FPGA Logic Design And Implementation Of Multispectral Flatbed Scanner

Flatbed scanner is a common image acquisition equipment,which can collect white light color images.However,in the office occasions involving anti-counterfeiting tickets,infrared and ultraviolet images need to be collected for identification,which requires the scanner to have multi spectral image acquisition function.CIS(Contact Image Sensor)has the advantages of compact structure,light weight and no geometric distortion,so it is suitable for multispectral flatbed scanner.In this thesis,FPGA(Field Programmable Gate Array)is used to design and implement the control logic of multispectral flatbed scanner based on CIS,which mainly solves the logic design problems of image data acquisition,processing,caching and transmission.Firstly,according to the function and performance requirements of the multispectral flatbed scanner,the selection of key components is completed,and the functional requirements of the control logic are analyzed.The overall scheme of FPGA logic is formulated,the functional modules are divided,the bus relations between modules are defined,and the FPGA clock domain is planned.Secondly,aiming the problem that the hardware implementation of the existing bicubic interpolation consumes a lot of resources,an improved bicubic interpolation algorithm is proposed in this thesis,and its calculation method is simplified.Compared with the hardware interpolation implementations in the literature,the hardware implementation of the improved algorithm has the same image quality,45% lower multiplier resource consumption and 13% higher maximum operating frequency.Thirdly,according to the requirements of the overall scheme for each module,the logic design and optimization of FPGA are completed.In order to reduce the resource consumption of image data reorganization splicing logic,a FIFO+DDR2 reorganization splicing structure is designed.In order to improve the read and write efficiency of DDR2 SDRAM,the allocation of DDR2 storage space is optimized,and the read and write control logic is designed to realize the cache.In order to achieve the image amplification function of the scanner,the image processing module is designed,and the ping-pong cache structure is used in the module to improve the calculation speed of image interpolation enlargement.According to the overall scheme and the resource requirements of the function modules,the selection of FPGA chip is completed,and the above achievements are integrated into the chip.The product design of the multispectral flatbed scanner based on the FPGA chip has been completed.According to the test result,this product runs stably,and is capable of collecting white light color images,infrared images and ultraviolet fluorescence images with good image quality and high scanning speed.In the meanwhile,the product is integrated with the function of image hardware interpolation enlargement,and meets the expected requirements of both function and performance.