Parking Counter System

To develop a image processing program in which a video feed of a parking lot is provided to the program and the program counts the number of cars in the parking lot from the number of available spaces iteratively. So if in the video 3 cars come in the parking lot, the count adds up to +3 and similarly if 2 cars go out of the parking lot the count goes to 3 - 2 = 1. So we can either do this by continuously evaluting the video feed or pick up an image from the video in every 5 seconds( or Some time frame) and apply image processing to it and count the number of cars and vehicles out of the total parking spots.