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| 1 | +// This file is part of the AliceVision project. |
| 2 | +// Copyright (c) 2025 AliceVision contributors. |
| 3 | +// This Source Code Form is subject to the terms of the Mozilla Public License, |
| 4 | +// v. 2.0. If a copy of the MPL was not distributed with this file, |
| 5 | +// You can obtain one at https://mozilla.org/MPL/2.0/. |
| 6 | + |
| 7 | +#pragma once |
| 8 | + |
| 9 | +#include <aliceVision/image/Image.hpp> |
| 10 | +#include <aliceVision/image/Sampler.hpp> |
| 11 | +#include <aliceVision/system/Logger.hpp> |
| 12 | +#include <type_traits> |
| 13 | + |
| 14 | +namespace aliceVision { |
| 15 | +namespace image { |
| 16 | + |
| 17 | +/** |
| 18 | + * @brief Fill pixels of an image such that dest(i, j) = input(map(i, j).y, map(i, j).x) |
| 19 | + * @param[in] src source image (of size H1,W1) to remap |
| 20 | + * @param[in] map image (of size H2, W2) containing coordinates in the source image |
| 21 | + * @param[in] fillColor the default pixel value if not possible to remap |
| 22 | + * @param[out] output image to store the result (will be resized to size H2, W2) |
| 23 | + */ |
| 24 | +template <typename P> |
| 25 | +void remap( const Image<P> & source, const Image<Vec2> & map, const P & fillColor, Image<P> & output) |
| 26 | +{ |
| 27 | + if (output.width() != map.width() || output.height() != map.height()) |
| 28 | + { |
| 29 | + output.resize(map.width(), map.height()); |
| 30 | + } |
| 31 | + |
| 32 | + const image::Sampler2d<image::SamplerLinear> sampler; |
| 33 | + |
| 34 | + for (int i = 0; i < map.height(); i++) |
| 35 | + { |
| 36 | + for (int j = 0; j < map.width(); j++) |
| 37 | + { |
| 38 | + const Vec2 & coord = map(i, j); |
| 39 | + |
| 40 | + const double & x = coord.x(); |
| 41 | + const double & y = coord.y(); |
| 42 | + |
| 43 | + // pick pixel if it is in the image domain |
| 44 | + if (source.contains(y, x)) |
| 45 | + { |
| 46 | + output(i, j) = sampler(source, y, x); |
| 47 | + } |
| 48 | + else |
| 49 | + { |
| 50 | + output(i, j) = fillColor; |
| 51 | + } |
| 52 | + } |
| 53 | + } |
| 54 | +} |
| 55 | + |
| 56 | +/** |
| 57 | + * @brief Fill pixels of an image such that dest(i, j) = input(map(i, j).y, map(i, j).x) |
| 58 | + * @param[in] src source image (of size H1,W1) to remap |
| 59 | + * @param[in] map image (of size H2, W2) containing coordinates in the source image |
| 60 | + * @param[in] fillColor the default pixel value if not possible to remap |
| 61 | + * @param[out] output image to store the result (will be resized to size H2, W2) |
| 62 | + */ |
| 63 | +template <typename P> |
| 64 | +void remapInter( const Image<P> & source, const Image<Vec2> & map, const P& fillColor, Image<P> & output) |
| 65 | +{ |
| 66 | + if (output.width() != map.width() || output.height() != map.height()) |
| 67 | + { |
| 68 | + output.resize(map.width(), map.height()); |
| 69 | + } |
| 70 | + |
| 71 | + int srcWidth = source.width(); |
| 72 | + int srcHeight = source.height(); |
| 73 | + |
| 74 | + const image::Sampler2d<image::SamplerLinear> sampler; |
| 75 | + |
| 76 | + for (int i = 0; i < map.height(); i++) |
| 77 | + { |
| 78 | + for (int j = 0; j < map.width(); j++) |
| 79 | + { |
| 80 | + const Vec2 & coord = map(i, j); |
| 81 | + |
| 82 | + const double & x = coord.x(); |
| 83 | + const double & y = coord.y(); |
| 84 | + |
| 85 | + double scaleX = 1.0; |
| 86 | + if (j < map.width() - 1 && j > 0) |
| 87 | + { |
| 88 | + scaleX = std::abs(map(i, j + 1).x() - map(i, j - 1).x()) * 0.5; |
