水下距离选通图像双平台直方图增强及其FPGA实时处理

Underwater Range Gated Image Enhancement Based on Double Platform Histogram Equalization and FPGA Real-time Processing

水下激光距离选通成像中要对水下距离选通图像进行增强处理。水下图像通常具有噪声大、对比度差、照度不均匀的特点。通过分析水下图像的成像特点,针对引起图像降质的因素进行增强算法设计,提出了基于帧叠加去噪与双平台直方图变换相结合的视频增强算法。可实现目标信息增强的同时抑制背景,将目标和背景区别处理。算法以Xilinx公司的XC5VLX50T系列FPGA芯片为核心,使用到了软核Microblaze、片内BLOCKRAM、外部SRAM等资源设计硬件系统,并已在水下选通成像系统中得到有效应用。

The images of underwater range gated system always have a few problems like uneven lighting, low contrast and noises. In order to improve the quality of those kinds of images, this paper put forward an algorithm based on image frames superimpose and double platform histogram equalization. The algorithm not only enhances the target information but also suppresses the enhancement of the background. The design of algorithm is based on the FPGA chip produced by Xilinx company, which uses hardware resources including Microblaze, BLOCKRAM, SRAM and so on. The algorithm has been proved effective in the underwater range gated system.