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;
            }
        }


    }