maxpool.h

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// File:        maxpool.h
// Description: Standard Max-Pooling layer.
// Author:      Ray Smith
// Created:     Tue Mar 18 16:28:18 PST 2014
//
// (C) Copyright 2014, Google Inc.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#ifndef TESSERACT_LSTM_MAXPOOL_H_
#define TESSERACT_LSTM_MAXPOOL_H_
 
#include "reconfig.h"
 
namespace tesseract {
 
// Maxpooling reduction. Independently for each input, selects the location
// in the rectangle that contains the max value.
// Backprop propagates only to the position that was the max.
class Maxpool : public Reconfig {
public:
  TESS_API
  Maxpool(const char *name, int ni, int x_scale, int y_scale);
  ~Maxpool() override = default;
 
  // Accessors.
  std::string spec() const override {
    return "Mp" + std::to_string(y_scale_) + "," + std::to_string(x_scale_);
  }
 
  // Reads from the given file. Returns false in case of error.
  bool DeSerialize(TFile *fp) override;
 
  // Runs forward propagation of activations on the input line.
  // See Network for a detailed discussion of the arguments.
  void Forward(bool debug, const NetworkIO &input, const TransposedArray *input_transpose,
               NetworkScratch *scratch, NetworkIO *output) override;
 
  // Runs backward propagation of errors on the deltas line.
  // See Network for a detailed discussion of the arguments.
  bool Backward(bool debug, const NetworkIO &fwd_deltas, NetworkScratch *scratch,
                NetworkIO *back_deltas) override;
 
private:
  // Memory of which input was the max.
  GENERIC_2D_ARRAY<int> maxes_;
};
 
} // namespace tesseract.
 
#endif // TESSERACT_LSTM_MAXPOOL_H_