Epameinondas Antonakos bio photo

Epameinondas Antonakos

Manager of Computer Vision at Robotics AI, Amazon in Berlin.

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The Menpo Project
The Menpo Project
Visit menpo.org Visit github.com/menpo

The Menpo Project is a set of BSD licensed Python frameworks and associated tooling that provide end-to-end solutions for 2D and 3D deformable modeling. The project includes training and fitting code for various state-of-the-art methods such as:

  • Active Appearance Model (AAM)
  • Supervised Descent Method (SDM)
  • Ensemble of Regression Trees (ERT) (powered by dlib)
  • Constrained Local Model (CLM)
  • Active Shape Model (ASM)
  • Active Pictorial Structures (APS)
  • Lucas-Kanade (LK) and Active Template Model (ATM)

The Menpo Project also provides:

  • a web-based tool for annotation of bulk data for model training
  • a command line tool for landmark localisation with state-of-the-art pre-trained models
  • generic object detection in terms of a bounding box
  • an elegant standard library with simple dependencies, useful for many areas of computer vision
  • sophisticated visualization with interactive IPython/Jupyter widgets

All of the code is Open Source and can be found over on the Menpo Github Organisation.


The Menpo Project consists of a family of packages (primarily Python), each designed to solve one problem well:


menpo The heart of the Menpo Project. menpo contains all core functionality needed for the project in well tested, mature, stable package. menpo is the numpy of the Menpo ecosystem - the foundation upon which all else is built. Even if you aren't interested in deformable modelling, menpo's minimal dependencies and general algorthims and data structures makes it an ideal standalone library for use in a wide variety of Computer Vision situations.


menpofit Implementations of state-of-the-art 2D deformable models. Each implementation includes training and fitting code. menpofit contains the crown jewels of the Menpo Project - most people are interested in using the Menpo Project for the menpofit package.


menpodetect Wraps a number of existing projects that provide functionalities for training and fitting generic object detection techniques. It is designed in order to have full compatibility with menpofit. Not all of the wrapped projects fall under the same BSD license and so care must be taken when using this project to adhere to the sub-project licenses.


menpo3d A specialized library for working with 3D data. It is largely separate from the core menpo library as it has dependencies on a number of large, 3D specific projects (like VTK, mayavi, assimp) which many people using the Menpo Project would have no use for. You'll want to install menpo3d if you need to import and export 3D mesh data or perform advanced mesh processing.


menpowidgets A key goal of the Menpo Project is to accelerate research in 2D and 3D computer vision by providing powerful visualization tools. menpowidgets contains a collection of Jupyter Notebook Widgets for sophisticated visualization and interactive inspection of the state of all Menpo objects.


menpocli Command Line Interface (CLI) for the Menpo Project that allows to readily use pre-trained state-of-the-art menpofit facial models. This is useful for people that only care to quickly acquire facial landmarks on their images.


landmarker.io An interactive web-based tool for manual annotation of 2D images and 3D meshes. Useful to quickly landmark a single image, or organize a large annotation effort for thousands of files. Features like Snap Mode and Dropbox compatibility make it unique.

Why ‘Menpo’?

Menpo were facial armours which covered all or part of the face and provided a way to secure the top-heavy kabuto (helmet). The Shinobi-no-o (chin cord) of the kabuto would be tied under the chin of the menpo. There were small hooks called ori-kugi or posts called odome located on various places to help secure the kabuto’s chin cord.

Wikipedia, Menpo

Code Example

Let’s build a facial patch-based Active Appearance Model and fit it on a test image, in order to demonstrate the simplicity of using menpo.

First, let’s load the trainset of LFPW (you can download it from here) as:

import menpo.io as mio
from menpo.visualize import print_progress

path_to_images = '/path/to/lfpw/trainset/'

training_images = []
for img in print_progress(mio.import_images(path_to_images, verbose=True)):
    # convert to greyscale
    if img.n_channels == 3:
        img = img.as_greyscale()
    # crop to landmarks bounding box with an extra 20% padding
    img = img.crop_to_landmarks_proportion(0.2)
    # rescale image if its diagonal is bigger than 400 pixels
    d = img.diagonal()
    if d > 400:
        img = img.rescale(400.0 / d)
    # append to list

We can visualize the images using an interactive widget as:

%matplotlib inline
from menpowidgets import visualize_images

Let’s now train a PatchAAM using Dense SIFT features:

from menpofit.aam import PatchAAM
from menpo.feature import fast_dsift

patch_aam = PatchAAM(training_images, group='PTS', patch_shape=[(15, 15), (23, 23)],
                     diagonal=150, scales=(0.5, 1.0), holistic_features=fast_dsift,
                     max_shape_components=20, max_appearance_components=200,

and visualize it:


Let’s now create a Lucas-Kanade Fitter for the patch-based AAM using the Wiberg Inverse-Compositional algorithm, as

from menpofit.aam import LucasKanadeAAMFitter, WibergInverseCompositional

fitter = LucasKanadeAAMFitter(patch_aam, lk_algorithm_cls=WibergInverseCompositional,
                              n_shape=[5, 20], n_appearance=[30, 150])

You can retrieve information about any trained model by:


Let’s load a test image from LFPW testset and convert it to grayscale

from pathlib import Path
import menpo.io as mio

path_to_lfpw = Path('/path/to/lfpw/testset/')

image = mio.import_image(path_to_lfpw / 'image_0018.png')
image = image.as_greyscale()

Let’s also load a pre-trained face detector from menpodetect and try to find the face’s bounding box in order to initialize the AAM fitting

from menpodetect import load_dlib_frontal_face_detector

# Load detector
detect = load_dlib_frontal_face_detector()

# Detect
bboxes = detect(image)
print("{} detected faces.".format(len(bboxes)))

# View
if len(bboxes) > 0:
    image.view_landmarks(group='dlib_0', line_colour='red',
                         render_markers=False, line_width=4);
Visualize bounding box initialization

The fitting can be executed as

# initial bbox
initial_bbox = bboxes[0]

# fit image
result = fitter.fit_from_bb(image, initial_bbox, max_iters=[15, 5],

# print result

which prints

Fitting result of 68 landmark points.
Initial error: 0.1689
Final error: 0.0213

The fitting result can be visualized as

Visualize fitting result

and the fitting iterations as

Visualize fitting iterations

Also, fitting result widget can be called as