Incorrect output in image processing.

I have a code which is counting the number of empty parking slots. The method used is background subtraction, but I am getting incorrect output. close all; set(0,'DefaultFigureWindowStyle','docked') %dock the figures base_dir = 'C:\Users\USER\Desktop\final year project'; cd(base_dir);

%% get listing of frames f_list = dir('*jpg');

%% make average of background images N = 4; % num of frames to use to make averaged background tps=10; status = [0 0 0 0 0 0 0 0 0 0]; img = zeros(960,540,N); for i = 1:N img_tmp = imread(f_list(i).name); img(:,:,i) = img_tmp(:,:,1); %img(:,:,i) = rgb2gray(img_tmp); end bck_img = (mean(img,3)); %average background template %subplot(121);imagesc(bck_img) %subplot(122);imagesc(img(:,:,1)) clear img; pause(5) %gaussian filter hsize = 80; sigma = 20; gaus_filt = fspecial('gaussian',hsize , sigma); %gaus_filt = fspecial('log',hsize , sigma); %subplot(121); imagesc(gaus_filt) %subplot(122); mesh(gaus_filt) colormap(gray)

SE = strel('diamond', 0); %this makes a matrice object for passing into imdilate())

%% Operations on frames

for i = N:1:length(f_list)

    img_tmp = double(imread(f_list(i).name)); %load image and convert to double for computation 
    img = img_tmp(:,:,1); %reduce to just the first dimension
    %img = rgb2gray(img_tmp)
    subplot(221);imagesc(img);
    title('Raw');

    %subtract background from the image
    sub_img = (img - bck_img);
    subplot(222);imagesc(sub_img);
    title('background subtracted');

    %gaussian blurr the image
    gaus_img = filter2(gaus_filt,sub_img,'same');     
    subplot(223);imagesc(gaus_img);
    title('gaussian smoothed');

    %threshold the image
    subplot(224);hist(gaus_img(:));
    thres_img = (gaus_img < 10);
    thres_img = ~thres_img;
    thres_img = bwareaopen(thres_img,10);
    se2 = strel('disk',1);        
    thres_img = imerode(thres_img,se2);
    %counting no of blobs
    [L, num] = bwlabel(thres_img);
    stats = regionprops(L, 'Centroid');
    thres_img = ~thres_img;

    subplot(224);imagesc(thres_img);
    %subplot(224);imagesc(gaus_img);
    title('thresholded');

    clc
    fprintf('Total parking spaces  :  %i\n',tps)
    fprintf('filled parking spaces :  %i\n',num)
    fprintf('vacant parking spaces :  %i\n',tps-num)
    fprintf('coordinates :\n')

    for x=1:1:num
        fprintf('point %i : %f , %f \n',x,stats(x,1).Centroid(1),stats(x,1).Centroid(2));
        for c=1:1:4
            if(stats(x,1).Centroid(1)>50+100*c && stats(x,1).Centroid(1)<150+100*c && stats(x,1).Centroid(2)>70 && stats(x,1).Centroid(2)<180 )
                status(c)=true;
            end
        end
        for c=4:1:tps
            if(stats(x,1).Centroid(1)>50+100*(c-4) && stats(x,1).Centroid(1)<150+100*(c-4) && stats(x,1).Centroid(2)>350 && stats(x,1).Centroid(2)<470 )
                status(c)=true;
            end
        end
     end
    %disp(status);
    fprintf('\nOccupied slots : ')
    for c=1:1:10
    if(status(c)==1)
        fprintf(' %i ',c);
    end
    end
    status = [0 0 0 0 0 0 0 0 0 0];
    pause(.001)
end
I don't know how to proceed futher and what is wrong with the code.

[Image Analyst]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

http://www.mathworks.com/matlabcentral/answers/13205#answer_18099