PImage miImagen;

color colorPixel;

int anchoPixel;
int altoPixel;

void setup(){
  size(500, 500, P3D);
  miImagen = loadImage("VanGogh-self-portrait-dedicated_to_gaugin.jpg");
}

void draw(){
  background(255);
  
  anchoPixel = int(map(mouseX, 0, width, 4, width));
  altoPixel = int(map(mouseY, 0, height, 4, height));
  
  miImagen.loadPixels();
  for(int i=0;i<miImagen.width;i+=anchoPixel){
    for(int j=0;j<miImagen.height;j+=altoPixel){
      colorPixel = miImagen.get(i,j);
      fill(colorPixel);
      noStroke();
      
      rect(i, j, anchoPixel, altoPixel);
    }
  }
}