A real-time ultra-low light color imaging system based on FPGA

Abstract

This article shows a low light color image acquisition system, The core components of the system are the Fairchild’s SCMOS image sensor CIS1910F1111 and XILINX’s Artix-7 XC7A100T-2CSG324I FPGA, the remarkable advantage of the system is that it can obtain better color imaging effect under lower illumination environment, and the image noise is much less than other similar products. Based on the excellent imaging performance of the image detector, a high performance real-time low-light level color imaging system is developed. This imaging system can obtain the characteristic information of the targets under ultra-low illuminance environment, including the details, colors and so on. The hardware of the low light level imaging system mainly contains a color SCMOS image sensor and a FPGA, a driving circuit of a combination of DDR3, the ultra-low noise power conversion circuit and a Camera-Link and a 3G-SDI interface circuits. The SCMOS chip is used for photoelectric conversion of the shot scene and the FPGA is used for the control of the whole imaging system, image acquisition and image processing, etc, The FPGA software system consists of SCMOS initialize configuration and timing control module, automatic exposure control module, real-time color image processing module, imaging tone mapping module, image denoising module and image enhancement module. The automatic exposure control (AEC) module adaptively adjusts the average gray value of the region of interest. The module automatically calculates the exposure time and gain value of the next frame according to the current frame image data value. The real-time color image processing module includes color restoration, automatic white balance and color spaces conversion, etc. The image denoising module uses the advanced real-time guide-filter algorithm. The image tone mapping module and enhancement module are proposed based on an improved automatic threshold logarithmic and enhancement algorithm. Combining the hardware and FPGA soft algorithm with excellent performance, the imaging results show that the system can get good color image effect of the ultra-low light level about 10-2lx.