Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 1 | /* |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 2 | * Copyright (c) 2016-2019 ARM Limited. |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 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/core/NEON/kernels/NEFastCornersKernel.h" |
| 25 | |
| 26 | #include "arm_compute/core/Coordinates.h" |
| 27 | #include "arm_compute/core/Error.h" |
| 28 | #include "arm_compute/core/Helpers.h" |
| 29 | #include "arm_compute/core/Validate.h" |
| 30 | |
| 31 | #include <algorithm> |
| 32 | #include <arm_neon.h> |
| 33 | #include <cstddef> |
| 34 | #include <limits> |
| 35 | |
| 36 | using namespace arm_compute; |
| 37 | |
| 38 | NEFastCornersKernel::NEFastCornersKernel() |
| 39 | : INEKernel(), _input(nullptr), _output(nullptr), _threshold(0), _non_max_suppression(false) |
| 40 | { |
| 41 | } |
| 42 | |
| 43 | namespace |
| 44 | { |
| 45 | constexpr size_t PERMUTATIONS = 16; |
| 46 | constexpr size_t PERM_SIZE = 16; |
| 47 | |
| 48 | inline uint8x8x2_t create_permutation_index(size_t k) |
| 49 | { |
| 50 | ARM_COMPUTE_ERROR_ON(k >= PERMUTATIONS); |
| 51 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 52 | static const std::array<std::array<uint8_t, PERMUTATIONS>, PERM_SIZE> permutations_table{ { { 0, 1, 2, 3, 4, 5, 6, 7, 8, 255, 255, 255, 255, 255, 255, 255 }, |
| 53 | { 15, 0, 1, 2, 3, 4, 5, 6, 7, 255, 255, 255, 255, 255, 255, 255 }, |
| 54 | { 14, 15, 0, 1, 2, 3, 4, 5, 6, 255, 255, 255, 255, 255, 255, 255 }, |
| 55 | { 13, 14, 15, 0, 1, 2, 3, 4, 5, 255, 255, 255, 255, 255, 255, 255 }, |
| 56 | { 12, 13, 14, 15, 0, 1, 2, 3, 4, 255, 255, 255, 255, 255, 255, 255 }, |
| 57 | { 11, 12, 13, 14, 15, 0, 1, 2, 3, 255, 255, 255, 255, 255, 255, 255 }, |
| 58 | { 10, 11, 12, 13, 14, 15, 0, 1, 2, 255, 255, 255, 255, 255, 255, 255 }, |
| 59 | { 9, 10, 11, 12, 13, 14, 15, 0, 1, 255, 255, 255, 255, 255, 255, 255 }, |
| 60 | { 8, 9, 10, 11, 12, 13, 14, 15, 0, 255, 255, 255, 255, 255, 255, 255 }, |
| 61 | { 7, 8, 9, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255 }, |
| 62 | { 6, 7, 8, 9, 10, 11, 12, 13, 14, 255, 255, 255, 255, 255, 255, 255 }, |
| 63 | { 5, 6, 7, 8, 9, 10, 11, 12, 13, 255, 255, 255, 255, 255, 255, 255 }, |
| 64 | { 4, 5, 6, 7, 8, 9, 10, 11, 12, 255, 255, 255, 255, 255, 255, 255 }, |
| 65 | { 3, 4, 5, 6, 7, 8, 9, 10, 11, 255, 255, 255, 255, 255, 255, 255 }, |
| 66 | { 2, 3, 4, 5, 6, 7, 8, 9, 10, 255, 255, 255, 255, 255, 255, 255 }, |
| 67 | { 1, 2, 3, 4, 5, 6, 7, 8, 9, 255, 255, 255, 255, 255, 255, 255 } |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 68 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 69 | } }; |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 70 | |
| 71 | const uint8x8x2_t index = |
| 72 | { |
| 73 | { |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 74 | vld1_u8(permutations_table[k].data()), |
| 75 | vld1_u8(permutations_table[k].data() + 8) |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 76 | } |
| 77 | }; |
| 78 | |
| 79 | return index; |
| 80 | } |
| 81 | |
| 82 | inline uint8x8x4_t create_circle_index_register() |
| 83 | { |
| 84 | /* |
| 85 | This function creates the index registers to retrieve the 16 texels in the Bresenham circle of radius 3 with center in P. |
| 86 | |
| 87 | . . F 0 1 . . . |
| 88 | . E . . . 2 . . |
| 89 | D . . . . . 3 . |
