win32gui How to capture window that is currently not visible or hiden?

Question

capture_specific_window retures screenshot of very front window when the window is covered by it.

import win32gui
import numpy as np
import cv2
import pyautogui

def capture_specific_window(window_name):
    hwnd = win32gui.FindWindow(None, window_name)
    if not hwnd:
        raise Exception('Window not found: ' + window_name)

    left, top, right, bot = win32gui.GetClientRect(hwnd)
    x, y = win32gui.ClientToScreen(hwnd, (left, top))
    return cv2.cvtColor(
        np.asarray(
            pyautogui.screenshot(
                region=(x, y,
                        *win32gui.ClientToScreen(hwnd, (right - x, bot - y))))), cv2.COLOR_RGB2BGR)