how to label the vacant space

this is my coding that i have created..

I=imread('park2.jpg');
imshow(I);
gray=rgb2gray(I);
imshow(gray);

Binary = I;
BW = im2bw(Binary, graythresh(Binary));
BW = ~BW;
figure, imshow(BW)

L = bwlabel(BW);
s = regionprops(L, 'Centroid');
imshow(BW)
hold on
for k = 1:numel(s)
    c = s(k).Centroid;
    text(c(1), c(2), sprintf('%d', k), ...
        'HorizontalAlignment', 'center', ...
        'VerticalAlignment', 'middle');
end
hold off

however,the label is not right.. i want to label the vacant space only and want to display the output of vacant space.. this is how it goes http://s17.postimage.org/wimc8cbzz/parking.jpg

please help me solve this

[Syazwan]

please...can anyone help me with this problem..:(

Answer 1

[Geoff]

I wouldn't use regionprops here. That just connects pixels. You can't guarantee that will have anything to do with empty parking spaces in a thresholded image.

The first thing I would do is work out where the car parks are. I would do this manually if it's a fixed camera, but if I had to detect it I might try a hough transform looking for evenly-spaced groups of parallel lines. The point is that I would expect a certain structure - I wouldn't just go in blind, expecting the most basic of image processing techniques to work. Because in my opinion there is no real-world application for a totally automatic and calibration-free parking vacancy system.

Once I had a bounding rectangle for each park, I'd then look at all the pixels in each parking rectangle (or quad, if I expected any nontrivial camera rotation) and make the call on whether I think there's a car in that rectangle or not. To do that I would have heuristics relating to the size and shape (and colour) of pixel blobs, as well as their density and distribution within the rectangle. For example, if a person or shopping trolley was sitting in a vacant space, I might not want to detect it as a car.

[Syazwan]

actually,i want to display how many vacancy are left in numbers after detected the space..

[Walter Roberson]

Go ahead. Geoff's answer gives you a framework to proceed to locate the areas, after which you can count them.

[Syazwan]

could you guys give me a sample coding or example because i am new in this matlab world..

if there is an example,i can make it as my reference..

by the way,thank a lot for gave me some advice...

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/8026-best-way-s-to-master-matlab