1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 | using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Drawing; using System.Drawing.Imaging; using System.Runtime.InteropServices; /* -------------------------------------------------------- * 作者:livezingy * * 博客:http://www.livezingy.com * * 开发环境: * Visual Studio V2012 * .NET Framework 4.5 * * 版本历史: * V1.0 2015年04月29日 * 为图像瘦身 --------------------------------------------------------- */ namespace BinarizationThinning { public static class Thining { //调用此函数即可实现提取图像骨架 public static void getThinPicture(string imageSrcPath, string imageDestPath) { Bitmap bmp = new Bitmap(imageSrcPath); int Threshold = 0; Byte[,] m_SourceImage = ToBinaryArray(bmp, out Threshold); Byte[,] m_DesImage = BinarizationThinning.Thining.ThinPicture(m_SourceImage); Bitmap bmpThin = BinaryArrayToBinaryBitmap(m_DesImage); bmpThin.Save(imageDestPath, System.Drawing.Imaging.ImageFormat.Jpeg); } public static int B(Byte[,] picture, int x, int y) { return picture[x, y - 1] + picture[x + 1, y - 1] + picture[x + 1, y] + picture[x + 1, y + 1] + picture[x, y + 1] + picture[x - 1, y + 1] + picture[x - 1, y] + picture[x - 1, y - 1]; } public static int A(Byte[,] picture, int x, int y) { int counter = 0; if ((picture[x, y - 1] == 0) && (picture[x + 1, y - 1] == 1)) { counter++; } if ((picture[x + 1, y - 1] == 0) && (picture[x + 1, y] == 1)) { counter++; } if ((picture[x + 1, y] == 0) && (picture[x + 1, y + 1] == 1)) { counter++; } if ((picture[x + 1, y + 1] == 0) && (picture[x, y + 1] == 1)) { counter++; } if ((picture[x, y + 1] == 0) && (picture[x - 1, y + 1] == 1)) { counter++; } if ((picture[x - 1, y + 1] == 0) && (picture[x - 1, y] == 1)) { counter++; } if ((picture[x - 1, y] == 0) && (picture[x - 1, y - 1] == 1)) { counter++; } if ((picture[x - 1, y - 1] == 0) && (picture[x, y - 1] == 1)) { counter++; } return counter; } public static Byte[,] ThinPicture(Byte[,] newPicture) { Byte[,] picture = new Byte[newPicture.GetLength(0) + 2, newPicture.GetLength(1) + 2]; Byte[,] pictureToRemove = new Byte[newPicture.GetLength(0) + 2, newPicture.GetLength(1) + 2]; bool hasChanged; for (int i = 0; i < picture.GetLength(1); i++) { for (int j = 0; j < picture.GetLength(0); j++) { picture[j, i] = 255; pictureToRemove[j, i] = 0; } } for (int i = 0; i < newPicture.GetLength(1); i++) { for (int j = 0; j < newPicture.GetLength(0); j++) { picture[j + 1, i + 1] = newPicture[j, i]; } } for (int i = 0; i < picture.GetLength(1); i++) { for (int j = 0; j < picture.GetLength(0); j++) { picture[j, i] = picture[j, i] == 0 ? picture[j, i] = 1 : picture[j, i] = 0; } } do { hasChanged = false; for (int i = 0; i < newPicture.GetLength(1); i++) { for (int j = 0; j < newPicture.GetLength(0); j++) { if ((picture[j, i] == 1) && (2 <= B(picture, j, i)) && (B(picture, j, i) <= 6) && (A(picture, j, i) == 1) && (picture[j, i - 1] * picture[j + 1, i] * picture[j, i + 1] == 0) && (picture[j + 1, i] * picture[j, i + 1] * picture[j - 1, i] == 0)) { pictureToRemove[j, i] = 