Calculate activity level base on differenceImage() in JMyron

The code below use the function differenceImage in JMyron to calculate activity level.

(Skeleton based on Rijk's contriubution)

import JMyron.*;

JMyron m;//a camera object

int numPixels;


void setup(){
  size(320,240);
  m = new JMyron();//make a new instance of the object
  m.start(width,height);//start a capture at 320x240

//  m.findGlobs(0);//disable the intelligence to speed up frame rate
  println("Myron " + m.version()); 
  numPixels = width * height;
  // Create an array to store the previously captured frame
  previousFrame = new int[numPixels];
  currentFrame=new int[numPixels];
//  m.adaptivity(0.5);
}


void draw(){
  //count of non-black image (base on the differenceImage array)
    int nonBlackCount=0;
  m.update();//update the camera view
  loadPixels();
  int[] diffFrame = m.differenceImage(); //get the current image of the camera
  for (int i=0; i<diffFrame.length; i++){
    pixels[i]=diffFrame[i];
    if((red(diffFrame[i])!=0)&&(green(diffFrame[i])!=0)&&(blue(diffFrame[i]))!=0){
      nonBlackCount++;
    }
  }
}


void mousePressed(){
}

public void stop(){
  m.stop();//stop the object
  super.stop();
}