Capture Video and Save it using OpenCV Python

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cap = cv2.VideoCapture(0)
fourcc = cv2.VideoWriter_fourcc(*'XVID') # specify the codec
out=cv2.VideoWriter('output.avi',fourcc,20.0,(640,480))

while True:
    ret, frame = cap.read()
    cv2.imshow("frame", frame)
    out.write(frame)

    # exit video capture
    if cv2.waitKey(1) & 0xFF == ord("q"):
        break

cap.release()
out.release()
cv2.destroyAllWindows()

References
https://www.youtube.com/watch?v=Jvf5y21ZqtQ
https://github.com/mhdr/OpenCV/tree/master/002

Capture Video and make Grayscale using OpenCV Python

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import cv2
import numpy as np

cap = cv2.VideoCapture(0)

while True:
    ret, frame = cap.read()

    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    cv2.imshow("gray", gray)

    # exit video capture
    if cv2.waitKey(1) & 0xFF == ord("q"):
        break

cap.release()
cv2.destroyAllWindows()

References
https://www.youtube.com/watch?v=Jvf5y21ZqtQ
https://github.com/mhdr/OpenCV/tree/master/002

GUI automation in Python

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import pyautogui
screenWidth, screenHeight = pyautogui.size()
currentMouseX, currentMouseY = pyautogui.position()
pyautogui.moveTo(100, 150)
pyautogui.click()
pyautogui.moveRel(None, 10)  # move mouse 10 pixels down
pyautogui.doubleClick()
pyautogui.moveTo(500, 500, duration=2, tween=pyautogui.easeInOutQuad)  # use tweening/easing function to move mouse over 2 seconds.
pyautogui.typewrite('Hello world!', interval=0.25)  # type with quarter-second pause in between each key
pyautogui.press('esc')
pyautogui.keyDown('shift')
pyautogui.press(['left', 'left', 'left', 'left', 'left', 'left'])
pyautogui.keyUp('shift')
pyautogui.hotkey('ctrl', 'c')

References
https://pyautogui.readthedocs.io/en/latest/introduction.html

Get the height of Windows Taskbar using Python

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To get the work area size (desktop minus taskbar):

from win32api import GetMonitorInfo, MonitorFromPoint

monitor_info = GetMonitorInfo(MonitorFromPoint((0,0)))
work_area = monitor_info.get("Work")
print("The work area size is {}x{}.".format(work_area[2], work_area[3]))

To get the taskbar height:

from win32api import GetMonitorInfo, MonitorFromPoint

monitor_info = GetMonitorInfo(MonitorFromPoint((0,0)))
monitor_area = monitor_info.get("Monitor")
work_area = monitor_info.get("Work")
print("The taskbar height is {}.".format(monitor_area[3]-work_area[3]))

References
https://stackoverflow.com/questions/4357258/how-to-get-the-height-of-windows-taskbar-using-python-pyqt-win32/51602236

Extract differences between two images using OpenCV in Python

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import cv2
import numpy as np

img1 = cv2.imread("img1.png")
img2 = cv2.imread("img2.png")
diff = cv2.absdiff(img1, img2))
mask = cv2.cvtColor(diff, cv2.COLOR_BGR2GRAY)

th = 1
imask =  mask>th

canvas = np.zeros_like(img2, np.uint8)
canvas[imask] = img2[imask]

cv2.imwrite("result.png", canvas)

References
https://stackoverflow.com/questions/27035672/cv-extract-differences-between-two-images

Take Screenshot on Windows Using Python

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from PIL import ImageGrab
im = ImageGrab.grab()
im.save('screenshot.png')

Or

import win32gui, win32ui, win32con, win32api
hwin = win32gui.GetDesktopWindow()
width = win32api.GetSystemMetrics(win32con.SM_CXVIRTUALSCREEN)
height = win32api.GetSystemMetrics(win32con.SM_CYVIRTUALSCREEN)
left = win32api.GetSystemMetrics(win32con.SM_XVIRTUALSCREEN)
top = win32api.GetSystemMetrics(win32con.SM_YVIRTUALSCREEN)
hwindc = win32gui.GetWindowDC(hwin)
srcdc = win32ui.CreateDCFromHandle(hwindc)
memdc = srcdc.CreateCompatibleDC()
bmp = win32ui.CreateBitmap()
bmp.CreateCompatibleBitmap(srcdc, width, height)
memdc.SelectObject(bmp)
memdc.BitBlt((0, 0), (width, height), srcdc, (left, top), win32con.SRCCOPY)
bmp.SaveBitmapFile(memdc, 'screenshot.bmp')

Don’t forget to SetProcessDPIAware if necessary

import ctypes

user32 = ctypes.windll.user32
user32.SetProcessDPIAware()

References
https://stackoverflow.com/questions/4589206/python-windows-7-screenshot-without-pil