| // Ceres Solver - A fast non-linear least squares minimizer |
| // Copyright 2015 Google Inc. All rights reserved. |
| // http://ceres-solver.org/ |
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| // Author: strandmark@google.com (Petter Strandmark) |
| // |
| // Class for loading the data required for descibing a Fields of Experts (FoE) |
| // model. The Fields of Experts regularization consists of terms of the type |
| // |
| // alpha * log(1 + (1/2)*sum(F .* X)^2), |
| // |
| // where F is a d-by-d image patch and alpha is a constant. This is implemented |
| // by a FieldsOfExpertsSum object which represents the dot product between the |
| // image patches and a FieldsOfExpertsLoss which implements the log(1 + (1/2)s) |
| // part. |
| // |
| // [1] S. Roth and M.J. Black. "Fields of Experts." International Journal of |
| // Computer Vision, 82(2):205--229, 2009. |
| |
| #ifndef CERES_EXAMPLES_FIELDS_OF_EXPERTS_H_ |
| #define CERES_EXAMPLES_FIELDS_OF_EXPERTS_H_ |
| |
| #include <iostream> |
| #include <vector> |
| |
| #include "ceres/cost_function.h" |
| #include "ceres/loss_function.h" |
| #include "ceres/sized_cost_function.h" |
| #include "pgm_image.h" |
| |
| namespace ceres { |
| namespace examples { |
| |
| // One sum in the FoE regularizer. This is a dot product between a filter and an |
| // image patch. It simply calculates the dot product between the filter |
| // coefficients given in the constructor and the scalar parameters passed to it. |
| class FieldsOfExpertsCost : public ceres::CostFunction { |
| public: |
| explicit FieldsOfExpertsCost(const std::vector<double>& filter); |
| // The number of scalar parameters passed to Evaluate must equal the number of |
| // filter coefficients passed to the constructor. |
| bool Evaluate(double const* const* parameters, |
| double* residuals, |
| double** jacobians) const override; |
| |
| private: |
| const std::vector<double>& filter_; |
| }; |
| |
| // The loss function used to build the correct regularization. See above. |
| // |
| // f(x) = alpha_i * log(1 + (1/2)s) |
| // |
| class FieldsOfExpertsLoss : public ceres::LossFunction { |
| public: |
| explicit FieldsOfExpertsLoss(double alpha) : alpha_(alpha) {} |
| void Evaluate(double, double*) const override; |
| |
| private: |
| const double alpha_; |
| }; |
| |
| // This class loads a set of filters and coefficients from file. Then the users |
| // obtains the correct loss and cost functions through NewCostFunction and |
| // NewLossFunction. |
| class FieldsOfExperts { |
| public: |
| // Creates an empty object with size() == 0. |
| FieldsOfExperts(); |
| // Attempts to load filters from a file. If unsuccessful it returns false and |
| // sets size() == 0. |
| bool LoadFromFile(const std::string& filename); |
| |
| // Side length of a square filter in this FoE. They are all of the same size. |
| int Size() const { return size_; } |
| |
| // Total number of pixels the filter covers. |
| int NumVariables() const { return size_ * size_; } |
| |
| // Number of filters used by the FoE. |
| int NumFilters() const { return num_filters_; } |
| |
| // Creates a new cost function. The caller is responsible for deallocating the |
| // memory. alpha_index specifies which filter is used in the cost function. |
| ceres::CostFunction* NewCostFunction(int alpha_index) const; |
| // Creates a new loss function. The caller is responsible for deallocating the |
| // memory. alpha_index specifies which filter this loss function is for. |
| ceres::LossFunction* NewLossFunction(int alpha_index) const; |
| |
| // Gets the delta pixel indices for all pixels in a patch. |
| const std::vector<int>& GetXDeltaIndices() const { return x_delta_indices_; } |
| const std::vector<int>& GetYDeltaIndices() const { return y_delta_indices_; } |
| |
| private: |
| // The side length of a square filter. |
| int size_; |
| // The number of different filters used. |
| int num_filters_; |
| // Pixel offsets for all variables. |
| std::vector<int> x_delta_indices_, y_delta_indices_; |
| // The coefficients in front of each term. |
| std::vector<double> alpha_; |
| // The filters used for the dot product with image patches. |
| std::vector<std::vector<double>> filters_; |
| }; |
| |
| } // namespace examples |
| } // namespace ceres |
| |
| #endif // CERES_EXAMPLES_FIELDS_OF_EXPERTS_H_ |