| /* |
| * Copyright (c) 2017-2018 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 "EqualizeHistogram.h" |
| |
| namespace arm_compute |
| { |
| namespace test |
| { |
| namespace validation |
| { |
| namespace reference |
| { |
| template <typename T> |
| SimpleTensor<T> equalize_histogram(const SimpleTensor<T> &src) |
| { |
| const size_t num_bins = 256; // 0-255 inclusive |
| |
| std::vector<T> lut(num_bins); |
| std::vector<uint32_t> hist(num_bins); |
| std::vector<uint32_t> cd(num_bins); // cumulative distribution |
| |
| SimpleTensor<T> dst(src.shape(), src.data_type()); |
| |
| // Create the histogram |
| for(int element_idx = 0; element_idx < src.num_elements(); ++element_idx) |
| { |
| hist[src[element_idx]]++; |
| } |
| |
| // Calculate cumulative distribution |
| std::partial_sum(hist.begin(), hist.end(), cd.begin()); |
| |
| // Get the number of pixels that have the lowest non-zero value |
| const uint32_t cd_min = *std::find_if(hist.begin(), hist.end(), [](const uint32_t &x) |
| { |
| return x > 0; |
| }); |
| |
| const size_t total_num_pixels = cd.back(); |
| |
| // Single color - create linear distribution |
| if(total_num_pixels == cd_min) |
| { |
| std::iota(lut.begin(), lut.end(), 0); |
| } |
| else |
| { |
| const float diff = total_num_pixels - 1; |
| |
| for(size_t i = 0; i < num_bins; ++i) |
| { |
| lut[i] = lround((cd[i] - cd_min) / diff * 255.f); |
| } |
| } |
| |
| // Fill output tensor with equalized values |
| for(int i = 0; i < src.num_elements(); ++i) |
| { |
| dst[i] = lut[src[i]]; |
| } |
| |
| return dst; |
| } |
| |
| template SimpleTensor<uint8_t> equalize_histogram(const SimpleTensor<uint8_t> &src); |
| } // namespace reference |
| } // namespace validation |
| } // namespace test |
| } // namespace arm_compute |