Saturday, November 19, 2016

Setting up Keras and Anaconda Python on Ubuntu 16.10

I’ve been using Anaconda Python for most of my Machine Learning experiments, mainly because of the flexibility it gives with the isolated Python environments. I recently did a post on how to install Keras on Anaconda on Windows.

I’m planning to switch to Linux for few of my experiments, so I decided to try out setting up Anaconda Python and Keras from scratch on Ubuntu. I’ll be using the latest Ubuntu 16.10 (Yakkety Yak) 64-Bit for this.

Note: The screenshots I captured are from a virtual machine with Lubuntu 16.10 (the LXDE flavor of Ubuntu). But the steps and commands are exactly the same for the standard Ubuntu desktop as well.

First and foremost, get and install the latest updates in Ubuntu, (Reboot the machine if necessary after updating.)
 sudo apt-get update  
 sudo apt-get upgrade  

Then, we’ll install the following necessary packages,
 sudo apt-get install build-essential cmake git unzip pkg-config  
 sudo apt-get install libopenblas-dev liblapack-dev  

Now, on to installing Anaconda. Head over to the Anaconda Python Downloads page, and get the Linux installer for Anaconda. We’ll be getting the Python 3.5 64-Bit package.
Go to the Anaconda Download page and download the Anaconda Python 3.5 64-Bit package for Linux
Download the Anaconda Python 3.5 64-Bit package for Linux

This will download a file named Anaconda3-4.2.0-Linux-x86_64.sh (the version numbers might be different based on the latest version available at the time of the download).

Saturday, November 12, 2016

Getting the LeNet model working with Face Recognition

In my last post, I talked about how the LeNet Convolutional Neural Network model is capable of handling much more complex data than the intended MNIST dataset. We saw how it got ~99% accuracy when it learned to identify 10 faces from the raw pixel intensities.

So, let’s see the code I used to get it working.

First of all, I needed a training dataset. For that, I created a set of face images of 10 subjects with around 500 images each.

Few of the images from the training dataset
The training dataset (yep, that's my face)

I use a file naming convention as <subject_label>-<subject_name>-<unique_number>.jpg (e.g. 0-Thimira-1475137898.65.jpg) for the training images to make it easier to read in and get the metadata of the images in one go. (I will do a separate post on how to easily create training datasets of face images like this).

We'll mainly be using Keras to build the model, and scikit-learn for some utility functions. We’ll need to import the following packages,
 from sklearn.cross_validation import train_test_split  
 from keras.optimizers import SGD  
 from keras.utils import np_utils  
 import numpy as np  
 import argparse  
 import cv2  
 import os  
 import sys  
 from PIL import Image  

Monday, November 7, 2016

Can the LeNet model handle Face Recognition?

I recently followed a blog post - at PyImageSearch by Adrian Rosebrock - on using the LeNet Convolutional Neural Network model on the MNIST dataset - i.e. use for handwritten digit recognition - using Keras with Theano backend. I was able to easily try it out thanks to the very detailed and well thought out guide.

The LeNet model itself is quite simple, just 5 layers. Yet it performs impressively well on the MNIST dataset. We can get around 98% accuracy with just 20 iterations of training with ease.

The training time for the model is also quite low. I tested on my MSI GE60 2PF Apache Pro laptop with CUDA enabled, and the training time was just 2 minutes 20 seconds on average. On CPU only (with CUDA disabled) it took around 30 minutes.

LeNet giving 98% accuracy on MNIST data
LeNet giving 98% accuracy on MNIST data
As you can see, we got 98.11% accuracy, and it has correctly classified a digit that has been cut-off.

It even classifies a quite deformed '2' correctly.
LeNet correctly classifying a deformed digit
LeNet correctly classifying a deformed digit

Saturday, November 5, 2016

What is the image_dim_ordering parameter in Keras, and why is it important

Update 9/May/2017: With Keras v2, the image_dim_ordering parameter has been renamed to image_data_format. Check my updated post on how to configure it.

If you remember my earlier post about switching Keras between TensorFlow and Theano backends, you would have seen that we switched the image_dim_ordering parameter also when switching the backend. For TensorFlow, image_dim_ordering should be "tf", while for Theano, it should be "th".

So, what is this parameter, and where does it affect?

It has to do with how each of the backends treat the data dimensions when working with multi-dimensional convolution layers (such as Convolution2D, Convolution3D, UpSampling2D, Copping2D, … and any other 2D or 3D layer). Specifically, it defines where the 'channels' dimension is in the input data.

