This invention discloses an adaptive FPGA
license plate
recognition system and anti-interference method for
severe weather, belonging to the field of embedded
digital image processing technology. To address the technical shortcomings of traditional FPGA
license plate recognition systems, such as fixed
image processing parameters, low recognition accuracy in
severe weather, and reliance on external weather sensors, this invention sets up a weather feature discrimination module and an adaptive anti-interference preprocessing module. The weather feature discrimination module constructs an 8×8 pixel hardware sliding sampling window based on a
shift register, extracting four types of features in parallel using pure hardware: average image brightness, gray-level squared cumulative dispersion,
noise quantity, and highlight pixel ratio. It also distinguishes character edges from
noise by combining
gradient direction, and outputs a 3-bit binary weather code through a four-channel hardware
comparator, achieving automatic judgment of sensorless weather conditions. The adaptive anti-interference preprocessing module integrates four mutually exclusive
hardware circuits: a
fog enhancement circuit, a rain filtering circuit, a strong light suppression circuit, and a nighttime
noise reduction and brightness enhancement circuit. It adaptively switches the corresponding anti-interference
processing link according to the weather code and uses
clock gating technology to
shut down idle circuits to reduce dynamic
power consumption. This invention uses addition, subtraction, and shift operations to implement hardware logic, avoiding floating-point operations. It is compatible with low-end and mid-range FPGA chips, with a single-frame
image processing latency of ≤6ms. Under harsh working conditions, the
license plate recognition accuracy can reach over 95%, making it suitable for outdoor traffic checkpoints and embedded capture devices.