| 90 | C . . P . . 4 . |
| 91 | B . . . . . 5 . |
| 92 | . A . . . 6 . . |
| 93 | . . 9 8 7 . . . |
| 94 | |
| 95 | Where . is an irrelevant texel value |
| 96 | |
| 97 | We want to retrieve all texels [0,F] |
| 98 | |
| 99 | The 4 registers in r will then be used to get these texels out of two tables in the function get_circle_texels() |
| 100 | |
| 101 | The first table holds the top 4 rows of texels |
| 102 | . . F 0 1 . . . |
| 103 | . E . . . 2 . . |
| 104 | D . . . . . 3 . |
| 105 | C . . P . . 4 . |
| 106 | |
| 107 | The second table the bottom 3 rows of texels |
| 108 | B . . . . . 5 . |
| 109 | . A . . . 6 . . |
| 110 | . . 9 8 7 . . . |
| 111 | |
| 112 | */ |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 113 | static const std::array<uint8_t, 8> top_right = |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 114 | { |
| 115 | /* The register r.val[0] will be used to retrieve these texels: |
| 116 | . . . 0 1 . . . |
| 117 | . . . . . 2 . . |
| 118 | . . . . . . 3 . |
| 119 | . . . . . . 4 . |
| 120 | */ |
| 121 | 3 /* top table, first row, elem 4, value 0 in the diagram above */, |
| 122 | 4 /* top table, first row, elem 5, value 1 in the diagram above */, |
| 123 | 13 /* top table, second row, elem 6, value 2 in the diagram above */, |
| 124 | 22 /* top table, third row, elem 7, value 3 in the diagram above*/, |
| 125 | 30 /* top table, fourth row, elem 7, value 4 in the diagram above*/, |
| 126 | 255, |
| 127 | 255, |
| 128 | 255 |
| 129 | }; |
| 130 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 131 | static const std::array<uint8_t, 8> bottom_right = |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 132 | { |
| 133 | /* The register r.val[1] will be used to retrieve these texels: |
| 134 | . . . . . . 5 . |
| 135 | . . . . . 6 . . |
| 136 | . . . . 7 . . . |
| 137 | */ |
| 138 | 255, |
| 139 | 255, |
| 140 | 255, |
| 141 | 255, |
| 142 | 255, |
| 143 | 6 /* low table, first row, elem 7, value 5 in the diagram above*/, |
| 144 | 13 /* low table, second row, elem 6, value 6 in the diagram above*/, |
| 145 | 20 /* low table, third row, elem 5, value 7 in the diagram above*/ |
| 146 | }; |
| 147 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 148 | static const std::array<uint8_t, 8> top_left = |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 149 | { |
| 150 | /* The register r.val[2] will be used to retrieve these texels: |
| 151 | . . F . . . . . |
| 152 | . E . . . . . . |
| 153 | D . . . . . . . |
| 154 | C . . . . . . . |
| 155 | */ |
| 156 | 255, |
| 157 | 255, |
| 158 | 255, |
| 159 | 255, |
| 160 | 24 /* top table, fourth row, elem 1, value C in the diagram above */, |
| 161 | 16 /* top table, third row, elem 1, value D in the diagram above*/, |
| 162 | 9 /* top table, second row, elem 2, value E in the diagram above*/, |
| 163 | 2 /* top table, first row, elem 3, value F in the diagram above*/ |
| 164 | }; |
| 165 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 166 | static const std::array<uint8_t, 8> bottom_left = |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 167 | { |
| 168 | /* The register r.val[3] will be used to retrieve these texels: |
| 169 | B . . . . . . . |
| 170 | . A . . . . . . |
| 171 | . . 9 8 . . . . |
| 172 | */ |
| 173 | 19 /* low table, third row, elem 4, value 8 in the diagram above */, |
