# A Deep Learning-Based System for Automatic License Plate Recognition Using YOLOv12 and PaddleOCR
## 3 Data Preparation and Technical Resources
### The Format of Romanian License Plates  
In Romania, the system of vehicle identification through license plates is established by the Traffic Code and the related normative acts, being an integral part of the transport and road safety infrastructure. These plates fulfill an essential identification function and also an administrative and legal one, in the context of national and international traffic.  
Starting with the year 2007, with Romania's accession to the European Union, the format of the plates was harmonized with EU standards [15], including the blue band with the national code \"RO\" (Figure 1). Nevertheless, the Romanian system retains notable particularities, both regarding the typology of the plates and their allocation method (Figure 2).  
License plates issued before the introduction of the new regulations are still accepted and valid. These are still found on the roads of Romania, being used by vehicles registered before the legislative changes. Before the modification of the legislation, the license plates had a combination of letters and numbers, without including European identification elements, such as the flag of the European Union (Figure 1; see (d)).  
Although license plates have often been mentioned in the specialized literature, the present approach offers a more detailed and structured presentation of the Romanian system, with emphasis on its particularities. From the bibliographic analysis carried out, no work has emerged that addresses this topic in depth from a similar perspective.  
As is visible in Figure 1, in Romania there currently exist nine types of valid license plates for vehicles. Thus, each region has multiple types of license plates, which may undergo periodic changes regarding design, dimensions, or structure (in the case of Bucharest license plates, the numeric part may consist of two or, at most, three digits (see (d) and (e)); meanwhile, options (b) and (c) fall into a separate category--(b) is used for long-term temporary numbers, and (c) corresponds to version (e) in format but differs in physical dimensions). These changes impose the necessity of constant updating and improvement of the detection algorithm, in order to ensure high accuracy and optimal adaptability to the new plate formats.  
Each vehicle license plate in Romania follows a standardized structure, composed of a county code (consisting of one or two letters), followed by a number of two or three digits and then a sequence of three letters, for example, Figure 2. This combination is unique for each vehicle and allows for its rapid identification. In some cases, the plates may also contain additional information inscribed below the number, such as the name of the car dealership or the location from where the vehicle was purchased, without affecting the validity of the license plate number itself.  
Figure 1: Vehicle registration numbers in Romania [15]: (**a**) Green license plates. (**b**) Long-term temporary numbers. (**c**) License plates after 2007. (**d**) License plates before 2007. (**e**) License plates after 2007 (different form). (**f**) Diplomatic plates CD (Diplomatic Corps). (**g**) Short-term temporary numbers. (**h**) Diplomatic plates TC (Consular Transport). (**i**) MAI plates (Ministry of Internal Affairs).