sign2text

Real-time AI-powered translation of American sign language to text

The project focuses on translating American Sign Language (ASL) fingerspelled alphabet (26 letters). I utilised transfer learning to extract features, followed by a custom classification block to classify letters. This model is then implemented in a real-time system with OpenCV - reading frames from a web camera and classifying them frame-by-frame. This repository contains the code & weights for classifying the American Sign Language (ASL) alphabet in real-time.

This project was developed as my portfolio project at the Data Science Retreat (Batch 09) in Berlin. Please feel free to fork/comment/collaborate! Presentation slides are available in the repo :)

Dataset - https://drive.google.com/drive/folders/1-t8rgN3eOW99KGDy7U0HJhrbbwOe-5Wh?usp=sharing

All the data is already split into train/validation subsets, and labelled with letters from A-Z.

NOTE - the Massey dataset I've included is already pre-processed and is only a subset of the entire dataset (part 5). I added padding due to odd shaped images, and also dropped a colour channel as there was a lot of green screen background in the images. Dropping the colour channel didn't cause any significant changes in performance so I've left it in. You can get the raw data directly from Massey University.

Usage

The entire pipeline (web camera -> image crop -> pre-processing -> classification) can be executed by running the live_demo.py script.

The live_demo.py script loads a pre-trained model (VGG16/ResNet50/MobileNet) with a custom classification block, and classifies the ASL alphabet frame-by-frame in real-time. The script will automatically access your web camera and open up a window with the live camera feed. A rectangular region of interest (ROI) is shown on the camera feed. This ROI is cropped and passed to the classifier, which returns the top 3 predictions. The largest letter shown is the top prediction, and the bottom 2 letters are the second (left) and third (right) most probable predictions. The architecture of the classification block will be described further in Sections 4/5.

Dependencies

The code was developed with python 3.5 and has been tested with the following libraries/versions:

• OpenCV 3.1.0
• Keras 2.0.8
• tensorflow 1.11 (cpu version), it will also run with the gpu-version
• numpy 1.15.2
• joblib 0.10.3

NOTE - feature extraction using the pre-trained models in Keras was run on an AWS EC2 p2.8xlarge instance with the Bitfusion Ubuntu 14 TensorFlow-2017 AMI. Packages had to be manually updated, and Python 2 is the standard version. You can either update to Python 3, or edit the scripts to work with Python 2 (the only issues should be the print statements)

Running the Live Demo

When running the script, you must choose the pre-trained model you wish to use. You may optionally load your own weights for the classification block.

$ python live_demo.py --help
usage: live_demo.py [-h] [-w WEIGHTS] -m MODEL

optional arguments:
  -h, --help            show this help message and exit
  -w WEIGHTS, --weights WEIGHTS
                        path to the model weights

required arguments:
  -m MODEL, --model MODEL
                        name of pre-trained network to use

NOTE - On a MacBook Pro (macOS SIERRA 16GB 1600MHz DDR3/2.2 GHz Intel Core i7) using the CPU only, it can take up to ~250ms to classify a single frame. This results in lag during real-time classification as the effective frame rate is anywhere from 1-10 frames per second, depending on which model is running. MobileNet is the most efficient model. Performance for all models is is significantly improved if running on a GPU.

1. American Sign Language

There are no accurate measurements of how many people use American Sign Lanuage (ASL) - estimates vary from 500,000 to 15 million people. However, 28 million Americans (~10% of the population) have some degree of hearing loss, and 2 million of these 28 million are classified as deaf. For many of these people, their first lanugage is ASL.

The ASL alphabet is 'fingerspelled' - this means all of the alphabet (26 letters, from A-Z) can be spelled using one hand. There are 3 main use cases of fingerspelling in any sign language:

(i) Spelling your name (ii) Emphasising a point (i.e. literally spelling out a word) (iii) When saying a word not present in the ASL dictionary (the current Oxford English dictionary has ~170,000 words while estimates for ASL range from 10,000-50,000 words)

This project is a (very small!) first step towards bridging the gap between 'signers' and 'non-signers'.

2. Pre-processing

coming soon I promise

3. Transfer learning & feature extraction

coming soon

4. Training

coming soon

5. Real-time system

coming soon

6. References

https://research.gallaudet.edu/Publications/ASL_Users.pdf https://blog.keras.io/building-powerful-image-classification-models-using-very-little-data.html