基于改进Otsu和双直方图均衡化的红外图像增强算法

Infrared Image Enhancement Algorithm Based on Improved Otsu and Dual Histogram Equalization

  • 摘要: 由于红外图像增强算法中存在欠增强、过增强、边缘细节增强效果差等缺陷,为在改善红外图像视觉效果、突出图像细节信息的同时避免上述缺陷,本文提出Otsu算法和双区域直方图均衡结合的红外图像的增强算法。首先基于教与学搜索策略和精英反向学习策略改进布谷鸟算法,以搜索到图像最优分割阈值。然后基于Otsu算法将红外图像分割为前景区域和背景区域。最后分别对前景区域进行局部直方图均衡化增强,对背景区域使用限制对比度直方图均衡化增强,并将两区域拼接得到增强图像。本文基于FLIR红外数据集进行实验,并与传统直方图均衡、双直方图均衡、限制对比度的自适应直方图均衡和现有基于K-Means算法的双直方图均衡四种算法相比较。实验结果表明,本文算法增强结果在主观上视觉效果更佳,且增强后两幅图像的信息熵、平均梯度、峰值信噪比和空间频率4个性能指标的平均值相较于原图像分别提升了1.2396、2.6046、7.1581和6.3042。最后使用4个基准函数对本文改进布谷鸟搜索算法性能进行检测,对于不同特征的基准函数,本文算法收敛速度与求解精度都有提升。综上,本文算法在红外图像增强领域具有一定优势。

     

    Abstract: Due to the shortcomings of under- and over-enhancement and poor enhancement of edge details in infrared image enhancement algorithms, we propose an infrared image enhancement algorithm that combines Otsu's algorithm and dual region histogram equalization to improve the visual effect of infrared images, highlight image detail information, and avoid the abovementioned shortcomings. Firstly, based on a teaching and learning search strategy and the elite reverse learning strategy, the cuckoo algorithm is improved to search for the optimal segmentation threshold of the image. Then, the infrared image is segmented into foreground and background regions based on Otsu's algorithm. Finally, local histogram equalization enhancement is applied to the foreground region, and contrast limited histogram equalization enhancement is used to the background region. The two regions are concatenated to obtain an enhanced image. We conducted experiments based on the FLIR infrared dataset and compared them with four algorithms, including traditional histogram equalization, dual histogram equalization, adaptive histogram equalization with limited contrast, and existing dual histogram equalization based on k-means clustering. The experimental results show that the proposed algorithm has better subjective visual effects, and the average performance indicators of information entropy, average gradient, peak signal-to-noise ratio, and spatial frequency of two images after enhancement increased by 1.2396, 2.6046, 7.1581, and 6.3042 respectively compared to the original images. Finally, 4 benchmark functions were used to test the performance of the improved cuckoo algorithm. For benchmark functions with different features, the convergence speed and solution accuracy of the proposed algorithm were significantly improved. Overall, this algorithm exhibited certain advantages in the field of infrared image enhancement.

     

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