空间摄像机高速滤波器的并行结构设计与实现

发布时间：2018-04-05 17:33

本文选题：空间摄像机　切入点：图像滤波　出处：《西安电子科技大学》2015年硕士论文

【摘要】：空间摄像机是空间环境监测、设备监视以及科学实验平台的重要组成部分。近年来,随着航天技术的飞速发展以及对空问探索可视化的要求越来越高,空间摄像机在航天飞行器中得到了广泛的应用。它可以协助飞船与空间站进行准确对接,也可以监控各种太空飞行器的运转。空间摄像机常工作于具有微重力、极端温度环境、强辐射和低照度拍摄等特点的太空环境中,应用于空间摄像机的图像处理面临严峻挑战。本课题来源于航天高清摄像机的高速图像处理需求。航天飞行器中,用于科学实验和设备监测的高清摄像机通常在光线较弱的情况下进行拍摄,因而在图像的采集和传输的过程中,不可避免的会引入很大的噪声。这些噪声不仅影响图像的主观观测质量,同时严重影响视频编码系统的性能。高速图像滤波可以在去除图像中噪声的同时,有效的保护好图像的细节纹理信息,因此是航天视频压缩系统的必要部分。本文围绕空间摄像机高清视频的去噪问题,做了以下工作：1.对图像滤波算法进行了归类,深入分析了各种滤波算法的优缺点,以及在高速硬件实现时存在的问题。通过综合比较和分析,选取了同时满足处理速度和资源占用率要求的滤波算法来实现空问摄像机高清视频的实时滤波处理。2.由于FPGA不适用于进行权值的浮点计算,针对空间距离权重的计算,采用DSP对参数固定的空间距离权重进行浮点型计算,在进行整数化、归一化后通过EMIF口向FPGA传递。针对相似度权重的计算,对常见噪声范围分析后选取了五种参数,对所有像素值的相似权重进行计算,分别写入五个不同的ROM中,计算时通过查找ROM获得,ROM的选择由DSP端通过EMIF口进行控制。利用FPGA强大的并行计算特点设计了双边滤波的硬件架构设计,对像素进行流水线操作,实现了平均每个时钟完成一个像素的所有运算的高速处理。硬件架构设计中针对像素的缓存与读取设计了状态机进行循环存储和循环读取。滤波参数的传递统一采用EMIF口完成。通过仿真验证了该算法实现的正确性,并在硬件上完成了该设计的验证。实际工程应用的结果表明,本文所设计的双边滤波在占用资源较少的情况下,可以实现空问摄像机高清视频的实时滤波。3.对空间摄像机拍摄的低照度照片进行硬件滤波,从主观质量评价和客观质量评价两个方面对滤波的效果进行评价,评价结果均表明基于硬件的双边滤波取得了良好的滤波效果。
[Abstract]:Space camera is an important part of space environment monitoring, equipment monitoring and scientific experiment platform.In recent years, with the rapid development of space technology and the higher and higher requirements of space exploration visualization, space cameras have been widely used in space vehicles.It can help the spacecraft docking with the space station accurately, but also can monitor the operation of various space vehicles.Space cameras often work in space environments with the characteristics of microgravity, extreme temperature, strong radiation and low illumination, etc. The application of space cameras in image processing is faced with severe challenges.This topic comes from the demand of high-speed image processing of high-definition space camera.In aerospace vehicles, high-definition cameras used in scientific experiments and equipment monitoring are usually captured in the case of weak light. Therefore, in the process of image acquisition and transmission, it is inevitable to introduce a lot of noise.These noises not only affect the subjective observation quality of images, but also seriously affect the performance of video coding systems.High-speed image filtering can effectively protect the detailed texture information of the image while removing the noise in the image, so it is an essential part of the space video compression system.In this paper, the problem of space camera HD video denoising, do the following work: 1.The image filtering algorithms are classified, and the advantages and disadvantages of various filtering algorithms are analyzed, as well as the problems in high-speed hardware implementation.Through comprehensive comparison and analysis, the filtering algorithm which meets the requirements of processing speed and resource occupancy is selected to realize the real-time filtering processing of high-definition video of aerial camera.Because FPGA is not suitable for floating point calculation of weight value, DSP is used to calculate the weight of space distance with fixed parameters by using DSP to calculate the weight of space distance. After the integer is carried out, the weight is transferred to FPGA through the EMIF port after normalization.For the calculation of similarity weight, five parameters are selected after analyzing the common noise range, and the similar weights of all pixel values are calculated and written into five different ROM, respectively.The choice of ROM is controlled by DSP port through EMIF port.Based on the powerful parallel computing characteristics of FPGA, the hardware architecture of two-sided filtering is designed. Pipeline is used to operate the pixels, and the high speed processing of each pixel is realized on average.In the design of hardware architecture, the state machine is designed for the storage and reading of pixels.The transmission of filtering parameters is unified by EMIF port.The correctness of the algorithm is verified by simulation, and the design is verified in hardware.The results of practical engineering application show that the designed two-sided filter can realize real-time filtering of high-definition video of aerial camera with less resources.In this paper, the low illuminance image taken by space camera is filtered by hardware, and the effect of the filter is evaluated from two aspects: subjective quality evaluation and objective quality evaluation. The evaluation results show that the hardware based bilateral filter has good filtering effect.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V447;TN713

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