| 174 | 18 /* low table, third row, elem 3, value 9 in the diagram above */, |
| 175 | 9 /* low table, second row, elem 2, value A in the diagram above */, |
| 176 | 0 /* low table, first row, elem 1, value B in the diagram above */, |
| 177 | 255, |
| 178 | 255, |
| 179 | 255, |
| 180 | 255 |
| 181 | }; |
| 182 | |
| 183 | const uint8x8x4_t reg = |
| 184 | { |
| 185 | { |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 186 | vld1_u8(top_right.data()), |
| 187 | vld1_u8(bottom_right.data()), |
| 188 | vld1_u8(top_left.data()), |
| 189 | vld1_u8(bottom_left.data()) |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 190 | } |
| 191 | }; |
| 192 | |
| 193 | return reg; |
| 194 | } |
| 195 | |
| 196 | inline uint8x16_t get_circle_texels(const uint8x8x4_t &index, const uint8x8x4_t &tbl_hi, const uint8x8x3_t &tbl_lo) |
| 197 | { |
| 198 | /* |
| 199 | This function loads the 16 texels in the Bresenham circle of radius 3 into the register 'texels'. |
| 200 | The parameter 'index' is an array of indices which was previously setup in setup_circle_index_register(). |
| 201 | tbl_hi and tbl_lo are the two tables holding the texels in the window [(-3,-3),(+3,+3)] for a given texel P |
| 202 | */ |
| 203 | return vcombine_u8(vtbx3_u8(vtbl4_u8(tbl_hi, index.val[0]), tbl_lo, index.val[1]), |
| 204 | vtbx3_u8(vtbl4_u8(tbl_hi, index.val[2]), tbl_lo, index.val[3])); |
| 205 | } |
| 206 | |
| 207 | inline uint8x16_t get_permutation_texels(const uint8x8x2_t &permutation_index, const uint8x8x2_t &tbl_circle) |
| 208 | { |
| 209 | /* |
| 210 | This function stores the 9 texels of a give permutation X in the neon register 'texels' |
| 211 | |
| 212 | 'tbl_circle' is a LUT with the texels 0 to F |
| 213 | |
| 214 | . . F 0 1 . . . |
| 215 | . E . . . 2 . . |
| 216 | D . . . . . 3 . |
| 217 | C . . P . . 4 . |
| 218 | B . . . . . 5 . |
| 219 | . A . . . 6 . . |
| 220 | . . 9 8 7 . . . |
| 221 | |
| 222 | 'permutation_index' is one of the permutations below: |
| 223 | |
| 224 | { 0, 1, 2, 3, 4, 5, 6, 7, 8}, |
| 225 | { F, 0, 1, 2, 3, 4, 5, 6, 7}, |
| 226 | { E, F, 0, 1, 2, 3, 4, 5, 6}, |
| 227 | { D, E, F, 0, 1, 2, 3, 4, 5}, |
| 228 | { C, D, E, F, 0, 1, 2, 3, 4}, |
| 229 | { B, C, D, E, F, 0, 1, 2, 3}, |
| 230 | { A, B, C, D, E, F, 0, 1, 2}, |
| 231 | { 9, A, B, C, D, E, F, 0, 1}, |
| 232 | { 8, 9, A, B, C, D, E, F, 0}, |
| 233 | { 7, 8, 9, A, B, C, D, E, F}, |
| 234 | { 6, 7, 8, 9, A, B, C, D, E}, |
| 235 | { 5, 6, 7, 8, 9, A, B, C, D}, |
| 236 | { 4, 5, 6, 7, 8, 9, A, B, C}, |
| 237 | { 3, 4, 5, 6, 7, 8, 9, A, B}, |
| 238 | { 2, 3, 4, 5, 6, 7, 8, 9, A}, |
| 239 | { 1, 2, 3, 4, 5, 6, 7, 8, 9}, |
| 240 | */ |
| 241 | static const uint8x8_t perm_right = vdup_n_u8(255); // init to 255 so that vtbx preserves the original values of the lanes |
| 242 | |
| 243 | return vcombine_u8(vtbl2_u8(tbl_circle, permutation_index.val[0]), |
| 244 | vtbx2_u8(perm_right, tbl_circle, permutation_index.val[1])); |
| 245 | } |
| 246 | |
| 247 | inline bool is_permutation_brighter(const uint8x16_t &permutation, const uint8x16_t &pg) |
| 248 | { |
| 249 | const uint8x16_t res_gt = vcgtq_u8(permutation, pg); |
| 250 | |
| 251 | return vget_lane_u64(vreinterpret_u64_u8(vand_u8(vget_high_u8(res_gt), vget_low_u8(res_gt))), 0) == std::numeric_limits<uint64_t>::max(); |
| 252 | } |
| 253 | |
