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/*
* Copyright (c) 2017-2019 ARM Limited.
*
* SPDX-License-Identifier: MIT
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "HOGDescriptor.h"
#include "Derivative.h"
#include "Magnitude.h"
#include "Phase.h"
namespace arm_compute
{
namespace test
{
namespace validation
{
namespace reference
{
namespace
{
template <typename T>
void hog_orientation_compute(const SimpleTensor<T> &mag, const SimpleTensor<T> &phase, std::vector<T> &bins, const HOGInfo &hog_info)
{
const Size2D &cell_size = hog_info.cell_size();
const size_t num_bins = hog_info.num_bins();
float phase_scale = (PhaseType::SIGNED == hog_info.phase_type() ? num_bins / 360.0f : num_bins / 180.0f);
phase_scale *= (PhaseType::SIGNED == hog_info.phase_type() ? 360.0f / 255.0f : 1.0f);
int row_idx = 0;
for(size_t yc = 0; yc < cell_size.height; ++yc)
{
for(size_t xc = 0; xc < cell_size.width; xc++)
{
const float mag_value = mag[(row_idx + xc)];
const float phase_value = phase[(row_idx + xc)] * phase_scale + 0.5f;
const float w1 = phase_value - floor(phase_value);
// The quantised phase is the histogram index [0, num_bins - 1]
// Check limit of histogram index. If hidx == num_bins, hidx = 0
const auto hidx = static_cast<unsigned int>(phase_value) % num_bins;
// Weighted vote between 2 bins
bins[hidx] += mag_value * (1.0f - w1);
bins[(hidx + 1) % num_bins] += mag_value * w1;
}
row_idx += cell_size.width;
}
}
template <typename T>
void hog_block_normalization_compute(SimpleTensor<T> &block, SimpleTensor<T> &desc, const HOGInfo &hog_info, uint32_t block_idx)
{
const int num_bins_per_block = desc.num_channels();
const HOGNormType norm_type = hog_info.normalization_type();
const Coordinates id = index2coord(desc.shape(), block_idx);
float sum = 0.0f;
// Calculate sum
for(int i = 0; i < num_bins_per_block; ++i)
{
const float val = block[i];
sum += (norm_type == HOGNormType::L1_NORM) ? std::fabs(val) : val * val;
}
// Calculate normalization scale
float scale = 1.0f / (std::sqrt(sum) + num_bins_per_block * 0.1f);
if(norm_type == HOGNormType::L2HYS_NORM)
{
// Reset sum
sum = 0.0f;
for(int i = 0; i < num_bins_per_block; ++i)
{
float val = block[i] * scale;
// Clip scaled input_value if over l2_hyst_threshold
val = fmin(val, hog_info.l2_hyst_threshold());
sum += val * val;
block[i] = val;
}
// We use the same constants of OpenCV
scale = 1.0f / (std::sqrt(sum) + 1e-3f);
}
for(int i = 0; i < num_bins_per_block; ++i)
{
block[i] *= scale;
reinterpret_cast<float *>(desc(id))[i] = block[i];
}
}
} // namespace
template <typename T, typename U, typename V>
void hog_orientation_binning(const SimpleTensor<T> &mag, const SimpleTensor<U> &phase, SimpleTensor<V> &hog_space, const HOGInfo &hog_info)
{
const Size2D &cell_size = hog_info.cell_size();
const size_t num_bins = hog_info.num_bins();
const size_t shape_width = hog_space.shape().x() * hog_info.cell_size().width;
const size_t shape_height = hog_space.shape().y() * hog_info.cell_size().height;
TensorShape cell_shape(cell_size.width, cell_size.height);
SimpleTensor<V> mag_cell(cell_shape, DataType::F32);
SimpleTensor<V> phase_cell(cell_shape, DataType::F32);
int cell_idx = 0;
int y_offset = 0;
// Traverse shape
for(auto sy = cell_size.height; sy <= shape_height; sy += cell_size.height)
{
int x_offset = 0;
for(auto sx = cell_size.width; sx <= shape_width; sx += cell_size.width)
{
int row_idx = 0;
int elem_idx = 0;
// Traverse cell
for(auto y = 0u; y < cell_size.height; ++y)
{
for(auto x = 0u; x < cell_size.width; ++x)
{
int shape_idx = x + row_idx + x_offset + y_offset;
mag_cell[elem_idx] = mag[shape_idx];
phase_cell[elem_idx] = phase[shape_idx];
elem_idx++;
}
row_idx += shape_width;
}
// Partition magnitude values into bins based on phase values
