private void Init()
{
_windowDC = User.GetWindowDC(_windowHandle); // hdcSys
_compatDC = Gdi.CreateCompatibleDC(_windowDC); // hdcMem
BITMAPINFO bi = new BITMAPINFO();
bi.bmiHeader.Init();
bi.bmiHeader.biWidth = _rc.Width;
bi.bmiHeader.biHeight = -_rc.Height;
bi.bmiHeader.biPlanes = 1;
bi.bmiHeader.biBitCount = 32;
_bitmap = Gdi.CreateDIBSection(_windowDC, ref bi, DIBColors.DIB_RGB_COLORS, out _bitmapPixels, IntPtr.Zero, 0);
IntPtr hOldBmp = Gdi.SelectObject(_compatDC, _bitmap);
Gdi.DeleteObject(hOldBmp);
_mat = new Image <Bgra, byte>(_rc.Width, _rc.Height, 0, _bitmapPixels);
}