| 89 | + } |
| 90 | + else if (j < map.width() - 1) |
| 91 | + { |
| 92 | + scaleX = std::abs(map(i, j + 1).x() - x); |
| 93 | + } |
| 94 | + else if (j > 0) |
| 95 | + { |
| 96 | + scaleX = std::abs(x - map(i, j - 1).x()); |
| 97 | + } |
| 98 | + |
| 99 | + double scaleY = 1.0; |
| 100 | + if (i < map.height() - 1 && i > 0) |
| 101 | + { |
| 102 | + scaleY = std::abs(map(i + 1, j).y() - map(i - 1, j).y()) * 0.5; |
| 103 | + } |
| 104 | + else if (i < map.height() - 1) |
| 105 | + { |
| 106 | + scaleY = std::abs(map(i + 1, j).y() - y); |
| 107 | + } |
| 108 | + else if (i > 0) |
| 109 | + { |
| 110 | + scaleY = std::abs(y - map(i - 1, j).y()); |
| 111 | + } |
| 112 | + |
| 113 | + const double max_scale = std::max(scaleX, scaleY); |
| 114 | + if (scaleX > 1.0 && scaleY > 1.0) |
| 115 | + { |
| 116 | + //We are doing downsampling here. |
| 117 | + //Use area interpolation to avoid aliasing |
| 118 | + |
| 119 | + double halfWidth = scaleX * 0.5; |
| 120 | + double halfHeight = scaleY * 0.5; |
| 121 | + |
| 122 | + double x1 = coord.x() - halfWidth; |
| 123 | + double x2 = coord.x() + halfWidth; |
| 124 | + double y1 = coord.y() - halfHeight; |
| 125 | + double y2 = coord.y() + halfHeight; |
| 126 | + |
| 127 | + int ix1 = static_cast<int>(x1); |
| 128 | + int ix2 = static_cast<int>(std::ceil(x2)); |
| 129 | + int iy1 = static_cast<int>(y1); |
| 130 | + int iy2 = static_cast<int>(std::ceil(y2)); |
| 131 | + |
| 132 | + //Not using sampler as the neigborhood size is dynamic |
| 133 | + |
| 134 | + P sum; |
| 135 | + sum.fill(0.0); |
| 136 | + |
| 137 | + double wsum = 0.0; |
| 138 | + |
| 139 | + for (int by = iy1; by < iy2; by++) |
| 140 | + { |
| 141 | + if (by < 0 || by >= srcHeight) |
| 142 | + { |
| 143 | + continue; |
| 144 | + } |
| 145 | + |
| 146 | + //Compute vertical occupancy |
| 147 | + // (by + 1) - y1 |
| 148 | + // or y2 - by |
| 149 | + double yocc = std::max(0.0, std::min(double(by + 1), y2) - std::max(double(by), y1)); |
| 150 | + |
| 151 | + for (int bx = ix1; bx < ix2; bx++) |
| 152 | + { |
| 153 | + if (bx < 0 || bx >= srcWidth) |
| 154 | + { |
| 155 | + continue; |
| 156 | + } |
| 157 | + |
| 158 | + //Compute horizontal occupancy |
| 159 | + // (bx + 1) - x1 |
| 160 | + // or x2 - bx |
| 161 | + double xocc = std::max(0.0, std::min(double(bx + 1), x2) - std::max(double(bx), x1)); |
| 162 | + |
| 163 | + const P & pix = source(by, bx); |
| 164 | + double weight = yocc * xocc; |
| 165 | + |
| 166 | + if constexpr (std::is_same<P, RGBAfColor>()) |
| 167 | + { |
| 168 | + weight *= pix.a(); |
| 169 | + } |
| 170 | + |
| 171 | + sum += pix * weight; |
| 172 | + wsum += weight; |
| 173 | + } |
| 174 | + } |
| 175 | + |
| 176 | + //Output pixel is the weighted mean of the |
| 177 | + //Source pixels in the area covered by the output pixel. |
| 178 | + if (wsum > 0.0) |
| 179 | + { |
| 180 | + sum /= wsum; |
| 181 | + } |
| 182 | + |
| 183 | + output(i, j) = sum; |
| 184 | + } |
| 185 | + else |
| 186 | + { |
| 187 | + // Not downsampling, do bilinear interpolation |
| 188 | + |
| 189 | + // pick pixel if it is in the image domain |
| 190 | + if (source.contains(y, x)) |
| 191 | + { |
| 192 | + output(i, j) = sampler(source, y, x); |
| 193 | + } |
| 194 | + else |
| 195 | + { |
| 196 | + output(i, j) = fillColor; |
| 197 | + } |
| 198 | + } |
| 199 | + } |
| 200 | + } |
| 201 | +} |
| 202 | + |
| 203 | +} // namespace image |
| 204 | +} // namespace aliceVision |
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