| 254 | inline bool is_permutation_darker(const uint8x16_t &permutation, const uint8x16_t &pl) |
| 255 | { |
| 256 | const uint8x16_t res_lt = vcltq_u8(permutation, pl); |
| 257 | const uint64x2_t u64res_lt = vreinterpretq_u64_u8(res_lt); |
| 258 | const uint64_t t3 = vgetq_lane_u64(u64res_lt, 0); |
| 259 | const uint64_t t4 = vgetq_lane_u64(u64res_lt, 1); |
| 260 | |
| 261 | return std::numeric_limits<uint64_t>::max() == t3 && 255 == t4; |
| 262 | } |
| 263 | |
| 264 | inline bool is_permutation_corner(const uint8x16_t &permutation, const uint8x16_t &pg, const uint8x16_t &pl) |
| 265 | { |
| 266 | return is_permutation_brighter(permutation, pg) || is_permutation_darker(permutation, pl); |
| 267 | } |
| 268 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 269 | inline bool point_is_fast_corner(uint8_t p, uint8_t threshold, const uint8x8x2_t &tbl_circle_texels, std::array<uint8x8x2_t, PERMUTATIONS> &perm_indices) |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 270 | { |
| 271 | /* |
| 272 | This function determines whether the point 'p' is a corner. |
| 273 | */ |
| 274 | uint8x16_t pg = vqaddq_u8(vdupq_n_u8(p), vdupq_n_u8(threshold)); |
| 275 | uint8x16_t pl = vqsubq_u8(vdupq_n_u8(p), vdupq_n_u8(threshold)); |
| 276 | |
| 277 | bool corner_detected = false; |
| 278 | |
| 279 | for(size_t j = 0; !corner_detected && j < PERMUTATIONS; ++j) |
| 280 | { |
| 281 | const uint8x16_t pe_texels = get_permutation_texels(perm_indices[j], tbl_circle_texels); |
| 282 | corner_detected = is_permutation_corner(pe_texels, pg, pl); |
| 283 | } |
| 284 | |
| 285 | return corner_detected; |
| 286 | } |
| 287 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 288 | inline uint8x8x2_t create_circle_tbl(const std::array<uint8_t *const __restrict, 7> &buffer, size_t in_offset, const uint8x8x4_t &circle_index_r) |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 289 | { |
| 290 | /* |
| 291 | This function builds a LUT holding the 16 texels in the Brensenham circle radius 3. |
| 292 | circle_index_r is a vector of 4 registers to retrieve the texels from the two tables mentioned above. |
| 293 | */ |
| 294 | |
| 295 | //Load the texels in the window [(x-3,y-3),(x+3,y+3)]. |
| 296 | //The top 4 rows are loaded in tbl_hi and the low 3 rows in tbl_lo. |
| 297 | //These two tables are then used to retrieve the texels in the Bresenham circle of radius 3. |
| 298 | const uint8x8x4_t tbl_window_hi = |
| 299 | { |
| 300 | { |
| 301 | vld1_u8(buffer[0] + in_offset), |
| 302 | vld1_u8(buffer[1] + in_offset), |
| 303 | vld1_u8(buffer[2] + in_offset), |
| 304 | vld1_u8(buffer[3] + in_offset) |
| 305 | } |
| 306 | }; |
| 307 | |
| 308 | const uint8x8x3_t tbl_window_lo = |
| 309 | { |
| 310 | { |
| 311 | vld1_u8(buffer[4] + in_offset), |
| 312 | vld1_u8(buffer[5] + in_offset), |
| 313 | vld1_u8(buffer[6] + in_offset) |
| 314 | } |
| 315 | }; |
| 316 | |
| 317 | const uint8x16_t circle_texels = get_circle_texels(circle_index_r, tbl_window_hi, tbl_window_lo); |
| 318 | |
| 319 | const uint8x8x2_t tbl_circle_texels = |
| 320 | { |
| 321 | { |
| 322 | vget_low_u8(circle_texels), |
| 323 | vget_high_u8(circle_texels) |
| 324 | } |
| 325 | }; |
| 326 | |
| 327 | return tbl_circle_texels; |
| 328 | } |
| 329 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 330 | inline uint8_t get_point_score(uint8_t p, uint8_t tolerance, const uint8x8x2_t &tbl_circle, std::array<uint8x8x2_t, PERMUTATIONS> &perm_indices) |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 331 | { |
