​

function preload() {

  cat= loadImage("cat.jpg");

}

​

function setup(){

  createCanvas(480, 270);

  pixelDensity(1);

  cat.loadPixels();

  //Make every other pixel green.

  for (let x=0; x<width; x++){

    for(let y=0; y<height; y++){

      var index=(x+y*width)*8;

      cat.pixels[index]=0;

      cat.pixels[index+1]=255;

      cat.pixels[index+2]=0;

      cat.pixels[index+3]=255;

    }

  }

  //Erase a line that is 10 pixels tall across the middle of it.

   for (let y=height/2-5;y<height/2+5;y++){

    for (let i=0;i<width;i++){ 

      cat.set(i,y,[0,0,0,0]);

    }

  }

  //Turn a line that is 10 pixels wide down the middle of it blue.

   for (let y=width/2-5;y<width/2+5;y++){

    for (let i=0;i<height;i++){ 

      cat.set(y,i,[0,0,255,255]);

    }

  }

  cat.updatePixels();

}

​

function draw(){

  background(50);

  image(cat,0,0);

}