94 lines
2.8 KiB
C++
94 lines
2.8 KiB
C++
/*
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* Copyright (c) 2017-2020 Arm Limited.
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*
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* SPDX-License-Identifier: MIT
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include "EqualizeHistogram.h"
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namespace arm_compute
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{
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namespace test
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{
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namespace validation
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{
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namespace reference
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{
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template <typename T>
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SimpleTensor<T> equalize_histogram(const SimpleTensor<T> &src)
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{
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const size_t num_bins = 256; // 0-255 inclusive
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std::vector<T> lut(num_bins);
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std::vector<uint32_t> hist(num_bins);
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std::vector<uint32_t> cd(num_bins); // cumulative distribution
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SimpleTensor<T> dst(src.shape(), src.data_type());
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// Create the histogram
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for(int element_idx = 0; element_idx < src.num_elements(); ++element_idx)
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{
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hist[src[element_idx]]++;
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}
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// Calculate cumulative distribution
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std::partial_sum(hist.begin(), hist.end(), cd.begin());
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// Get the number of pixels that have the lowest non-zero value
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const uint32_t cd_min = *std::find_if(hist.begin(), hist.end(), [](const uint32_t &x)
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{
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return x > 0;
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});
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const size_t total_num_pixels = cd.back();
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// Single color - create linear distribution
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if(total_num_pixels == cd_min)
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{
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std::iota(lut.begin(), lut.end(), 0);
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}
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else
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{
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const float diff = total_num_pixels - cd_min;
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for(size_t i = 0; i < num_bins; ++i)
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{
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lut[i] = lround((cd[i] - cd_min) / diff * 255.f);
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}
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}
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// Fill output tensor with equalized values
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#if defined(_OPENMP)
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#pragma omp parallel for
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#endif /* _OPENMP */
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for(int i = 0; i < src.num_elements(); ++i)
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{
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dst[i] = lut[src[i]];
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}
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return dst;
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}
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template SimpleTensor<uint8_t> equalize_histogram(const SimpleTensor<uint8_t> &src);
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} // namespace reference
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} // namespace validation
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} // namespace test
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} // namespace arm_compute
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