how to detect a car entred parking lot and leaving it

source = videoinput('winvideo',1); thresh = 25; im=getsnapshot(source); %(Remove this) bg = im;

% read in 1st frame as background frame(change this) %

bg = imread('C:\Users\Aatif\Desktop\Thesis\A2.PNG');

bg_bw = rgb2gray(bg);

% convert background to greyscale %fg1 = bg_bw;

% ----------------------- set frame size variables ----------------------- %fr_size = size(bg);

width = size(bg_bw,2); height = size(bg_bw,1); fg = zeros(height, width);

% --------------------- process frames -----------------------------------

for i = 2:100

fr = getsnapshot(source); % read in frame

fr_bw = rgb2gray(fr); % convert frame to grayscale

fr_diff = abs(double(fr_bw) - double(bg_bw)); % cast operands as double to avoid negative overflow

for j=1:width % if fr_diff > thresh pixel in foreground

for k=1:height

if ((fr_diff(k,j) > thresh))

fg(k,j) = 1;

else

fg(k,j) = 0;

end

end

end

%bg_bw = fr_bw;

figure(1),subplot(2,1,1),imshow(fr)

%subplot(3,1,2),imshow(fr_bw)

subplot(2,1,2),imshow(fg)

M(i-1) = im2frame(uint8(fg),gray); % put frames into movie

if ((bg_bw) ~= (fr_bw))

textIn = ('Car has left the parking lot');

ha = actxserver('SAPI.SpVoice');

invoke(ha,'speak',textIn);

h = msgbox('Car has left the parking lot');

else

textIn = ('Car is in the parking lot');

ha = actxserver('SAPI.SpVoice');

invoke(ha,'speak',textIn);

h = msgbox('Car is in the the parking lot');

end

end

above is my code

i cant read if statment

its just reading else statment

can please some on help to solve this issue