IJSRSET1623213 | Received: 20 June 2016 | Accepted : 24 June 2016 | May-June 2016 [(2)3: 793-800]
© 2015 IJSRSET | Volume 1 | Issue 6 | Print ISSN : 2395-1990 | Online ISSN : 2394-4099
Themed Section: Engineering and Technology
793
Real Time License Plate Recognition via Watershed and Viterbi
Algorithm
Kaushalya Bakde , Suyash Agrawal
Computer Science & Engineering Department, Rungta College of Engineering & Technology, Kurud Kohka Bhilai, Chhattisgarh, India
ABSTRACT
License Plate Recognition (LPR) is the extraction of vehicle license plate information from still images or frame
sequences (videos). Character segmentation & recognition has long been a critical area of the OCR process. The
characters are detected in the order defined by the matching quality. In this paper three main procedures watershed,
thresholding and hidden markov model based Viterbi algorithm was used to perform license plate segmentation and
recognition tasks. The watershed transformation with thresholding algorithm based on the gradient approach gives
good results for segmentation of characters. This is mainly designed for Indian Car license plate. The procedure
follows a simple and effective way to segment and recognize the characters. This paper also presents extensive
experiments using real video sequences to verify the proposed method.
Keywords: License plate recognition (LPR), Watershed algorithm, Thresholding, Hidden markov Viterbi algorithm,
Optical Character Recognition (OCR) for cars.
I. INTRODUCTION
Segmentation and recognition are two important tasks in
image processing and computer vision. License Plate
Recognition (LPR) is an integral part of Intelligent
Transportation Systems (ITS). License plates are used
for identification of vehicles all over the nations so it is
illegal for two vehicles to have the same license number.
License plate recognition (LPR) algorithms in images or
videos are generally composed of the following three
modules: (1) license plate detection, (2) character
segmentation, and (3) recognition. The first two steps
incorporate image processing techniques on still images
or frame sequences (videos), whose evaluation relies on
the true recognition rate and the error recognition rate.
Among these steps, a very critical step is the license
plate segmentation, which directly affects the overall
system performance. A broad range of methods for
license plate segmentation have been reported in the
literature.
Vehicle registration plates are formatted as follows:
Plates for private car and motorized two-wheeler
owners have black lettering on a white background
(e.g., CG.18.K.1316).
Commercial vehicles such as taxis and trucks have
a yellow background and black text
(e.g., MH.12.CD.2544).
Commercial vehicles available on rent for self-drive
have yellow lettering on a black background
(e.g., KA.03.AB.8192).
The President of India and state governors travel in
official cars without license plates. Instead they have
the Emblem of India in gold embossed on a red plate.
Some Indian number plates are shown below:
Figure 1. Samples of license plates in India