How can I store an object when using timer function?

I am trying to implement a real time foreground analysis system. I am using 'timer' function to call the foreground analysis function at a given period to achieve it. Since the foreground analysis function requires certain amount of images/frames to identify the foreground, the prior information needs to be stored. (I created an object using vision.ForegroundDetector and the prior information should be stored in this object.) I tried to store this object in 'userData' and let the callback function use/update it. However, the foreground detector didn't detect anything. I am guessing the 'UserData' cannot take an object data, but I am not sure. Can anyone help me solve the problem? Thanks.

The code of the timer function and image analysis function are attached below:

(vid is the video acquired by matlab image acquasition toolbox.)

TimerData=timer('TimerFcn',{@FrameRateDisplay,vid,se},'Period',1/NumberFrameDisplayPerSecond,'ExecutionMode','fixedRate','BusyMode','drop','UserData', foregroundDetector);

function [foregroundDetector] = FrameRateDisplay(obj,event,vid,se)
persistent IM;
persistent handlesRaw;
persistent handlesPlot;

trigger(vid);
IM=getdata(vid,1,'uint8');
foregroundDetector =  get(obj, 'UserData');

if isempty(handlesRaw)
   % Detect the foreground in the current video frame
   foreground = step(foregroundDetector, IM);

     % if first execution, we create the figure objects
     subplot(2,1,1);
     handlesRaw=imshow(IM);
     title('CurrentImage');

     subplot(2,1,2);
     handlesPlot=imshow(foreground);

     title('Foreground');
  else
     % We only update what is needed
     set(handlesRaw,'CData',IM);
     set(obj, 'UserData', foregroundDetector);
  end

Answer 1

[Walter Roberson]

If handlesRAW is not empty, you fail to step the foreground detector or update the foreground plot.