Adding a denoising example using Fields of Experts.
We have permission from Stefan Roth to use the coefficients from his
Matlab toolbox. They have been added as *.foe files.
Change-Id: Ice529e5cab0302b9f27648dd3c8e5ed7b9662aba
diff --git a/examples/fields_of_experts.cc b/examples/fields_of_experts.cc
new file mode 100644
index 0000000..0cee40b
--- /dev/null
+++ b/examples/fields_of_experts.cc
@@ -0,0 +1,152 @@
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2012 Google Inc. All rights reserved.
+// http://code.google.com/p/ceres-solver/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+// this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+// this list of conditions and the following disclaimer in the documentation
+// and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+// used to endorse or promote products derived from this software without
+// specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: strandmark@google.com (Petter Strandmark)
+//
+// Class for loading the data required for descibing a Fields of Experts (FoE)
+// model.
+
+#include "fields_of_experts.h"
+
+#include <fstream>
+#include <cmath>
+
+#include "pgm_image.h"
+
+namespace ceres {
+namespace examples {
+
+FieldsOfExpertsCost::FieldsOfExpertsCost(const std::vector<double>& filter)
+ : filter_(filter) {
+ set_num_residuals(1);
+ for (int i = 0; i < filter_.size(); ++i) {
+ mutable_parameter_block_sizes()->push_back(1);
+ }
+}
+
+// This is a dot product between a the scalar parameters and a vector of filter
+// coefficients.
+bool FieldsOfExpertsCost::Evaluate(double const* const* parameters,
+ double* residuals,
+ double** jacobians) const {
+ int num_variables = filter_.size();
+ residuals[0] = 0;
+ for (int i = 0; i < num_variables; ++i) {
+ residuals[0] += filter_[i] * parameters[i][0];
+ }
+
+ if (jacobians != NULL) {
+ for (int i = 0; i < num_variables; ++i) {
+ if (jacobians[i] != NULL) {
+ jacobians[i][0] = filter_[i];
+ }
+ }
+ }
+
+ return true;
+}
+
+// This loss function builds the FoE terms and is equal to
+//
+// f(x) = alpha_i * log(1 + (1/2)s)
+//
+void FieldsOfExpertsLoss::Evaluate(double sq_norm, double rho[3]) const {
+ const double c = 0.5;
+ const double sum = 1.0 + sq_norm * c;
+ const double inv = 1.0 / sum;
+ // 'sum' and 'inv' are always positive, assuming that 's' is.
+ rho[0] = alpha_ * log(sum);
+ rho[1] = alpha_ * c * inv;
+ rho[2] = - alpha_ * c * c * inv * inv;
+}
+
+FieldsOfExperts::FieldsOfExperts()
+ : size_(0), num_filters_(0) {
+}
+
+bool FieldsOfExperts::LoadFromFile(const std::string& filename) {
+ std::ifstream foe_file(filename.c_str());
+ foe_file >> size_;
+ foe_file >> num_filters_;
+ if (size_ < 0 || num_filters_ < 0) {
+ return false;
+ }
+ const int num_variables = NumVariables();
+
+ x_delta_indices_.resize(num_variables);
+ for (int i = 0; i < num_variables; ++i) {
+ foe_file >> x_delta_indices_[i];
+ }
+
+ y_delta_indices_.resize(NumVariables());
+ for (int i = 0; i < num_variables; ++i) {
+ foe_file >> y_delta_indices_[i];
+ }
+
+ alpha_.resize(num_filters_);
+ for (int i = 0; i < num_filters_; ++i) {
+ foe_file >> alpha_[i];
+ }
+
+ filters_.resize(num_filters_);
+ for (int i = 0; i < num_filters_; ++i) {
+ filters_[i].resize(num_variables);
+ for (int j = 0; j < num_variables; ++j) {
+ foe_file >> filters_[i][j];
+ }
+ }
+
+ // If any read failed, return failure.
+ if (!foe_file) {
+ size_ = 0;
+ return false;
+ }
+
+ // There cannot be anything else in the file. Try reading another number and
+ // return failure if that succeeded.
+ double temp;
+ foe_file >> temp;
+ if (foe_file) {
+ size_ = 0;
+ return false;
+ }
+
+ return true;
+}
+
+ceres::CostFunction* FieldsOfExperts::NewCostFunction(int alpha_index) const {
+ return new FieldsOfExpertsCost(filters_[alpha_index]);
+}
+
+ceres::LossFunction* FieldsOfExperts::NewLossFunction(int alpha_index) const {
+ return new FieldsOfExpertsLoss(alpha_[alpha_index]);
+}
+
+
+} // namespace examples
+} // namespace ceres
