WPF：图像处理（二）灰度化(4)

        /// 位图灰度化 www.2cto.com  
        /// </summary> 
        /// <param name="bitmap">原始位图</param> 
        /// <returns>灰度位图</returns> 
        /// <remarks>扩展方法</remarks> 
        public static BitmapSource ToGrayBitmap(this BitmapSource bitmap) 
        {   // 将像素格式统一到Bgr32，并提取图像数据 
            Int32 PixelHeight = bitmap.PixelHeight; // 图像高度 
            Int32 PixelWidth = bitmap.PixelWidth;   // 图像宽度 
            Int32 Stride = PixelWidth << 2;         // 扫描行跨距 
            Byte[] Pixels = new Byte[PixelHeight * Stride]; 
            if (bitmap.Format == PixelFormats.Bgr32 || bitmap.Format == PixelFormats.Bgra32) 
            {   // 拷贝像素数据 
                bitmap.CopyPixels(Pixels, Stride, 0); 
            } 
            else 
            {   // 先进行像素格式转换，再拷贝像素数据 
                new FormatConvertedBitmap(bitmap, PixelFormats.Bgr32, null, 0).CopyPixels(Pixels, Stride, 0); 
            } 
 
            // 将像素数据转换为灰度数据 
            Int32 GrayStride = ((PixelWidth + 3) >> 2) << 2; 
            Byte[] GrayPixels = new Byte[PixelHeight * GrayStride]; 
            for (Int32 i = 0; i < PixelHeight; i++) 
            { 
                for (Int32 j = 0; j < PixelWidth; j++) 
                {