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.
*
* 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;
}
}
}
