(defun create-trackbar-example (&optional (camera-index 0) (width *default-width*)
                (height *default-height*))
  "Creates a trackbar and attaches it to the specified window.
   Move the slider to adjust the brightess of the camera output"
  (with-capture (capture (create-camera-capture camera-index))
    (let ((window-name "CREATE-TRACKBAR Example")
      (contrast (cffi:foreign-alloc :int :initial-contents '(50))))
      (set-capture-property capture +cap-prop-frame-width+ width)
      (set-capture-property capture +cap-prop-frame-height+ height)
      (named-window window-name)
      (move-window window-name 600 175)
      (do* ((frame (query-frame capture) (query-frame capture))
            (dest (clone-image frame))
            (scalar 0))
       ((plusp (wait-key *millis-per-frame*)) nil)
    (format t "Trackbar level:  ~a~%~%" (cffi:mem-ref contrast :int))
    (create-trackbar "Brightness" window-name contrast 100 (change-contrast contrast window-name frame dest))
    (setf scalar (scalar (- (cffi:mem-ref contrast :int 50))
                 (- (cffi:mem-ref contrast :int) 50)
                 (- (cffi:mem-ref contrast :int) 50)))
    (add-s frame scalar dest)
    (show-image window-name dest))
      (destroy-window window-name))))

(defun create-trackbar-example (&optional (camera-index 0) (width *default-width*)
                (height *default-height*))
  "Creates a trackbar and attaches it to the specified window.
   Move the slider to adjust the brightess of the camera output"
  (with-capture (capture (create-camera-capture camera-index))
    (let ((window-name "CREATE-TRACKBAR Example")
      (contrast (cffi:foreign-alloc :int :initial-contents '(50))))
      (set-capture-property capture +cap-prop-frame-width+ width)
      (set-capture-property capture +cap-prop-frame-height+ height)
      (named-window window-name)
      (move-window window-name 600 175)
      (do* ((frame (query-frame capture) (query-frame capture))
            (dest (clone-image frame))
            (scalar 0))
       ((plusp (wait-key *millis-per-frame*)) nil)
    (format t "Trackbar level:  ~a~%~%" (cffi:mem-ref contrast :int))
    (create-trackbar "Brightness" window-name contrast 100 (change-contrast contrast window-name frame dest))
    (setf scalar (scalar (- (cffi:mem-ref contrast :int 50))
                 (- (cffi:mem-ref contrast :int) 50)
                 (- (cffi:mem-ref contrast :int) 50)))
    (add-s frame scalar dest)
    (show-image window-name dest))
      (destroy-window window-name))))

(defun create-trackbar-example (&optional (camera-index 0) (width *default-width*)
                (height *default-height*))
  "Creates a trackbar and attaches it to the specified window.
   Move the slider to adjust the brightess of the camera output"
  (with-capture (capture (create-camera-capture camera-index))
    (let ((window-name "CREATE-TRACKBAR Example")
      (contrast (cffi:foreign-alloc :int :initial-contents '(50))))
      (set-capture-property capture +cap-prop-frame-width+ width)
      (set-capture-property capture +cap-prop-frame-height+ height)
      (named-window window-name)
      (move-window window-name 600 175)
      (do* ((frame (query-frame capture) (query-frame capture))
            (dest (clone-image frame))
            (scalar 0))
       ((plusp (wait-key *millis-per-frame*)) nil)
    (format t "Trackbar level:  ~a~%~%" (cffi:mem-ref contrast :int))
    (create-trackbar "Brightness" window-name contrast 100 (change-contrast contrast window-name frame dest))
    (setf scalar (scalar (- (cffi:mem-ref contrast :int 50))
                 (- (cffi:mem-ref contrast :int) 50)
                 (- (cffi:mem-ref contrast :int) 50)))
    (add-s frame scalar dest)
    (show-image window-name dest))
      (destroy-window window-name))))

(defun create-trackbar-example (&optional (camera-index 0) (width *default-width*)
                (height *default-height*))
  "Creates a trackbar and attaches it to the specified window.
   Move the slider to adjust the brightess of the camera output"
  (with-capture (capture (create-camera-capture camera-index))
    (let ((window-name "CREATE-TRACKBAR Example")
      (contrast (cffi:foreign-alloc :int :initial-contents '(50))))
      (set-capture-property capture +cap-prop-frame-width+ width)
      (set-capture-property capture +cap-prop-frame-height+ height)
      (named-window window-name)
      (move-window window-name 600 175)
      (do* ((frame (query-frame capture) (query-frame capture))
            (dest (clone-image frame))
            (scalar 0))
       ((plusp (wait-key *millis-per-frame*)) nil)
    (format t "Trackbar level:  ~a~%~%" (cffi:mem-ref contrast :int))
    (create-trackbar "Brightness" window-name contrast 100 (change-contrast contrast window-name frame dest))
    (setf scalar (scalar (- (cffi:mem-ref contrast :int 50))
                 (- (cffi:mem-ref contrast :int) 50)
                 (- (cffi:mem-ref contrast :int) 50)))
    (add-s frame scalar dest)
    (show-image window-name dest))
      (destroy-window window-name))))