Automatic Number Plate Recognition Technology A universal and efficient algorithm for global ANPR application

AUTOMATIC NUMBER PLATE RECOGNITION TECHNOLOGY

1. BACKGROUND With the vehicle applications gaining popularity in daily life, intelligent vehicle management becomes important in many industries. Hikvision ANPR (Automatic Number Plate Recognition) technology can detect and identify the vehicle’s unique license plate number and is an important component of a sophisticated vehicle management system. While Hikvision’s ANPR technology has been approved by many Chinese customers for its high accuracy, lack of a universal license plate format in the overseas market presented a great challenge. Hikvision’s ANPR technology was created to be applied...

2.1. PLATE LOCATING Plate locating technology does not rely on the plate color or character structure, and can locate monolayer (single section) and bilayer (dual section) plates. The plate locating procedure consists of rough locating, false plate filtering, fine locating, and post processing. 2.1.1. ROUGH LOCATING The rough locating procedure works based on the characteristic that the contrast between plate characters and the plate background is very pronounced. It searches the part that matches with the feature in the image to locate the license plate. Figure 2 Rough Locating Result 2.1.2....

Figure 5 Bilayer License Plate 2.2. CHARACTER PARTITIONING Since the plate locating has now obtained the upper and lower borders of the plate characters, the remaining problem is determining the left and right borders of each character. Here are the common character partition (character’s circumscribed rectangle) methods and their advantages and disadvantages.  Vertical Projection This technique finds the wave troughs by observing the projections. Wave troughs are the spaces between the characters, which are used to locate and partition off every character. However, this method cannot judge...

2.2.2. FINE PARTITION Since there are possible problems left by the rough partition such as one character separated into two or more, two characters combined into one, diverse character widths, and inter-embedded characters, Hikvision develops a fine partition algorithm with the most advanced technology, which is a core part of the ANPR technology. 1) To finely separate complicated characters problems such as one character separated into two, or two characters combined into one, the algorithm separates characters based on different preprocessed pictures (such as greyscale picture, outline drawing,...

measure” is adopted: after locating the two layers of the plate, it will always start the partition from the lower layer. This measure can speed up the processing efficiency for bilayer plate. 2.3. CHARACTER RECOGNITION Hikvision’s character recognition algorithm is based on a machine learning neural network algorithm. Compared to the traditional recognition algorithm, it has advantages that it has a character authenticity identification module and supports various kinds of characters recognition, including Arabic numerals, English characters, Chinese characters, Korean characters, Thai characters,...

3. APPLICATIONS Hikvision ANPR technology features the most advanced machine learning algorithm and the image processing measure, and reaches extremely high accuracy. It has the following advantages:  Small resource occupation;  High recognition efficiency;  Great capability: round-the-clock recognition and minimally affected by weather;  Global application: supports Arabic numeric, English characters, and any other language characters. Vietnam ANPR Application Philippine ANPR Application Indian ANPR Application Macau ANPR Figure 10 Hikvision ANPR Global Application Examples Most of the traditional...

AUTOMATIC NUMBER PLATE RECOGNITION TECHNOLOGY