IJE TRANSACTIONS B: Applications Vol. 26, No. 11 (November 2013) 1347-1356   

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M. Ashourian, N. Daneshmandpour, O. Sharifi Tehrani and P. Moallem
( Received: October 20, 2012 – Accepted in Final Form: May 16, 2013 )

Abstract    License plate recognition (LPR) by using morphology has the advantage of resistance to brightness changes; high speed processing, and low complexity. However these approaches are sensitive to the distance of the plate from the camera and imaging angle. Various assumptions reported in other works might be unrealistic and cause major problems in practical experiences. In this paper we considered morphological approaches and improved them by using adaptive techniques to achieve more compatibility with practical applications. We examined the developed system on several car plate image databases with different conditions like different camera distance, and different car views. The average achieved rate of success was 89.95% for car plate location recognition, which is around 6.0% higher than previous related report of morphological methods. We further implemented the system on an FPGA platform.


Keywords    License Plate Recognition, Car Plate Location Recognition, Real Time Implementation, Adapted Morphology


چکیده    سیستمهای تشخیص پلاک مبتنی بر مورفولوژی دارای امتیازاتی همچون حساسیت کمتر به تغییرات روشنایی ؛ سرعت بالاتر و پیچیدگی پایین می باشند. با این حال این روشها به فاصله از دوربین و زاویه عکس برداری حساسند. فرضیات ساده کننده ای که در بسیاری از مقالات مبتنی بر روش مورفولوژی مطرح شده اند در یک پیاده سازی عملی واقعی نبوده و باعث کاهش کارایی می گردند. در این مقاله روش مورفولوژی انتخاب گردیده است و روشهای وفقی جهت بهبود کارایی آن در عمل اعمال گردیده اند. روش طراحی شده بر روی چند پایگاه تصویری شامل تصاویری متنوع از نظر فاصله و زاویه عکس برداری مورد آزمایش قرار گرفت. نتایج به طور متوسط 89.95 درصد تشخیص درست منطقه پلاک را نشان می دهد که حدود 6 درصد بیشتر ازدیگر روشهای تشخیص پلاک مبتنی بر مورفولوژی است . علاوه بر ایت امکان پیاده سازی سیستم به صورت سخت افزاری نیز ارزیابی گردید.


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