PImage a;
int[] aPixels;
float signal;


void setup(){
  size(420,260);
  colorMode(RGB, width);
  aPixels = new int[width*height];
  a = loadImage("image1.jpg");
  for(int i=0; i<width*height; i++){
    aPixels[i] = a.pixels[i];
  }
}
  
void draw(){
  background(width-mouseX);
  for(int i=0; i<width*height; i++){
    if(brightness(a.pixels[i]) >= mouseX-2 && brightness(a.pixels[i]) <= mouseX+2){
      stroke(red(a.pixels[i]),green(a.pixels[i]),blue(a.pixels[i]),130);
      point(i%width, int(i/width));
    }
  }
}