Showcase: Deep learning in the cloud. Building a handwritten character recognition model with GNU R and MXNet with Amazon Web Services on GPU instances.

Business story behind the showcase

Optical character recognition (OCR) for handwritten text is applicable in areas where several documents are being used in business for processing large amounts of paper documents. One example could be a traditional post operator that wants to automatically process information on the envelopes. The envelopes are usually not neatly adressed and standard OCR solutions fail in this area. A custom-made character recognition engine designed for this task might receive much better quality level.

Approach

The showcase presents two main things:

• Construction of deep laerning models with MXNet library
• How to run GPU computing in the cloud with Amazon Web Services

Prerequisites

We use bitfusion.io Scientific Computing AMI

The AMI contains Ubuntu 14 along with a R installation along with CUDA drivers. Additionally we have installed MXNet running the following commands:

• sudo apt-get update
• sudo apt-get install -y build-essential git libblas-dev libopencv-dev
• git clone --recursive https://github.com/dmlc/mxnet

Next modify config.mk by setting the following keys:

 USE_CUDA = 1
 USE_CUDA_PATH = /usr/local/cuda
 USE_BLAS = atlas

Finally, compile mxnet with the command make –j4

Usage instruction

1. Install R packages 01_install_packages.R
2. Prepare the dataset 02_download_datasets.R
3. Declare layers for the deep neural network 03_declare_mlp_model.R
4. Create data iterators for seuential data reading 04_prepare_data_iterators.R
5. Fit the model to the data 05_fit_mlp_model.R
6. If the fitting process is interrupted a script for resuming computation state can be used: 06_restart_mlp_model.R
7. Perform predictions and observe the results 07_predict_mlp_model.R

What next

This example presents one possible usage of deep learning models for classification of images. One important problem is selection of an optimal structure for a deep neural network. This requires execution of several experiments for measuring predictive capabilities for various network topologies. Amazon Web Services comes forward to this need and offers very large GPU instances. The flagship offering is a p2.16xlarge offering 16 x GPU Nvidia TESLA K80 with a total of 80'000 GPU cores. This machine availabe from around $2.10 on AWS spot market would make it to the list of Top Supercomputers just 10 years ago.