Title :
Local enhancement of car image for license plate detection
Author :
Abolghasemi, Vahid ; Ahmadyfard, Alireza
Author_Institution :
Shahrood Univ. of Technol., Shahrood, Iran
Abstract :
In this paper we address the problem of car plate detection. In the first part of algorithm we propose a method for enhancing car plate regions. We estimate the local density of vertical edges in the image as a criterion for local enhancement. In the second part, the vertical edges from the enhanced image is then extracted and feed to a morphological filter to constitute candidate regions for the place of car plate. This filter aims to connect vertical edges closer than the size of a defined structuring element. The output of this process is a number of connected components among which the plate region is. We use some geometrical features of car plate such as shape and aspect ratio to filter out non-plate regions from the candidate list. Using the correlation between the candidate regions and the model of car plate, the most probable region is found. The result of enhancement on car images shows the ability of the proposed method for improving the contrast of plate region(s) in the image. The experimental results on out-door car images confirms the robustness of the proposed method against the severe imaging condition.
Keywords :
edge detection; filtering theory; image enhancement; car image local enhancement; car plate detection; car plate region enhancement; license plate detection; morphological filter; out-door car images; plate region contrast; severe imaging condition; vertical edge extraction; vertical edge local density estimation; Feature extraction; Image edge detection; Licenses; Morphology; Shape; Signal processing; Signal processing algorithms;
Conference_Titel :
Signal Processing Conference, 2007 15th European
Conference_Location :
Poznan
Print_ISBN :
978-839-2134-04-6