PICO Face Detector

A small JavaScript library for detecting faces using the PICO algorithm with the face rotation invariant implementation.

Usage

An example of using the basic functions of the library:

// load cascade
fetch('./data/classifier.dat')
  .then(function(response) {
    if (!response.ok) throw Error(response.statusText || 'Request error');
    return response.arrayBuffer();
  })
  .then(function(cascade) {
    // create face detector with options
    return PicoFace(cascade, {
      shiftfactor: 0.1, // move the detection window by 10% of its size
      scalefactor: 1.1, // resize the detection window by 10% when moving to the higher scale
      initialsize: 0.1, // minimum size of a face (10% of image area)
      rotation: [0, 30, 330], // rotation angles in degrees
      threshold: 0.2, // overlap threshold
      memory: 3 // number of images in the memory
    });
  })
  .then(function(detect) {
    // image = ImageData
    return detect(image);
  })
  .then(function(dets) {
    // dets = [{ r: rows, c: cols, s: size, q: quality, a: angle }]
    console.log(dets);
  });

All parameters of the library are set in the constructor, here is their description:

| Parameter | Default | Description | |-------------|--------------|---------------------------------------------------------------------------------------| | shiftfactor | 0.1 | Sliding window movement step as a percentage (10%) of the image size | | scalefactor | 1.1 | Sliding window resizing step as a percentage (10%) of image size | | initialsize | 0.1 | Initial size of the sliding window as a percentage (10%) of the image size | | threshold | 0.2 | Percentage (20%) of intersections of found candidates for grouping them into one area | | rotation | [0] | Array of rotation angles to be searched (0 to 360 in 1 degree increments) | | memory | 1 | Number of images (frames) in memory to improve detection quality |

The output is an array of areas where the algorithm assumes there are faces. Here is a description of this area:

| Feature | Description | |-------------|--------------------------------------------------------------------------------------| | c | X-coordinate of the center of the found face area | | r | Y-coordinate of the center of the found face area | | s | Size of found area (width and height or diameter) | | q | Detection quality (higher is better quality) | | a | Rotation angle of the image (the most likely one listed in the rotation parameter) |

Build and run

Build the library bundle in the directory ./dist/:

npm install
npm run build

Start the demo webserver:

npm run dev

Related projects

• PICO: https://github.com/nenadmarkus/pico
• picojs: https://github.com/tehnokv/picojs
• tracking.js: https://github.com/eduardolundgren/tracking.js