1; hasChanged = true; } } } for (int i = 0; i < newPicture.GetLength(1); i++) { for (int j = 0; j < newPicture.GetLength(0); j++) { if (pictureToRemove[j, i] == 1) { picture[j, i] = 0; pictureToRemove[j, i] = 0; } } } for (int i = 0; i < newPicture.GetLength(1); i++) { for (int j = 0; j < newPicture.GetLength(0); j++) { if ((picture[j, i] == 1) && (2 <= B(picture, j, i)) && (B(picture, j, i) <= 6) && (A(picture, j, i) == 1) && (picture[j, i - 1] * picture[j + 1, i] * picture[j - 1, i] == 0) && (picture[j, i - 1] * picture[j, i + 1] * picture[j - 1, i] == 0)) { pictureToRemove[j, i] = 1; hasChanged = true; } } } for (int i = 0; i < newPicture.GetLength(1); i++) { for (int j = 0; j < newPicture.GetLength(0); j++) { if (pictureToRemove[j, i] == 1) { picture[j, i] = 0; pictureToRemove[j, i] = 0; } } } } while (hasChanged); for (int i = 0; i < newPicture.GetLength(1); i++) { for (int j = 0; j < newPicture.GetLength(0); j++) { if ((picture[j, i] == 1) && (((picture[j, i - 1] * picture[j + 1, i] == 1) && (picture[j - 1, i + 1] != 1)) || ((picture[j + 1, i] * picture[j, i + 1] == 1) && (picture[j - 1, i - 1] != 1)) || //Небольшая модификцаия алгоритма для ещё большего утоньшения ((picture[j, i + 1] * picture[j - 1, i] == 1) && (picture[j + 1, i - 1] != 1)) || ((picture[j, i - 1] * picture[j - 1, i] == 1) && (picture[j + 1, i + 1] != 1)))) { picture[j, i] = 0; } } } for (int i = 0; i < picture.GetLength(1); i++) { for (int j = 0; j < picture.GetLength(0); j++) { // picture[j, i] = picture[j, i] == 0 ? 255 : 0; if (0 == picture[j, i]) { picture[j, i] = 255; } else { picture[j, i] = 0; } } } Byte[,] outPicture = new Byte[newPicture.GetLength(0), newPicture.GetLength(1)]; for (int i = 0; i < newPicture.GetLength(1); i++) { for (int j = 0; j < newPicture.GetLength(0); j++) { outPicture[j, i] = picture[j + 1, i + 1]; } } return outPicture; } /// <summary> /// 全局阈值图像二值化 /// </summary> /// <param name="bmp">原始图像</param> /// <param name="method">二值化方法</param> /// <param name="threshold">输出:全局阈值</param> /// <returns>二值化后的图像数组</returns> public static Byte[,] ToBinaryArray(this Bitmap bmp, out Int32 threshold) { // 位图转换为灰度数组 Byte[,] GrayArray = bmp.ToGrayArray(); // 计算全局阈值 threshold = OtsuThreshold(GrayArray); // 根据阈值进行二值化 Int32 PixelHeight = bmp.Height; Int32 PixelWidth = bmp.Width; Byte[,] BinaryArray = new Byte[PixelHeight, PixelWidth]; for (Int32 i = 0; i < PixelHeight; i++) { for (Int32 j = 0; j < PixelWidth; j++) { BinaryArray[i, j] = Convert.ToByte((GrayArray[i, j] > threshold) ? 255 : 0); } } return BinaryArray; } /// <summary> /// 将位图转换为灰度数组(256级灰度) /// </summary> /// <param name="bmp">原始位图</param> /// <returns>灰度数组</returns> public static Byte[,] ToGrayArray(this Bitmap bmp) { Int32 PixelHeight = bmp.Height; // 图像高度 Int32 PixelWidth = bmp.Width; // 图像宽度 Int32 Stride = ((PixelWidth * 3 + 3) >> 2) << 2; // 跨距宽度 Byte[] Pixels = new Byte[PixelHeight * Stride]; // 锁定位图到系统内存 BitmapData bmpData = bmp.LockBits(new Rectangle(0, 