Browsing by Author "Wang, Shen-Zheng"

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A cascade framework for a real-time statistical plate recognition system
(2007-06-01)
Wang, Shen-Zheng
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Lee, Hsi-Han
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資訊工程學系
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Department of Computer Science
This paper describes a plate recognition system that can process images rapidly at high accuracy rates. This system is designed to meet the requirements of performance, computational speed, and adaptation for vehicle surveillance applications, such as stolen car detection systems. These requirements are satisfied by adopting a cascade framework, utilizing plate characteristics, and developing fast one-pass algorithms. Our system is composed of three main cascading modules for plate detection, character segmentation, and postprocessing. Each module is further decomposed into several cascading procedures, which are composed of successively more complex rejecters. The first module rapidly rejects a majority of nonplate regions by using low computational gradient features and a one-pass scanning algorithm followed by heavy computational statistical rejecters. The second module rejects a majority of noncharacter regions in a similar manner. A peak-valley analysis algorithm is proposed to rapidly detect all promising candidates of character regions. The third module eliminates the plate characters that do not satisfy the plate specifications. In our experiments, the system can recognize plates over 38 frames per second with a resolution of 640 x 480 pixels on a 3-GHz Intel Pentium 4 personal computer.
APPLICATION OF SPATIOTEMPORAL SEARCH-SPACE REDUCTION IN LICENSE PLATE DETECTION
(2008)
Wang, Shen-Zheng
;
Lee, Hsi-Jian
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資訊工程學系
;
Department of Computer Science
In surveillance applications, search space reduction (SSR) is an essential element to efficient algorithms. In this study, spatial and temporal SSRs are integrated for license plate detection in video sequences; the plates could be extracted robustly and extremely fast. Our method started from spatial SSR. by a bi-level one-pass plate extraction (BOPE) algorithm developed to extract plates accurately even in complicated situations. Moreover, we proposed to exclude repeated patterns with the similar appearances in the same location of consecutive frames, which usually include stopped vehicles or regular backgrounds. For efficiency, repeated patterns were detected only on the results of BOPE, named spatiotemporal SSR, based on a block-based mechanism by estimating the tangent distance, which is invariant to the variations in positions, sizes, rotations, or brightness. To reduce the computational load, the repeated patterns and their measured invariant features could be retained for next estimation. In our experiments, the search space could be reduced up to 87.9% by the spatiotemporal SSR; all plate numbers with the heights ranging from 24 to 40 are extracted correctly. The high performance, average 76 frames per second on a 3G Hz PC, suggests that the real-time goal for surveillance applications could be accomplished.
Cascade plate recognition system
(2007-12-20)
Wang, Shen-Zheng
;
Lee, Hsi-Jian
The present invention discloses a cascade plate recognition system, wherein a compact plate region detection module receives an image, detects the plate area candidates of the image, picks out the sequences having continuous identical pixels from the plate area candidates, performs smearing and filtering on the sequences, extracts connected components from the plate area candidates to obtain compact plate regions, verifies the compact plate regions and outputs the verified compact plate regions; a plate character segmentation and recognition module receives the verified compact plate regions, extracts independent-character regions from each verified compact plate regions, verifies the independent-character regions and recognizes the verified independent-character regions to obtain the information of the plate characters. Thereby, the present invention has the advantages of high accuracy, learning capability and fast realtime operation.
LICENSE PLATE RECOGNITION SYSTEM USING SPATIAL-TEMPORAL SEARCH-SPACE REDUCTION AND METHOD THEREOF
(2009-08-20)
Wang, Shen-Zheng
;
Lee, Hsi-Jian
The present invention discloses a license plate recognition system by utilizing spatial-temporal search-space reduction and method thereof. The license plate recognition system can selects a pixel with character edge feature from the inputted image and a plurality of candidate regions from the image; and detect if the candidate region of the inputted image has been appeared in a preceding image. Then the recognition system in the present invention separates the candidate region into a plurality of blocks, calculates the repeated block based on a current image and a preceding image, and determines whether the candidate region is repeated according to the repeated block. Thus, by discarding the repeated regions, the license plate recognition system in the present invention can avoid redundant calculation and improve the efficiency and performance for recognition of real plate character in the image.
Visual tempo analysis for MTV-style home video authoring
(2008)
Wang, Shen-Zheng
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Chen, Yung-Sheng
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Lee, Shih-Hung
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Kuo, C. -C. Jay
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資訊工程學系
Automatic visual tempo analysis and adaptive shot detection are studied for MTV-style home video authoring. Based upon the significant variation caused by object and background independently, spatial and temporal analysis are integrated for region of interest(ROI) detection in video sequences. To further detect homogeneous shots, visual tempos are proposed to describe the variation. Then, an adaptive segmentation method is presented to automatically detect homogeneous shots using visual tempo cues. A baby video is used as an illustrative example, and the experimental results are encouraged.