| 332 | uint8_t b = 255; |
| 333 | uint8_t a = tolerance; |
| 334 | |
| 335 | while(b - a > 1) |
| 336 | { |
| 337 | const uint16_t ab = a + b; |
| 338 | const uint8_t c = ab >> 1; |
| 339 | |
| 340 | if(point_is_fast_corner(p, c, tbl_circle, perm_indices)) |
| 341 | { |
| 342 | a = c; |
| 343 | } |
| 344 | else |
| 345 | { |
| 346 | b = c; |
| 347 | } |
| 348 | } |
| 349 | |
| 350 | return a; |
| 351 | } |
| 352 | } // namespace |
| 353 | |
| 354 | BorderSize NEFastCornersKernel::border_size() const |
| 355 | { |
| 356 | return BorderSize(3); |
| 357 | } |
| 358 | |
| 359 | void NEFastCornersKernel::configure(const IImage *input, IImage *output, uint8_t threshold, bool non_max_suppression, bool border_undefined) |
| 360 | { |
| 361 | ARM_COMPUTE_ERROR_ON_TENSOR_NOT_2D(input); |
| 362 | ARM_COMPUTE_ERROR_ON_TENSOR_NOT_2D(output); |
| 363 | ARM_COMPUTE_ERROR_ON_DATA_TYPE_CHANNEL_NOT_IN(input, 1, DataType::U8); |
| 364 | ARM_COMPUTE_ERROR_ON_DATA_TYPE_CHANNEL_NOT_IN(output, 1, DataType::U8); |
| 365 | ARM_COMPUTE_ERROR_ON_MSG(border_undefined == false, "Not implemented"); |
| 366 | |
| 367 | _input = input; |
| 368 | _output = output; |
| 369 | _threshold = threshold; |
| 370 | _non_max_suppression = non_max_suppression; |
| 371 | |
| 372 | constexpr unsigned int num_elems_processed_per_iteration = 1; |
| 373 | constexpr unsigned int num_elems_read_per_iteration = 8; |
| 374 | constexpr unsigned int num_elems_written_per_iteration = 1; |
| 375 | constexpr unsigned int num_rows_read_per_iteration = 7; |
| 376 | |
| 377 | // Configure kernel window |
| 378 | Window win = calculate_max_window(*input->info(), Steps(num_elems_processed_per_iteration), border_undefined, border_size()); |
| 379 | AccessWindowHorizontal output_access(output->info(), 0, num_elems_written_per_iteration); |
| 380 | AccessWindowRectangle input_access(input->info(), -border_size().left, -border_size().top, num_elems_read_per_iteration, num_rows_read_per_iteration); |
| 381 | |
| 382 | update_window_and_padding(win, input_access, output_access); |
| 383 | |
| 384 | output_access.set_valid_region(win, input->info()->valid_region(), border_undefined, border_size()); |
| 385 | |
| 386 | INEKernel::configure(win); |
| 387 | } |
| 388 | |
Moritz Pflanzer | c186b57 | 2017-09-07 09:48:04 +0100 | [diff] [blame] | 389 | void NEFastCornersKernel::run(const Window &window, const ThreadInfo &info) |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 390 | { |
Moritz Pflanzer | c186b57 | 2017-09-07 09:48:04 +0100 | [diff] [blame] | 391 | ARM_COMPUTE_UNUSED(info); |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 392 | ARM_COMPUTE_ERROR_ON_UNCONFIGURED_KERNEL(this); |
| 393 | ARM_COMPUTE_ERROR_ON_INVALID_SUBWINDOW(INEKernel::window(), window); |
| 394 | |
| 395 | std::array<uint8x8x2_t, PERMUTATIONS> perm_index{ {} }; |
| 396 | /* |
| 397 | We use a LUT loaded with 7 rows of uint8_t from the input image [-3,-3]...[+3,+3] to retrieve the texels in the Brensenham circle radius 3 and put them in one neon register uint8x16_t. |
| 398 | The three lines below setup the neon index registers to get these texels out from the table |
| 399 | */ |
| 400 | const uint8x8x4_t circle_index_r = create_circle_index_register(); |