0, PixelWidth, PixelHeight), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb); Marshal.Copy(bmpData.Scan0, Pixels, 0, Pixels.Length); // 从非托管内存拷贝数据到托管内存 bmp.UnlockBits(bmpData); // 从系统内存解锁位图 // 将像素数据转换为灰度数组 Byte[,] GrayArray = new Byte[PixelHeight, PixelWidth]; for (Int32 i = 0; i < PixelHeight; i++) { Int32 Index = i * Stride; for (Int32 j = 0; j < PixelWidth; j++) { GrayArray[i, j] = Convert.ToByte((Pixels[Index + 2] * 19595 + Pixels[Index + 1] * 38469 + Pixels[Index] * 7471 + 32768) >> 16); Index += 3; } } return GrayArray; } /// <summary> /// 大津法计算阈值 /// </summary> /// <param name="grayArray">灰度数组</param> /// <returns>二值化阈值</returns> public static Int32 OtsuThreshold(Byte[,] grayArray) { // 建立统计直方图 Int32[] Histogram = new Int32[256]; Array.Clear(Histogram, 0, 256); // 初始化 foreach (Byte b in grayArray) { Histogram[b]++; // 统计直方图 } // 总的质量矩和图像点数 Int32 SumC = grayArray.Length; // 总的图像点数 Double SumU = 0; // 双精度避免方差运算中数据溢出 for (Int32 i = 1; i < 256; i++) { SumU += i * Histogram[i]; // 总的质量矩 } // 灰度区间 Int32 MinGrayLevel = Array.FindIndex(Histogram, NonZero); // 最小灰度值 Int32 MaxGrayLevel = Array.FindLastIndex(Histogram, NonZero); // 最大灰度值 // 计算最大类间方差 Int32 Threshold = MinGrayLevel; Double MaxVariance = 0.0; // 初始最大方差 Double U0 = 0; // 初始目标质量矩 Int32 C0 = 0; // 初始目标点数 for (Int32 i = MinGrayLevel; i < MaxGrayLevel; i++) { if (Histogram[i] == 0) continue; // 目标的质量矩和点数 U0 += i * Histogram[i]; C0 += Histogram[i]; // 计算目标和背景的类间方差 Double Diference = U0 * SumC - SumU * C0; Double Variance = Diference * Diference / C0 / (SumC - C0); // 方差 if (Variance > MaxVariance) { MaxVariance = Variance; Threshold = i; } } // 返回类间方差最大阈值 return Threshold; } /// <summary> /// 检测非零值 /// </summary> /// <param name="value">要检测的数值</param> /// <returns> /// true:非零 /// false:零 /// </returns> private static Boolean NonZero(Int32 value) { return (value != 0) ? true : false; } /// <summary> /// 将二值化数组转换为二值化图像 /// </summary> /// <param name="binaryArray">二值化数组</param> /// <returns>二值化图像</returns> public static Bitmap BinaryArrayToBinaryBitmap(Byte[,] binaryArray) { // 将二值化数组转换为二值化数据 Int32 PixelHeight = binaryArray.GetLength(0); Int32 PixelWidth = binaryArray.GetLength(1); Int32 Stride = ((PixelWidth + 31) >> 5) << 2; Byte[] Pixels = new Byte[PixelHeight * Stride]; for (Int32 i = 0; i < PixelHeight; i++) { Int32 Base = i * Stride; for (Int32 j = 0; j < PixelWidth; j++) { if (binaryArray[i, j] != 0) { Pixels[Base + (j >> 3)] |= Convert.ToByte(0x80 >> (j & 0x7)); } } } // 创建黑白图像 Bitmap BinaryBmp = new Bitmap(PixelWidth, PixelHeight, PixelFormat.Format1bppIndexed); // 设置调色表 ColorPalette cp = BinaryBmp.Palette; cp.Entries[0] = Color.Black; // 黑色 cp.Entries[1] = Color.White; // 白色 BinaryBmp.Palette = cp; // 设置位图图像特性 BitmapData BinaryBmpData = BinaryBmp.LockBits(new Rectangle(0, 0, PixelWidth, PixelHeight), ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed); Marshal.Copy(Pixels, 0, BinaryBmpData.Scan0, Pixels.Length); BinaryBmp.UnlockBits(BinaryBmpData); return BinaryBmp; } } } |
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