Face Detection

Here is an example that illustrates how to detect faces in a live video stream.

Load cascade file

xml_file = fullfile(mexopencv.root(),'test','haarcascade_frontalface_alt2.xml');
classifier = cv.CascadeClassifier(xml_file);

Set up camera

camera = createVideoCapture([], 'lena');
pause(2); % Necessary in some environment. See help cv.VideoCapture
assert(camera.isOpened(), 'Camera failed to initialize');

disp('Face detection demo. Press any key when done.');

Face detection demo. Press any key when done.

Set up display window, and start the main loop

window = figure('KeyPressFcn',@(o,e) setappdata(o,'flag',true));
setappdata(window, 'flag',false);

% Start main loop
while ishghandle(window)
    % Grab and preprocess an image
    im = camera.read();
    if isempty(im), break; end
    im = cv.resize(im, 0.5, 0.5);
    gr = cv.cvtColor(im, 'RGB2GRAY');
    gr = cv.equalizeHist(gr);

    % Detect faces
    boxes = classifier.detect(gr, 'ScaleFactor',1.3,...
        'MinNeighbors',2, 'MinSize',[30,30]);

    % Draw results
    imshow(im);
    for i = 1:numel(boxes)
        rectangle('Position',boxes{i}, 'EdgeColor','g', 'LineWidth',2);
    end

    % Terminate if any user input
    flag = getappdata(window, 'flag');
    if isempty(flag) || flag, break; end
    pause(0.1);
end

% Close
camera.release();