Both TensorFlow and Theano expects a 4 dimensional tensor as input. But where TensorFlow expects the 'channels' dimension as the last dimension (index 3, where the first is index 0) of the tensor – i.e. tensor with shape (samples, rows, cols, channels) – Theano will expect 'channels' at the second dimension (index 1) – i.e. tensor with shape (samples, channels, rows, cols). The outputs of the convolutional layers will also follow this pattern.

So, the image_dim_ordering parameter, once set in ~/.keras/keras.json, will tell Keras which dimension ordering to use in its convolutional layers. 

However, if you like to override the dimension ordering programmatically, you do it by using the dim_ordering parameter when initializing a convolutional layer:
 model = Sequential()  
   
 model.add(Convolution2D(64, 3, 3, border_mode='same', input_shape=(3, 256, 256), dim_ordering='th'))  

The dim_ordering parameter is available in all the multi-dimensional convolution layers.

Related posts:
image_data_format vs. image_dim_ordering in Keras v2

Related links:
https://keras.io/layers/convolutional/#convolution2d


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Thursday, November 3, 2016

Difference between Artificial Intelligence, Machine Learning, and Deep Learning

Update: Check out the new and updated article on What is Deep Learning, and how it relates to Artificial Intelligence and Machine Learning.

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You may have heard the terms Artificial Intelligence, Machine Learning, Deep Learning and you maybe trying to figure out what they mean, and whether these terms can be used interchangeably.

I've also had the same questions when I started diving in to the field. And a recent post in the Nvidia Blog brought back the question.

So here’s a simplified explanation on how each of those terms came to be, and how they relate to each other.


Artificial Intelligence

 

Artificial Intelligence is the idea that machines (or computers) can be built that has intelligence parallel (or greater) to that of a human, giving them capability to perform tasks that requires human intelligence to perform.

The idea of an intelligent machine has been around since 1300 BC, and through 19th century. But the Dartmouth Conferences in 1956 is what’s commonly considered as the starting point of the formal research field of Artificial Intelligence. Since then the field of AI has gone through many ups-and-downs and has branched out into many sub fields. There has been attempts at applying AI for various fields – such as medical, finance, aviation, machinery etc. – with various degrees of success.

Around the late 1990s and early 2000s, the researchers identified a problem in their approach to AI, which was slowing down the success of AI – in order for us to artificially crate a machine with an intelligence, we would first need to understand how intelligence work. But even today, we do not have a complete definition of what we call "intelligence".

In order to tackle the problem, they decided to go ground-up – rather than trying to build an intelligence, we could look in to building a system that can grow its own intelligence. This idea created the new sub-field of AI called Machine Learning.

Tuesday, November 1, 2016

Switching between TensorFlow and Theano on Keras

Keras speeds up the task of building Neural Networks by providing high-level simplified functions to create and manipulate neural models. It itself does not provide the lower level neural and deep learning functions, but it’s rather meant to be run on an engine – which Keras refers to as a “backend” - which would provide such low-level functions.

Currently, Keras supports two such backends – TensorFlow and Theano.

The current version of Keras (v1.1.0 at the time of this writing) uses TensorFlow by default.

Most models written on top of Keras can be switched to a different backend without changes – at least it’s what’s said in the documentation. I’m yet to test this.

Which backend Kesas will use is defined in the Keras config file, which is located in the .keras directory in your home directory:
e.g.: on linux it would be ~/.keras/keras.json and on windows you can get to it on %USERPROFILE%\.keras\keras.json

For the default of using the TensorFlow backend, use the following config,
 {  
   "image_dim_ordering": "tf",  
   "epsilon": 1e-07,  
   "floatx": "float32",  
   "backend": "tensorflow"  
 }  

Notice the "backend" is set to "tensorflow" and "image_dim_ordering" is set to "tf".

To use the Theano backend, use the following,
 {  
   "image_dim_ordering": "th",   
   "epsilon": 1e-07,   
   "floatx": "float32",   
   "backend": "theano"  
 }  

Apart from the obvious "backend": "theano", note that "image_dim_ordering" is set to "th".

See my new post to see what the image_dim_ordering parameter in Keras does, and why is it important to set it properly.

Update: If you use Jupyter notebooks, and need to switch between TensorFlow and Theano backends quite often, fellow blogger desertnaut has a solution to dynamically switch the backend. Check out his solution at: Dynamically switch Keras backend in Jupyter notebooks

Related posts:
What is the image_dim_ordering parameter in Keras, and why is it important

Related links:
https://keras.io/backend/

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