bitmap的图像像素遍历方法

public class FastBitmap
{
    BitmapData bitmapData;
    public FastBitmap(Bitmap bitmap)
    {
        this.bitmapData=bitmap.LockBits(new Rectangle(,,bitmap.Width,bitmap.Height), System.Drawing.Imaging.ImageLockMode.ReadWrite, bitmap.PixelFormat);
    }
    public unsafe Color GetPixel(int x,int y)
    {
        if (bitmapData.PixelFormat == PixelFormat.Format32bppRgb || bitmapData.PixelFormat == PixelFormat.Format32bppArgb)
        {
            byte* numPtr = (byte*)((int)bitmapData.Scan0 + y * bitmapData.Stride + x * );
            return Color.FromArgb(numPtr[],numPtr[], numPtr[],numPtr[]);
        }
        if (bitmapData.PixelFormat == PixelFormat.Format24bppRgb)
        {
            byte* numPtr2 = (byte*)((int)bitmapData.Scan0 + y * bitmapData.Stride + x * );
            return Color.FromArgb(numPtr2[], numPtr2[], numPtr2[]);
        }
        return Color.Empty;
    }
}