NEW PRODUCT & TECH
Zhang Ruihao, Li Xiaoqi, Dang Lizhi, Wang Yunfeng, Hong Yingping
Integrated Circuits and Embedded Systems.
2023, 23(12):
55-58.
Due to the limitations of semiconductor technology,the system structure of image sensor column parallel readout circuits is prone to column to column mismatch due to process deviations,resulting in uneven brightness of the output image in the vertical direction,manifested as vertical stripes with varying brightness,which is also known as FPN noise.FPN noise seriously affects image quality.This design is based on the moment matching method and improves it,proposing an FPN noise removal algorithm for image sensors.Firstly,when the system is powered on,let the image sensor collect 300 randomly different frames of images,and then calculate the column pixel mean and cumulative pixel mean of all images.The current column mean minus the cumulative pixel mean is the correction value of the current column of the image sensor.This design uses Zynq series ARM+FPGA heterogeneous SoC as the implementation platform,OV6946 as the image sensor,and Vivado HLS for the development of video stream processing algorithm IP with AXI-Stream input and output interfaces,which is solidified into Zynq's FPGA.After experiments,this algorithm processes 400×400@30 fps outputs from the OV6946 camera on the Zynq7020 platform with a 50 MHz system clock.The video streaming time is about 3.3 ms,ensuring the real-time output of the video stream.The removal effect of FPN noise has been well achieved,and the application of the algorithm is universal.