let slider;

​

​

function setup() { 

  createCanvas(400, 400);

  video = createCapture(VIDEO);

  video.size(400, 400);

  noStroke();

  slider = createSlider(3,100,25)

  slider.position(10, 10)

}

function draw() { 

  background(0);

  video.loadPixels();

  let stepSize = slider.value();

  for (let x = 0; x < video.width; x += stepSize) {

    for (let y = 0; y < video.height; y += stepSize) {

      let index = ((y*video.width) + x) * 4;

      let r = video.pixels[index];

      let g = video.pixels[index + 1];

      let b = video.pixels[index + 2];

      fill(r/2, g, b/2);

      rect(x, y, stepSize, stepSize);

    }

  }

}

​