At first, the license plate recognition algorithm was developed and verified on Matlab with a good recognition rate using a license plate image database.
The license plate image database was then converted into .hex file using a simple Matlab code and the .hex files was loaded into FPGA for testing. Example code (Full code not given) and detailed test environment for the license plate recognition system on Xilinx FPGA Spartan-6 are here.
To test the license plate recognition system, license plate image database is read from the .hex files using $readmemh in Verilog into FPGA. Then, the database is processed through the license plate recognition system. The license numbers are recognized and displayed on single LEDs.
The demonstration video for the license plate recognition system on FPGA:
Other image processing project, you can refer to this. It was kind of a tutorial on how to get started with image processing on FPGA.
Tutorial on how to load image/text file into FPGA using Verilog or VHDL: here.