Programmatically trigger Screenshot

[DllImport("user32.dll")]
static extern int SendMessage(IntPtr hWnd, int Msg, uint wParam, uint lParam);
[DllImport("user32.dll")]
static extern IntPtr GetActiveWindow();
...
IntPtr hWnd = GetActiveWindow();
SendMessage(hWnd, 0x0100 /*WM_KEYDOWN*/, 0x2C /*VK_SNAPSHOT*/, 0);
SendMessage(hWnd, 0x0101 /*WM_KEYUP*/, 0x2C /*VK_SNAPSHOT*/, 0);

            if (e.KeyCode == Keys.H)
            {

                GTA.Script.Wait(2000);
                Game.Pause(true);
                SendKeys.Send("{PRTSC}"); //Take Picture without modified ReShade shader
                SendKeys.Send("{PGDN}");  //Toggle to preselected ReShade shader
                SendKeys.Send("{PRTSC}"); //Take Picture with additional shader
                SendKeys.Send("{PGDN}");  //Toggle back
                Game.Pause(false);

            }