I am working on undergraduate project to find the number of empty slots in parking area using image processing. I have done individual color extraction what should be my next step

i have done the code from image acquisition of the image till the part of extracting individual components of RGB now what should be my next step? my code is as follows:

%For the demo purpose currently we have used the sample images from the %Internet and so imread command is used in this case.

back_img=imread('C:\Users\Anwar\Desktop\emptyPark.jpg'); car_img=imread('C:\Users\Anwar\Desktop\CarPark.jpg');

%Extracting the individual Red,Green and Blue color channels. redChannel=car_img(:,:,1); greenChannel=car_img(:,:,2); blueChannel=car_img(:,:,3);

for this project i have also referred to some previously answered question attaching the link as well: https://in.mathworks.com/matlabcentral/answers/126413-how-to-detect-free-spots-in-a-parking-area