PImage a;

void setup(){
  a = loadImage("zkm.jpg");
  size(446,397);
  
  stroke(100);
  background(255);
  smooth();rectMode(CENTER);
}

int x=0;
int y=0;

void draw(){ 
  float pointillize = 4;
 
  int loc = x + y*a.width;
  float r = red(a.get(x,y));
  float g = green(a.get(x,y));
  float b = blue(a.get(x,y));
  fill(r,g,b,255);
  rect(x,y,pointillize,pointillize);
  x=x+(int)pointillize;
  if (x>width){
    x=0;
    y=y+4;}
}