Thursday, November 19, 2009

My Neural Network Algorithm

Since 3 days I was trying to write a sample neural network algorithm for boolean value inputs and output. My neural network contains three inputs and one output.I used one hidden layer with two hidden units. The AND operation on the three inputs gives the output. I wrote down a truth table and supplied this as a set of training examples to the algorithm. I initialized the weights to some random numbers(between 0 - 0.05). Then I ran the algorithm. After 50 iterations over the training examples, 6 out of 8 examples are consistent with the output. After that I iterated through the examples many times(nearly 2000000) but still only those 6 same samples are consistent. The input weights almost converge after 2000 trails but the hidden weights(weights on the links between hidden units and output units)never converge. They keep oscillating between 2 samples. I even tried by reducing the 'eta' value. But all 8 samples are never consistent with a set of weights.

Sunday, November 15, 2009

Another good paper

There is another paper that I came across,

A HIERARCHICAL NEURAL NETWORK FOR HUMAN FACE DETECTION - PAUL JUELL and RON MARSH.

The approach used in the paper uses four neural network. Three of them are used to detect eyes, nose and mouth. The output of these networks are fed into the fourth neural network. I feel the concept and results are well explained but the implementation details are not so clear.

Interesting paper

Today I came across many good papers on face detection using neural networks. I read one of them which is very interesting. The URL is

http://www.ri.cmu.edu/pub_files/pub1/rowley_henry_1998_1/rowley_henry_1998_1.pdf

The paper is old but explains all concepts very well. The paper compares its approach with all existing approaches.

Friday, November 6, 2009

Aim of the Project

The basic aim of this project is to create a neural network that takes an image as input and tells us if the input image contains faces or not. We plan to use Backpropagation Algorithm for training. Once we complete this part we plan to extend our project by analysing different neural network algorithms and find which is most efficient.