Update README.md

Author: pavancm

Diff for: README.md

@@ -1,6 +1,14 @@
 # Visual-Information-Fidelity (VIF) - Python
 
 This repository contains python implementation of steerale pyramid version of Visual Information Fidelity (VIF) proposed in [1]
-This is a replication of MATLAB version released by the authors of [1] which is available [HERE](http://live.ece.utexas.edu/research/Quality/ifcvec_release.zip)
+This is a replication of MATLAB version released by the authors of [1] which is available [HERE](http://live.ece.utexas.edu/research/Quality/ifcvec_release.zip).
 
 ## Dependencies
+1) Python (>=3.5)
+2) Steerable Pyramid Toolbox (PyPyrTools) [link](https://github.com/LabForComputationalVision/pyPyrTools)
+
+## Usage
+Let imref and imdist denote reference and distorted images respectively. Then the VIF value is calculated as
+VIF = vifvec(imref, imdist)
+
+A demo code is provided in test.py for testing purposes