YREVERSED ? "Ry" : "Txy"));
39  // For most simple cases, we will output Rx<net> or Ry<net> where <net> is
40  // the network in stack_[0], but in the special case that <net> is an
41  // LSTM, we will just output the LSTM's spec modified to take the reversal
42  // into account. This is because when the user specified Lfy64, we actually
43  // generated TxyLfx64, and if the user specified Lrx64 we actually
44  // generated RxLfx64, and we want to display what the user asked for.
45  std::string net_spec(stack_[0]->spec());
46  if (net_spec[0] == 'L') {
47  // Setup a from and to character according to the type of the reversal
48  // such that the LSTM spec gets modified to the spec that the user
49  // asked for
50  char from = 'f';
51  char to = 'r';
52  if (type_ == NT_XYTRANSPOSE) {
53  from = 'x';
54  to = 'y';
55  }
56  // Change the from char to the to char.
57  for (auto &it : net_spec) {
58  if (it == from) {
59  it = to;
60  }
61  }
62  spec += net_spec;
63  return spec;
64  }
65  spec += net_spec;
66  return spec;
67  }
68 
69  // Takes ownership of the given network to make it the reversed one.
70  TESS_API
71  void SetNetwork(Network *network);
72 
73  // Runs forward propagation of activations on the input line.
74  // See Network for a detailed discussion of the arguments.
75  void Forward(bool debug, const NetworkIO &input, const TransposedArray *input_transpose,
76  NetworkScratch *scratch, NetworkIO *output) override;
77 
78  // Runs backward propagation of errors on the deltas line.
79  // See Network for a detailed discussion of the arguments.
80  bool Backward(bool debug, const NetworkIO &fwd_deltas, NetworkScratch *scratch,
81  NetworkIO *back_deltas) override;
82 
83 private:
84  // Copies src to *dest with the reversal according to type_.
85  void ReverseData(const NetworkIO &src, NetworkIO *dest) const;
86 };
87 
88 } // namespace tesseract.
89 
90 #endif // TESSERACT_LSTM_REVERSED_H_
NetworkType
Definition: network.h:41
@ NT_XREVERSED
Definition: network.h:54
@ NT_YREVERSED
Definition: network.h:55
@ NT_XYTRANSPOSE
Definition: network.h:56
NetworkType type_
Definition: network.h:300
const std::string & name() const
Definition: network.h:140
NetworkType type() const
Definition: network.h:110
std::vector< Network * > stack_
Definition: plumbing.h:150
void Forward(bool debug, const NetworkIO &input, const TransposedArray *input_transpose, NetworkScratch *scratch, NetworkIO *output) override
Definition: reversed.cpp:52
TESS_API Reversed(const std::string &name, NetworkType type)
Definition: reversed.cpp:26
~Reversed() override=default
TESS_API void SetNetwork(Network *network)
Definition: reversed.cpp:45
StaticShape OutputShape(const StaticShape &input_shape) const override
Definition: reversed.cpp:32
bool Backward(bool debug, const NetworkIO &fwd_deltas, NetworkScratch *scratch, NetworkIO *back_deltas) override
Definition: reversed.cpp:63
std::string spec() const override
Definition: reversed.h:37
#define TESS_API
Definition: export.h:34