急求4bit位图转化成24bit位图（彩色的）,该如何处理

急求4bit位图转化成24bit位图（彩色的）
本人初学c#关于图像处理方面的内容，请各位大神指教，这个程序为什么出来的图像结果总是不对？
public Bitmap ConvertToBitmap24(Bitmap bmp)
        {
            unsafe
            {
                int Width = bmp.Width;
                int Height = bmp.Height;
                Bitmap newbmp = new Bitmap(bmp.Width, bmp.Height, PixelFormat.Format24bppRgb);
                BitmapData data = new BitmapData();             
                BitmapData data2 = new BitmapData();
                newbmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb, data2);
                byte* bp2 = (byte*)data2.Scan0.ToPointer();
                int DestStride = Width;
                int stride = Width / 2; 
                int index=0;
                byte[] new4IndexBmpdataValues = GetBmp24BitColorValue(bmp); 
                for (int i = 0; i != Height; i++)
                {
                    for (int j = 0; j != Width; j++)
                    {                                
                        int index1 = (int)((byte)(new4IndexBmpdataValues[index] >> 4) & 0x0F);
                        int index2 = (int)(new4IndexBmpdataValues[index] & 0x0F);
                        bp2[i * DestStride + 3 * j] = cl[index1].B;
                        bp2[i * DestStride + 3 * j + 1] = cl[index1].G;
                        bp2[i * DestStride + 3 * j + 2] = cl[index1].R;
                        j++;
                        bp2[i * DestStride + 3 * j] = cl[index2].B;
                        bp2[i * DestStride + 3 * j + 1] = cl[index2].G;
                        bp2[i * DestStride + 3 * j + 2] = cl[index2].R;
                        index++;

                    }
                }
                newbmp.UnlockBits(data2);
                return newbmp;
            }
        }
        private static byte[] GetBmp24BitColorValue(Bitmap bmp)
        {

            int width = bmp.Width;
            int height = bmp.Height;
            Bitmap bitmap_oldCopy =bmp; 
             BitmapData oldcopyBmpdata = null;
            try
            {
                Rectangle rect = new Rectangle(0, 0, width, height);              
                oldcopyBmpdata = bitmap_oldCopy.LockBits(rect, ImageLockMode.ReadWrite, bitmap_oldCopy.PixelFormat);
                IntPtr ptrOldCopy = oldcopyBmpdata.Scan0;
                int oldBitmapDataLength = oldcopyBmpdata.Stride * height;              
                byte[] oldBmpValues = new byte[oldBitmapDataLength]; 
                System.Runtime.InteropServices.Marshal.Copy(ptrOldCopy, oldBmpValues, 0, oldBitmapDataLength);

                return oldBmpValues;
            }
            finally
            {
                if (oldcopyBmpdata != null)
                {
                    bitmap_oldCopy.UnlockBits(oldcopyBmpdata);
                }
            }
        }        
     

[解决办法]
这个我也没办法，等版主来帮楼主看下吧
[解决办法]
如果没有人愿意免费帮你搞定，本人可以有偿给你写这个代码。