Win8 Metro(C#)数字图像处理--2.49Zhang二值图像细化算法
[函数名称]
二值图像细化算法 WriteableBitmap ThinningProcess(WriteableBitmap src)
[算法说明]
图像细化（Image Thinning），一般指二值图像的骨架化（Image Skeletonization）的一种操作运算。
所谓的细化就是经过一层层的剥离，从原来的图中去掉一些点，但仍要保持原来的形状，直到得到图
像的骨架。骨架，可以理解为图象的中轴。
细化算法有很多，我们这里介绍一种二值图像的快速细化算法—Zhang 细化算法，该算法是Zhang于
1984年提出。
算法过程如下：
1，设二值图像中0为背景，1为目标。目标像素的8邻域如下图所示：
/// <summary>
/// Zhang's fast thinning process for binary image.
/// </summary>
/// <param name="src">The source image.</param>
/// <returns></returns>
public static WriteableBitmap ThinningProcess(WriteableBitmap src)////二值图像细化(Zhang快速细化算法)
{
if (src != null)
{
int w = src.PixelWidth;
int h = src.PixelHeight;
WriteableBitmap srcImage = new WriteableBitmap(w, h);
byte[] temp = src.PixelBuffer.ToArray();
byte[] tempMask = (byte[])temp.Clone();
int[,] srcBytes = new int[w, h];
for (int j = 0; j < h; j++)
{
for (int i = 0; i < w ; i++)
{
srcBytes[i, j] = (tempMask[i * 4 + j * w * 4] * 0.114 + tempMask[i * 4 + 1 + j * w * 4] * 0.587 + tempMask[i * 4 + 2 + j * w * 4] * 0.299 < 128 ? 0 : 1);
}
}
Thinning(ref srcBytes, w, h);
for (int j = 0; j < h; j++)
{
for (int i = 0; i < w; i++)
{
temp[i * 4 + j * w * 4] = temp[i * 4 + 1 + j * w * 4] = temp[i * 4 + 2 + j * w * 4] = (byte)(srcBytes[i, j] * 255);
}
}
Stream sTemp = srcImage.PixelBuffer.AsStream();
sTemp.Seek(0, SeekOrigin.Begin);
sTemp.Write(temp, 0, w * 4 * h);
return srcImage;
}
else
{
return null;
}
}
private static void Thinning(ref int[,] srcBytes,int w,int h)
{
int[] srcTemp;
int countNumber;
do
{
countNumber = 0;
for (int y = 1; y < h - 1; y++)
{
for (int x = 1; x < w - 1; x++)
{
srcTemp = new int[9] { srcBytes[x, y], srcBytes[x - 1, y - 1], srcBytes[x, y - 1], srcBytes[x + 1, y - 1], srcBytes[x + 1, y], srcBytes[x + 1, y + 1], srcBytes[x, y + 1], srcBytes[x - 1, y + 1], srcBytes[x - 1, y] };
if (srcBytes[x, y] != 1)
{
if (CountN(srcTemp) >= 2 && CountN(srcTemp) <= 6)
{
if (CountT(srcTemp) == 1)
{
if (srcBytes[x, y - 1] * srcBytes[x + 1, y] * srcBytes[x, y + 1] == 0)
{
if (srcBytes[x - 1, y] * srcBytes[x + 1, y] * srcBytes[x, y + 1] == 0)
{
srcBytes[x, y] = (byte)1;
countNumber++;
}
}
else
{
if (srcBytes[x, y - 1] * srcBytes[x + 1, y] * srcBytes[x - 1, y] == 0)
{
if (srcBytes[x, y - 1] * srcBytes[x, y + 1] * srcBytes[x - 1, y] == 0)
{
srcBytes[x, y] = (byte)1;
countNumber++;
}
}
}
}
}
}
}
}
} while (countNumber != 0);
}
private static int CountN(params int[] src)
{
int count = 0;
for (int i = 0; i < src.Length; i++)
{
if (src[i] == 0)
{
count++;
}
}
return count;
}
private static int CountT(params int[] src)
{
int count = 0;
for (int i = 1; i < src.Length; i++)
{
if (src[i] == 1 && src[i - 1] == 0)
{
count++;
}
}
if (src[src.Length - 1] == 0 && src[0] == 1)
{
count++;
}
return count;
}