Description
In this assignment, you will experiment with two different classifiers for gender classification:
SVMs and Bayesian classifier.
Data Set and experiments: The dataset to be used in your experiments contains 400 frontal
images from 400 distinct people, representing different races, with different facial expressions,
and under different lighting conditions. The 400 images have been equally divided between
males and females. Histogram equalization has been applied to each normalized image to
account for different lighting conditions. The data, which is available from the course’s webpage,
contains images of two different sizes: 16×20 and 48×60; you would need to experiment with
each image size separately and compare your results. For each classifier, you need to report
the average error rate using a three-fold cross-validation procedure. For this, we have randomly
divided the dataset three times as follows:
Fold 1: Training (69M, 65F), Validation (73M, 60F), Test (58M, 75F)
Fold 2: Training (62M, 72F), Validation (58M, 75F), Test (80M, 53F)
Fold 3: Training (71M, 63F), Validation (67M, 66F), Test (62M, 71F)
Note that the validation set is typically used for parameter optimization. Since you will not need
to optimize any parameters in this assignment, use both the validation set and test set for
testing purposes by simply combining them into one set. Using each fold, compute the test error
and then average all three errors to report the average error.
For each image, we have pre-computed its eigen-face representation; you should be
training/testing each classifier using the first 30 eigen-features only (i.e., the ones corresponding
to the top 30 eigenvectors). The file naming convention for each file is as follows: trPCA_xx for
training, valPCA_xx for validation, and tsPCA_xx for testing; see “descr” file for more
information. Note that the eigenvalues and eigenvectors have been provided in the files EVs_xx
and PCs_xx for completeness, however, you will not need them in your experiments.
Experiment 1: Apply Support Vector Machines (SVMs) for gender classification. You will be
using the LibSVM implementation. Experiment both with polynomial and RBF kernels as well as
different C values. For consistency, try d=1, 2, and 3 for the polynomial kernel (note that
LibSVM provides two extra parameters for the polynomial kernel; to be consistent with the
lecture, set γ=1 and c0=0). In the case of the RBF kernel, try σ=1, 10, and 100. For the C value,
try C=1, 10, 100, and 1,000. Report your best results both for the 16×20 and 48×60
datasets. Warning: make sure that the data is provided in the format required by LibSVM;
otherwise, it will not work correctly.
Experiment 2: For comparison purposes, apply the Bayes classifier for the same problem.
Model the male and female classes using a Gaussian distribution and use ML estimation to
estimate the parameters for each class. Use equal prior probabilities (e.g., P(ω1)= P(ω2)).
Compare your results with those obtained using SVMs.
PROJECT REPORT SUBMISSION REQUIREMENTS
1. Cover Page. The cover page should contain Project title, Project number, Course
number, Student’s name, Date due, and Date handed in.
2. Technical discussion. This section should include the techniques used and the principal
equations (if any) implemented.
3. Discussion of results. A discussion of results should include major findings in terms of
the project objectives, and make clear reference to any figures generated.
4. Division of work: Include a statement that describes how the work was divided between
the two group members.
5. Program listings. Includes listings of all programs written by the student. Standard
routines and other material obtained from other sources should be acknowledged by
name, but their listings should not be included.
A hard copy is required for items 1-4, submitted to the instructor in the beginning of the class on
the due date. Item 5 should be emailed to the instructor, as a zip file, before class on the due
date.
