I want to make the pixels of frame differencing becomes transparent. The following program can turn the pixels with differencing become red in color. I want to turn it into transparent, so that I can see another image imgBG covered by this theMov.image(), how can I do this? I want do something when tracking people move, the part of pixels can become transparent, and see the imgBG. Please help.


PImage imgBG;
import JMyron.*;

JMyron theMov;
int[] currFrame;
int[] prevFrame;
int tolerance;
boolean revealing;


void setup() {
 size(640, 480);
imgBG = loadImage("2.jpg");
 theMov = new JMyron();
 theMov.start(width, height);
 theMov.findGlobs(0);
 
 // initialize the pixel arrays to avoid a NullPointerException
 loadPixels();
 currFrame = prevFrame = pixels;

 tolerance = 40;  
 revealing = true;
 
 
}

void draw() {
image(imgBG,0,0);  
 background(0);

 theMov.update();
 // save the last frame before updating it
 prevFrame = currFrame;
 currFrame = theMov.image();

 // draw each pixel to the screen only if its change factor is
 // higher than the tolerance value
 
 float r,g,b;
 loadPixels();
 for (int i=0; i < width*height; i++) {
   if (comparePixels(i)) {

     //pixels[i] = currFrame[i];
     pixels[i] = color(255,0,0);
     
   }
 }
 updatePixels();
}

boolean comparePixels(int index) {
 if (Math.abs(red(currFrame[index])-red(prevFrame[index])) < tolerance)
   if (Math.abs(green(currFrame[index])-green(prevFrame[index])) < tolerance)
     if (Math.abs(blue(currFrame[index])-blue(prevFrame[index])) < tolerance)
       return !revealing;

 return revealing;
}

void keyReleased() {
 if (key == '.' || key == '>') {
   // increase tolerance
   tolerance += 2;
 } else if (key == ',' || key == '<') {
   // decrease tolerance
   tolerance -= 2;

 // toggle the revealing mode
 } else if (key == ' ') {
   revealing = !revealing;
 }
}

public void stop() {
 theMov.stop();
 super.stop();
}