Naturalness Preserved Enhancement Algorithm for Non-Uniform Illumination Images
Naturalness Preserved Enhancement Algorithm for Non-Uniform Illumination Images
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DOI：
10.1109/tip.2013.2261309
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发表时间：
2013-09-01
影响因子：
10.6
通讯作者：
Li, Bo
中科院分区：
文献类型：
--
作者：
Wang, Shuhang;Zheng, Jin;Li, Bo
图像增强在图像处理和分析中起着重要的作用。在众多的图像增强算法中，基于Retinex的图像增强算法能够有效地增强图像的细节，并得到了广泛的应用。由于基于Retinex的算法将光照去除视为默认偏好，并且没有限制反射率的范围，因此不能有效地保持非均匀光照图像的自然度。然而，自然是必不可少的图像增强，以达到令人愉快的感知质量。为了在增强细节的同时保持图像的自然度，提出了一种非均匀光照图像的增强算法。总的来说，本文做出了以下三大贡献。首先，提出了一种客观评价自然度保持的亮度阶差测度。其次，提出了一种亮通滤波器，将图像分解为反射率和光照，这两个部分分别决定了图像的细节和自然度。第三，我们提出了一个双对数变换，这是用来映射光照，使细节和自然之间的平衡。实验结果表明，该算法不仅可以增强非均匀光照图像的细节，而且可以保持图像的自然性。
Image enhancement plays an important role in image processing and analysis. Among various enhancement algorithms, Retinex-based algorithms can efficiently enhance details and have been widely adopted. Since Retinex-based algorithms regard illumination removal as a default preference and fail to limit the range of reflectance, the naturalness of non-uniform illumination images cannot be effectively preserved. However, naturalness is essential for image enhancement to achieve pleasing perceptual quality. In order to preserve naturalness while enhancing details, we propose an enhancement algorithm for non-uniform illumination images. In general, this paper makes the following three major contributions. First, a lightness-order-error measure is proposed to access naturalness preservation objectively. Second, a bright-pass filter is proposed to decompose an image into reflectance and illumination, which, respectively, determine the details and the naturalness of the image. Third, we propose a bi-log transformation, which is utilized to map the illumination to make a balance between details and naturalness. Experimental results demonstrate that the proposed algorithm can not only enhance the details but also preserve the naturalness for non-uniform illumination images.