| 401 | /* |
| 402 | We put the 16 texels (circle) in a LUT to easily generate all the permutations. The for block below setups the indices for each permutation. |
| 403 | */ |
| 404 | for(size_t k = 0; k < PERMUTATIONS; ++k) |
| 405 | { |
| 406 | perm_index[k] = create_permutation_index(k); |
| 407 | } |
| 408 | |
| 409 | Iterator in(_input, window); |
| 410 | Iterator out(_output, window); |
| 411 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 412 | const std::array<uint8_t *const __restrict, 7> in_row |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 413 | { |
| 414 | _input->ptr_to_element(Coordinates(-3, -3)), |
| 415 | _input->ptr_to_element(Coordinates(-3, -2)), |
| 416 | _input->ptr_to_element(Coordinates(-3, -1)), |
| 417 | _input->ptr_to_element(Coordinates(-3, 0)), |
| 418 | _input->ptr_to_element(Coordinates(-3, 1)), |
| 419 | _input->ptr_to_element(Coordinates(-3, 2)), |
| 420 | _input->ptr_to_element(Coordinates(-3, 3)) |
| 421 | }; |
| 422 | |
| 423 | auto is_rejected = [](uint8_t p, uint8_t q, uint8_t a, uint8_t b) |
| 424 | { |
| 425 | const bool p_is_in_ab = (a <= p) && (p <= b); |
| 426 | const bool q_is_in_ab = (a <= q) && (q <= b); |
| 427 | return p_is_in_ab && q_is_in_ab; |
| 428 | }; |
| 429 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 430 | execute_window_loop(window, [&](const Coordinates &) |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 431 | { |
| 432 | const size_t in_offset = in.offset(); |
| 433 | const uint8_t p0 = *in.ptr(); |
| 434 | const uint8_t b = std::min(p0 + _threshold, 255); |
| 435 | const uint8_t a = std::max(p0 - _threshold, 0); |
| 436 | uint8_t score = 0; |
| 437 | /* |
| 438 | Fast check to discard points which cannot be corners and avoid the expensive computation of the potential 16 permutations |
| 439 | |
| 440 | pixels 1 and 9 are examined, if both I1 and I9 are within [Ip - t, Ip + t], then candidate p is not a corner. |
| 441 | */ |
| 442 | const uint8_t p1 = (in_offset + in_row[0])[3]; |
| 443 | const uint8_t p9 = (in_offset + in_row[6])[3]; |
| 444 | |
| 445 | if(!is_rejected(p1, p9, a, b)) |
| 446 | { |
| 447 | /* pixels 5 and 13 are further examined to check whether three of them are brighter than Ip + t or darker than Ip - t */ |
| 448 | const uint8_t p5 = (in_offset + in_row[3])[6]; |
| 449 | const uint8_t p13 = (in_offset + in_row[3])[0]; |
| 450 | |
| 451 | if(!is_rejected(p5, p13, a, b)) |
| 452 | { |
| 453 | /* at this stage we use the full test with the 16 permutations to classify the point as corner or not */ |
| 454 | const uint8x8x2_t tbl_circle_texel = create_circle_tbl(in_row, in_offset, circle_index_r); |
| 455 | |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 456 | if(point_is_fast_corner(p0, _threshold, tbl_circle_texel, perm_index)) |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 457 | { |
| 458 | if(_non_max_suppression) |
| 459 | { |
Michalis Spyrou | a4f378d | 2019-04-26 14:54:54 +0100 | [diff] [blame] | 460 | score = get_point_score(p0, _threshold, tbl_circle_texel, perm_index); |
Anthony Barbier | 6ff3b19 | 2017-09-04 18:44:23 +0100 | [diff] [blame] | 461 | } |
| 462 | else |
| 463 | { |
| 464 | score = 1; |
| 465 | } |
| 466 | } |
| 467 | } |
| 468 | } |
| 469 | |
| 470 | *out.ptr() = score; |
| 471 | }, |
| 472 | in, out); |
| 473 | } |