如何使用C#去灰度化一幅图像

灰度化一幅图像就是将图像的色彩信息全部丢掉,将24位的位图信息,用8位来表示,灰度图共有256级灰度等级,也就是将24位位图的一点如(255,255,255)转换成255,所以R,G,B三个值所乘的系数和为1
用伪语句可以表示如下

public bitmap GrayScal(bitmap orgbmp)
{
建立一个与原图片等大的8位的图片
取出原图像中的每一个点
新图像的点=原图像点的红色量*系数1+绿色量*系数2+黄色量*系统3
返回新图像
}

/// <summary>
/// 对图像进行点运算,
/// </summary>
public class PointTrans
{
private readonly double cb;
private readonly double cg;
private readonly double cr;

/// <summary>
/// 做点运算,要给每一个偏量,做一下设置,比如做图像的灰度图就需要现设置
/// </summary>
/// <param name="cr"></param>
/// <param name="cg"></param>
/// <param name="cb"></param>
public PointTrans(double cr, double cg, double cb)
{
this.cr = cr;
this.cg = cg;
this.cb = cb;
}

public  Bitmap GrayScaleBmp(Bitmap orgData)
{
int bmpWidth = orgData.Width, bmpHeight = orgData.Height;
Bitmap destData = ImageTools.CreateGrayscaleImage(bmpWidth, bmpHeight);
Rectangle bmpRect=new Rectangle(0,0,bmpWidth,bmpHeight);

BitmapData orgBmpData = orgData.LockBits(bmpRect, ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);

BitmapData destBmpData = destData.LockBits(bmpRect, ImageLockMode.WriteOnly, PixelFormat.Format8bppIndexed);
ProcessFilter(orgBmpData,destBmpData);

orgData.UnlockBits(orgBmpData);
destData.UnlockBits(destBmpData);
return destData;

}

protected unsafe void ProcessFilter(BitmapData sourceData, BitmapData destinationData)
{
// get width and height
int width = sourceData.Width;
int height = sourceData.Height;

int srcOffset = sourceData.Stride - width*3;
int dstOffset = destinationData.Stride - width;

// do the job
byte* src = (byte*) sourceData.Scan0.ToPointer();
byte* dst = (byte*) destinationData.Scan0.ToPointer();

// for each line
for (int y = 0; y < height; y++)
{
// for each pixel
for (int x = 0; x < width; x++, src += 3, dst++)
{
*dst = (byte) (cr*src[RGB.R] + cg*src[RGB.G] + cb*src[RGB.B]);
}
src += srcOffset;
dst += dstOffset;
}
}

}