Abstract
Ultra-High-Definition (UHD) photo has gradually become the standard configuration in advanced imaging devices. The new standard unveils many issues in existing approaches for low-light image enhancement (LLIE), especially in dealing with the intricate issue of joint luminance enhancement and noise removal while remaining efficient. Unlike existing methods that address the problem in the spatial domain, we propose a new solution, UHDFour, that embeds Fourier transform into a cascaded network. Our approach is motivated by a few unique characteristics in the Fourier domain: 1) most luminance information concentrates on amplitudes while noise is closely related to phases, and 2) a high-resolution image and its low-resolution version share similar amplitude patterns.Through embedding Fourier into our network, the amplitude and phase of a low-light image are separately processed to avoid amplifying noise when enhancing luminance. Besides, UHDFour is scalable to UHD images by implementing amplitude and phase enhancement under the low-resolution regime and then adjusting the high-resolution scale with few computations. We also contribute the first real UHD LLIE dataset, \textbf{UHD-LL}, that contains 2,150 low-noise/normal-clear 4K image pairs with diverse darkness and noise levels captured in different scenarios. With this dataset, we systematically analyze the performance of existing LLIE methods for processing UHD images and demonstrate the advantage of our solution. We believe our new framework, coupled with the dataset, would push the frontier of LLIE towards UHD. The code and dataset are available at this https URL.
Abstract (translated)
超高清(UHD)照片逐渐已经成为高端成像设备的标准配置。这个新标准揭示了现有方法中许多针对低光图像增强(LLIE)的问题,特别是在处理同时增强亮度和消除噪声的精细问题时,而仍然保持高效性方面的问题。与现有的方法在空间域解决问题不同,我们提出了一个新的解决方案,称为UHDFour,它将傅里叶变换嵌入到一个级联网络中。我们的方案受到一些傅里叶域独特的特性的启发:1)大部分亮度信息集中在幅度上,而噪声与相位密切相关;2)高分辨率图像和低分辨率版本具有相似的幅度模式。通过将傅里叶嵌入我们的网络中,我们对低光图像的幅度和相位分别进行处理,以避免在增强亮度时增加噪声。此外,UHDFour可以 scalable to UHD图像,通过在低分辨率模式下实施幅度和相位增强,然后微调高分辨率尺寸,而只需要很少的计算。我们还提供了第一个真实的UHD Llie数据集 extbf{UHD-LL},它包含2,150个低噪声/正常清晰的4K图像对,在不同场景中记录了不同的黑暗度和噪声水平。通过这个数据集,我们可以系统地分析现有LLIE方法处理UHD图像的性能,并展示我们解决方案的优势。我们认为,与我们的数据集结合使用,将推动Llie向UHD领域的前进。代码和数据集可在该httpsURL上获取。
URL
https://arxiv.org/abs/2302.11831
