Win8Metro(C#)数字图像处理--2.40二值图像轮廓提取

http://dongtingyueh.blog.163.com/blog/static/4619453201271481335630/

[函数名称]

二值图像轮廓提取 ContourExtraction(WriteableBitmap src)

[算法说明]

二值图像的轮廓提取对于图像识别，图像分割有着重要意义。该算法的核心就是将图像目标的内部点消除。所谓内部点，我们要根据当前像素点的邻域来进行判断，假设邻域窗口为3*3窗口，如果当前像素P(x,y)的八个邻域像素满足如下条件，则该点即内部点：

1，P(x,y)为目标像素，假设目标像素为黑色0，背景像素为白色255，那么P(x,y)=0;

2，P(x,y)的八个邻域像素均为目标像素0；

我们把满足条件的内部点删除，换为背景点255，即可得到图像轮廓。

内部点如下图所示：



[函数代码]

/// <summary>

/// Contour Extraction process.

/// </summary>

/// <param name="src">The source image.</param>

/// <returns></returns>

public static WriteableBitmap ContourExtraction(WriteableBitmap src)

{

if (src != null)

{

int w = src.PixelWidth;

int h = src.PixelHeight;

WriteableBitmap dilationImage = new WriteableBitmap(w, h);

byte[] temp = src.PixelBuffer.ToArray();

byte[] tempMask = (byte[])temp.Clone();

for (int j = 1; j < h-1; j++)

{

for (int i = 4; i < w*4-4; i+=4)

{

if ((tempMask[i + j * w * 4] == 0) && (tempMask[i - 4 + j * w * 4] == 0) && (tempMask[i + 4 + j * w * 4] == 0) && (tempMask[i - 4 + (j - 1) * w * 4] == 0)

&& (tempMask[i - 4 + (j + 1) * w * 4] == 0) && (tempMask[i + (j - 1) * w * 4] == 0) && (tempMask[i + (j + 1) * w * 4] == 0)

&& (tempMask[i + 4 + (j - 1) * w * 4] == 0) && (tempMask[i + 4 + (j + 1) * w * 4] == 0))

{

temp[i + j * w * 4] = (byte)255;

temp[i + 1 + j * w * 4] = (byte)255;

temp[i + 2 + j * w * 4] = (byte)255;

}

}

}

Stream sTemp = dilationImage.PixelBuffer.AsStream();

sTemp.Seek(0, SeekOrigin.Begin);

sTemp.Write(temp, 0, w * 4 * h);

return dilationImage;

}

else

{

return null;

}

}

[图像效果]