function setup() {

  createCanvas(640, 480);

  capture = createCapture(VIDEO);

  capture.size(100, 480);

  capture.hide();

}

​

function draw() {

  background(0);

  capture.loadPixels();

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

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

      let ind = (x + y * capture.width) * 4;

      let r = capture.pixels[ind + 0]; //R

      let g = capture.pixels[ind + 1]; //G

      let b = capture.pixels[ind + 2]; //B

      let bright = (r + g + b) / 3;

      if (bright < 128) {

        capture.pixels[ind + 0] = 0; //R

        capture.pixels[ind + 1] = 0; //G

        capture.pixels[ind + 2] = 0; //B

      } else {

        capture.pixels[ind + 0] = 255; //R

        capture.pixels[ind + 1] = 255; //G

        capture.pixels[ind + 2] = 255; //B

      }

    }

  }

​

  capture.updatePixels();

  image(capture, 0, 0, width, height);

}

​