import processing.video.*;
  
  // Size of each cell in the grid
  int cellSize = 15;
  // Number of columns and rows in our system
  int cols, rows;
  // Variable for capture device
  Capture video;
  
  void setup() {
    size(630, 480, P3D);
    //set up columns and rows
    cols = width / cellSize;
    rows = height / cellSize;
    colorMode(RGB, 255, 255, 255, 100);
    rectMode(CENTER);
  
    // Uses the default video input, see the reference if this causes an error
    video = new Capture(this, width, height, 15);
  
    background(0);
  }
  
  void draw() { 
    if (video.available()) {
      video.read();
      video.loadPixels();
      
      background(0, 0, 255);
  
      // Begin loop for columns
      for (int i = 0; i < cols;i++) {
        // Begin loop for rows
        for (int j = 0; j < rows;j++) {
  
          // Where are we, pixel-wise?
          int x = i * cellSize;
          int y = j * cellSize;
          int loc = (video.width - x - 1) + y*video.width; // Reversing x to mirror the image
  
          // Each rect is colored white with a size determined by brightness
          color c = video.pixels[loc];
          float sz = (brightness(c) / 255.0) * cellSize;
          fill(255);
          noStroke();
          rect(x + cellSize/2, y + cellSize/2, sz, sz);
        }
      }
    }
  }