Is it possible to restrict an object's motion by using a pixel value as a boarder?  In other words, if I have a white shape on a black background, can I tell processing something like

if ("pixel value is black") {
      velocity.x = -1*velocity.x;
      velocity.y = -1*velocity.y;
}

The image below is what I would like to use.  I have elements in motion using the following code, but I want to restrict the motion to occur within the swiggly shape (see image).




class Mover2 {

  PVector att5;
  PVector velocity;
  PVector location;
  float topSpeed;
  float xWidth;

  ////////////////this is the initialization of variables
  Mover2() {

    location = new PVector(random(width), random(height));
    velocity = new PVector(0,0);
    topSpeed = 30;
  }

  void update() {
    PVector att5att = new PVector (689, 64);
    PVector att5Dir = PVector.sub(att5att, location);
    att5Dir.mult(.0001);
    att5 = att5Dir;

    velocity.add(att5);
    velocity.limit(topSpeed);
    location.add(velocity);
  }

  void display() {
    noStroke();
    fill(0);
    ellipse(location.x, location.y, 2,2);
  }

  void checkEdges() {
    //-----this is not what I want to happen
    if(location.x > width) {
      velocity.x = -1*velocity.x;
    }
    if(location.x < 0) {
      velocity.x = -1*velocity.x;
    }
    if(location.y > height) {
      velocity.y = -1*velocity.y;
    }
    if(location.y < 0) {
      velocity.y = -1*velocity.y;
    }
  }
}

PImage img;
Mover2[] movers = new Mover2 [1000];


void setup() {
  size (1600, 100);
  img = loadImage("large elev outlines.png");
  for (int i = 0; i < movers.length; i++) {
    movers[i] = new Mover2();
  }
}

void draw () { 
  noStroke();
  fill(0,0,0);

  image (img, 0,0);

  for (int i = 0; i < movers.length; i++) {
    movers[i].update();
    movers[i].display();
    movers[i].checkEdges();
  }
}