Zheng Cheng-yong. A novel license plate location method on RGB color space[J]. Journal of Image and Graphics, 2010, 15(11): 1623. DOI: 10.11834/jig.20101107.
License plate(LP) location is key to vehicle license plate auto recognition system. In this paper
we propose a novel LP location method on RGB color space
which includes four steps: color feature extraction
feature images binaryzation
area filling and de-noising with morphology processing
plate candidate regions verification. Traditional color feature extraction is sensitive to iluminition based on which
we propose a new color feature extraction method that doesnt include the intensity component. For plate candidate regions verification
we discards some geometry features such as the area
length/width ratio
rectangle degree etc
those of which are widely used but sensitive to image size
and we utilizese the special characteristic of LP on character number and character arrangement uniformity to verify the candidate regions. 605 images with various size and illumination condition were tested
success rate of LP location was over 96%
which shows the color feature extraction method is robust to illumination change
and the plate verification is suitable for various image size.