std::vector<V> bins(num_bins);
hog_orientation_compute(mag_cell, phase_cell, bins, hog_info);
for(size_t i = 0; i < num_bins; ++i)
{
hog_space[cell_idx * num_bins + i] = bins[i];
}
x_offset += cell_size.width;
cell_idx++;
}
y_offset += (cell_size.height * shape_width);
}
}
template <typename T>
void hog_block_normalization(SimpleTensor<T> &desc, const SimpleTensor<T> &hog_space, const HOGInfo &hog_info)
{
const Size2D cells_per_block = hog_info.num_cells_per_block();
const Size2D cells_per_block_stride = hog_info.num_cells_per_block_stride();
const Size2D &block_size = hog_info.block_size();
const Size2D &block_stride = hog_info.block_stride();
const size_t num_bins = hog_info.num_bins();
const size_t shape_width = hog_space.shape().x() * hog_info.cell_size().width;
const size_t shape_height = hog_space.shape().y() * hog_info.cell_size().height;
const size_t num_bins_per_block_x = cells_per_block.width * num_bins;
// Tensor representing single block
SimpleTensor<T> block(TensorShape{ 1u, 1u }, DataType::F32, cells_per_block.area() * num_bins);
uint32_t block_idx = 0;
int block_y_offset = 0;
// Traverse shape
for(auto sy = block_size.height; sy <= shape_height; sy += block_stride.height)
{
int block_x_offset = 0;
for(auto sx = block_size.width; sx <= shape_width; sx += block_stride.width)
{
int cell_y_offset = 0;
int elem_idx = 0;
// Traverse block
for(auto y = 0u; y < cells_per_block.height; ++y)
{
for(auto x = 0u; x < num_bins_per_block_x; ++x)
{
int idx = x + cell_y_offset + block_x_offset + block_y_offset;
block[elem_idx] = hog_space[idx];
elem_idx++;
}
cell_y_offset += hog_space.shape().x() * num_bins;
}
// Normalize block and write to descriptor
hog_block_normalization_compute(block, desc, hog_info, block_idx);
block_x_offset += cells_per_block_stride.width * num_bins;
block_idx++;
}
block_y_offset += cells_per_block_stride.height * num_bins * hog_space.shape().x();
}
}
template <typename T, typename U>
SimpleTensor<T> hog_descriptor(const SimpleTensor<U> &src, BorderMode border_mode, U constant_border_value, const HOGInfo &hog_info)
{
SimpleTensor<int16_t> grad_x;
SimpleTensor<int16_t> grad_y;
// Create tensor info for HOG descriptor
TensorInfo desc_info(hog_info, src.shape().x(), src.shape().y());
SimpleTensor<T> desc(desc_info.tensor_shape(), DataType::F32, desc_info.num_channels());
// Create HOG space tensor (num_cells_x, num_cells_y)
TensorShape hog_space_shape(src.shape().x() / hog_info.cell_size().width,
src.shape().y() / hog_info.cell_size().height);
// For each cell a histogram with a num_bins is created
TensorInfo info_hog_space(hog_space_shape, hog_info.num_bins(), DataType::F32);
SimpleTensor<T> hog_space(info_hog_space.tensor_shape(), DataType::F32, info_hog_space.num_channels());
// Calculate derivative
std::tie(grad_x, grad_y) = derivative<int16_t>(src, border_mode, constant_border_value, GradientDimension::GRAD_XY);
// For each cell create histogram based on magnitude and phase
hog_orientation_binning(magnitude(grad_x, grad_y, MagnitudeType::L2NORM),
phase(grad_x, grad_y, hog_info.phase_type()),
hog_space,
hog_info);
// Normalize histograms based on block size
hog_block_normalization(desc, hog_space, hog_info);
return desc;
}
template void hog_orientation_binning(const SimpleTensor<int16_t> &mag, const SimpleTensor<uint8_t> &phase, SimpleTensor<float> &hog_space, const HOGInfo &hog_info);
template void hog_block_normalization(SimpleTensor<float> &desc, const SimpleTensor<float> &hog_space, const HOGInfo &hog_info);
template SimpleTensor<float> hog_descriptor(const SimpleTensor<uint8_t> &src, BorderMode border_mode, uint8_t constant_border_value, const HOGInfo &hog_info);
} // namespace reference
} // namespace validation
} // namespace test
} // namespace arm_compute