Create a detector object.
faceDetector = vision.CascadeObjectDetector;
Read input image. 
   I = imread('visionteam.jpg');
Detect faces. 
   bboxes = step(faceDetector, I);
Annotate detected faces. 
  IFaces = insertObjectAnnotation(I, 'rectangle', bboxes, 'Face');
   figure, imshow(IFaces), title('Detected faces');