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/*
* Copyright (c) 2016-2020 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 "arm_compute/runtime/CL/functions/CLEqualizeHistogram.h"
#include "arm_compute/core/CL/ICLDistribution1D.h"
#include "arm_compute/core/CL/ICLLut.h"
#include "arm_compute/core/CL/OpenCL.h"
#include "arm_compute/core/Types.h"
#include "arm_compute/runtime/CL/CLScheduler.h"
#include <algorithm>
#include <cmath>
#include <cstddef>
#include <numeric>
using namespace arm_compute;
namespace
{
void calculate_cum_dist_and_lut(CLDistribution1D &dist, CLDistribution1D &cum_dist, CLLut &lut)
{
dist.map(true);
cum_dist.map(true);
lut.map(true);
const uint32_t *dist_ptr = dist.buffer();
uint32_t *cum_dist_ptr = cum_dist.buffer();
uint8_t *lut_ptr = lut.buffer();
ARM_COMPUTE_ERROR_ON(dist_ptr == nullptr);
ARM_COMPUTE_ERROR_ON(cum_dist_ptr == nullptr);
ARM_COMPUTE_ERROR_ON(lut_ptr == nullptr);
// Calculate cumulative distribution
std::partial_sum(dist_ptr, dist_ptr + 256, cum_dist_ptr);
// Get the number of pixels that have the lowest value in the input image
const uint32_t num_lowest_pixels = *std::find_if(dist_ptr, dist_ptr + 256, [](const uint32_t &v)
{
return v > 0;
});
const size_t image_size = cum_dist_ptr[255];
if(image_size == num_lowest_pixels)
{
std::iota(lut_ptr, lut_ptr + 256, 0);
}
else
{
const float diff = image_size - num_lowest_pixels;
for(size_t i = 0; i < 256; ++i)
{
lut_ptr[i] = lround((cum_dist_ptr[i] - num_lowest_pixels) / diff * 255.f);
}
}
dist.unmap();
cum_dist.unmap();
lut.unmap();
}
} // namespace
CLEqualizeHistogram::CLEqualizeHistogram()
: _histogram_kernel(), _border_histogram_kernel(), _map_histogram_kernel(), _hist(nr_bins, 0, max_range), _cum_dist(nr_bins, 0, max_range), _cd_lut(nr_bins, DataType::U8)
{
}
void CLEqualizeHistogram::configure(const ICLImage *input, ICLImage *output)
{
configure(CLKernelLibrary::get().get_compile_context(), input, output);
}
void CLEqualizeHistogram::configure(const CLCompileContext &compile_context, const ICLImage *input, ICLImage *output)
{
_histogram_kernel.configure(compile_context, input, &_hist);
_border_histogram_kernel.configure(compile_context, input, &_hist);
_map_histogram_kernel.configure(compile_context, input, &_cd_lut, output);
}
void CLEqualizeHistogram::run()
{
// Calculate histogram of input.
CLScheduler::get().enqueue(_histogram_kernel, false);
// Calculate remaining pixels when image is not multiple of the elements of histogram kernel
CLScheduler::get().enqueue(_border_histogram_kernel, false);
// Calculate cumulative distribution of histogram and create LUT.
calculate_cum_dist_and_lut(_hist, _cum_dist, _cd_lut);
// Map input to output using created LUT.
CLScheduler::get().enqueue(_map_histogram_kernel);
}
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