1 /*
2 * Copyright (c) 2016-2020 Arm Limited.
3 *
4 * SPDX-License-Identifier: MIT
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to
8 * deal in the Software without restriction, including without limitation the
9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in all
14 * copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 */
24 #include "arm_compute/runtime/CL/functions/CLEqualizeHistogram.h"
25
26 #include "arm_compute/core/CL/ICLDistribution1D.h"
27 #include "arm_compute/core/CL/ICLLut.h"
28 #include "arm_compute/core/CL/OpenCL.h"
29 #include "arm_compute/core/Types.h"
30 #include "arm_compute/runtime/CL/CLScheduler.h"
31 #include "src/core/CL/kernels/CLHistogramKernel.h"
32 #include "src/core/CL/kernels/CLTableLookupKernel.h"
33 #include "support/MemorySupport.h"
34
35 #include <algorithm>
36 #include <cmath>
37 #include <cstddef>
38 #include <numeric>
39
40 using namespace arm_compute;
41
42 namespace
43 {
calculate_cum_dist_and_lut(CLDistribution1D & dist,CLDistribution1D & cum_dist,CLLut & lut)44 void calculate_cum_dist_and_lut(CLDistribution1D &dist, CLDistribution1D &cum_dist, CLLut &lut)
45 {
46 dist.map(true);
47 cum_dist.map(true);
48 lut.map(true);
49
50 const uint32_t *dist_ptr = dist.buffer();
51 uint32_t *cum_dist_ptr = cum_dist.buffer();
52 uint8_t *lut_ptr = lut.buffer();
53
54 ARM_COMPUTE_ERROR_ON(dist_ptr == nullptr);
55 ARM_COMPUTE_ERROR_ON(cum_dist_ptr == nullptr);
56 ARM_COMPUTE_ERROR_ON(lut_ptr == nullptr);
57
58 // Calculate cumulative distribution
59 std::partial_sum(dist_ptr, dist_ptr + 256, cum_dist_ptr);
60
61 // Get the number of pixels that have the lowest value in the input image
62 const uint32_t num_lowest_pixels = *std::find_if(dist_ptr, dist_ptr + 256, [](const uint32_t &v)
63 {
64 return v > 0;
65 });
66 const size_t image_size = cum_dist_ptr[255];
67
68 if(image_size == num_lowest_pixels)
69 {
70 std::iota(lut_ptr, lut_ptr + 256, 0);
71 }
72 else
73 {
74 const float diff = image_size - num_lowest_pixels;
75
76 for(size_t i = 0; i < 256; ++i)
77 {
78 lut_ptr[i] = lround((cum_dist_ptr[i] - num_lowest_pixels) / diff * 255.f);
79 }
80 }
81
82 dist.unmap();
83 cum_dist.unmap();
84 lut.unmap();
85 }
86 } // namespace
87
CLEqualizeHistogram()88 CLEqualizeHistogram::CLEqualizeHistogram()
89 : _histogram_kernel(support::cpp14::make_unique<CLHistogramKernel>()),
90 _border_histogram_kernel(support::cpp14::make_unique<CLHistogramBorderKernel>()),
91 _map_histogram_kernel(support::cpp14::make_unique<CLTableLookupKernel>()),
92 _hist(nr_bins, 0, max_range),
93 _cum_dist(nr_bins, 0, max_range),
94 _cd_lut(nr_bins, DataType::U8)
95 {
96 }
97
98 CLEqualizeHistogram::~CLEqualizeHistogram() = default;
99
configure(const ICLImage * input,ICLImage * output)100 void CLEqualizeHistogram::configure(const ICLImage *input, ICLImage *output)
101 {
102 configure(CLKernelLibrary::get().get_compile_context(), input, output);
103 }
104
configure(const CLCompileContext & compile_context,const ICLImage * input,ICLImage * output)105 void CLEqualizeHistogram::configure(const CLCompileContext &compile_context, const ICLImage *input, ICLImage *output)
106 {
107 _histogram_kernel->configure(compile_context, input, &_hist);
108 _border_histogram_kernel->configure(compile_context, input, &_hist);
109 _map_histogram_kernel->configure(compile_context, input, &_cd_lut, output);
110 }
111
run()112 void CLEqualizeHistogram::run()
113 {
114 // Calculate histogram of input.
115 CLScheduler::get().enqueue(*_histogram_kernel, false);
116
117 // Calculate remaining pixels when image is not multiple of the elements of histogram kernel
118 CLScheduler::get().enqueue(*_border_histogram_kernel, false);
119
120 // Calculate cumulative distribution of histogram and create LUT.
121 calculate_cum_dist_and_lut(_hist, _cum_dist, _cd_lut);
122
123 // Map input to output using created LUT.
124 CLScheduler::get().enqueue(*_map_histogram_kernel);
125 }
126