如果有一种更快的方式我很想知道！

const int WIDTH = /* width */;
const int HEIGHT = /* height */;


Bitmap bitmap = new Bitmap(WIDTH,HEIGHT,PixelFormat.Format32bppRgb);
Byte[] bytes = new byte[WIDTH * HEIGHT * 4];

BitmapToByteArray(bitmap,bytes);


private unsafe void BitmapToByteArray(Bitmap bitmap,Byte[] bytes)
{
    BitmapData bitmapData = bitmap.LockBits(new Rectangle(0,WIDTH,HEIGHT),ImageLockMode.ReadOnly,PixelFormat.Format32bppRgb);

    fixed(byte* pBytes = &bytes[0])
    {
        MoveMemory(pBytes,bitmapData.Scan0.ToPointer(),WIDTH * HEIGHT * 4);
    }

    bitmap.UnlockBits(bitmapData);
}

[DllImport("Kernel32.dll",EntryPoint = "RtlMoveMemory",SetLastError = false)]
private static unsafe extern void MoveMemory(void* dest,void* src,int size);