基于改进秩一先验的图像去雾算法及其FPGA实现

Image dehazing algorithm and FPGA implementation via improved rank-one prior

  • 摘要: 图像去雾算法能够将雾霾环境下采集到的低质图像还原为清晰图像,但随着图像分辨率的增加和算法复杂度的提高,实际应用中算法的实时性难以保证。针对这一问题,研究并改进了一种复杂度低的秩一先验(rank-one prior, ROP)算法,并通过可编程门阵列(field programmable gate array,FPGA)硬件平台提高算法执行效率。首先利用FPGA并行处理优势,通过引入空间相关性与暗通道先验的约束,排除近景与高亮区域的干扰;再通过优化散射率图的估计方法,解决了原ROP算法复原后图像中的伪影问题,同时减少硬件资源的占用;最后根据估计的环境光值与散射率图求解,得到去雾后的清晰图像。实验结果表明,本文改进的算法能够提升雾霾和水下等散射场景图像的观感,复原结果图像色彩更加真实、细节更多。将该算法搭载在ZYNQ7020开发板(21 K个逻辑门资源、28.9%块存储器资源),处理1080 pixel图像用时54 ms,实现了实时性处理的需求,在自动驾驶、深海探测等领域具有广泛应用。

     

    Abstract: The image dehazing algorithm restores low-quality images captured in hazy environments to clear images. However, with the increase in image resolution and algorithm complexity, it is challenging to ensure the real-time performance of the algorithm in practical applications. To address this issue, this paper studies and improves a low-complexity ROP (rank-one prior) algorithm and enhances its execution efficiency through an FPGA(field programmable gate array) hardware platform. Firstly, leveraging the parallel processing advantages of FPGA, the algorithm incorporates spatial correlation and dark channel prior constraints to eliminate interference from close-range and high-brightness areas. By optimizing the scattering rate map estimation method, the improved algorithm resolves the artifacts present in images restored by the original ROP algorithm while reducing hardware resource consumption. Finally, the clear image is obtained by solving the estimated ambient light value and scattering rate map. Experimental results demonstrate that the improved algorithm enhances the visual quality of images in scattering scenes such as fog and underwater environments. The restored images exhibit more realistic colors and more details. Implementing this algorithm on the ZYNQ7020 development board (utilizing 21K LUT and 28.9% BRAM resources) processes 1080p images in 54 ms, meeting real-time processing requirements. This has broad applications in fields like autonomous driving and deep-sea exploration.

     

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