Rewrite variable every n times

[andrea0913]

I'm doing image processing with cv2, and i need to replace the background every 30 seconds during 2 minutes. The background will be something like a photo of the current chroma.

def Foto():
    cv2.imwrite("Fondo1.jpg",entrada4)
    entrada = cv2.imread("Fondo1.jpg")

....


t = threading.Timer(3.0,Foto)
t.start()

I think the problem is i'm defining "entrada" at the begining of my code but also defining "entrada" in the funtion Foto()

entrada = cv2.imread("Fondo.jpg")

def Foto():
    cv2.imwrite("Fondo1.jpg",entrada4)
    entrada = cv2.imread("Fondo1.jpg")
....
t = threading.Timer(3.0,Foto)
t.start()

I need every 30 seconds it rewrites the image "fondo1" and replace "entrada" with that image. Like taking a photo of what the chroma is showing and change the background witht the photo.