提出新色彩空间与网络,解决极暗环境下图像增强的色彩失真和噪点问题。
HVI-CIDNet+: Beyond Extreme Darkness for Low-Light Image Enhancement
- 设计新型HVI色彩空间,分离亮度与颜色,抑制红黑噪点。
- 引入先验引导注意力机制,提升极暗区域内容恢复与色彩校正精度。
- 适用于极端低光场景,适合图像增强与摄影修复领域研究者。
低光图像增强(LLIE)旨在从受损的低光图像中恢复生动内容与细节。现有基于标准RGB(sRGB)色彩空间的方法常因高色度敏感性导致色彩偏移和亮度伪影。尽管色调、饱和度、明度(HSV)色彩空间可解耦亮度与颜色,但会引入显著的红噪与黑噪。为此,本文提出一种面向LLIE的新色彩空间——水平/垂直-明度(HVI),由HV色彩图与可学习明度构成。HV色彩图通过约束红色坐标间距离以消除红噪,可学习明度则压缩低光区域以去除黑噪。此外,提出基于HVI色彩空间的色彩与亮度解耦网络+(HVI-CIDNet+),用于恢复受损内容并缓解极暗区域的色彩畸变。具体地,HVI-CIDNet+利用预训练视觉语言模型从低光图像中提取丰富上下文与退化知识,通过新型先验引导注意力块(PAB)融合。在PAB中,潜在语义先验促进内容恢复,退化表示指导精确色彩校正,尤其在极暗区域通过精心设计的交叉注意力融合机制实现。同时,构建区域精修模块,对信息丰富区域采用卷积,对信息匮乏区域采用自注意力,确保亮度调整准确。基准实验在10个数据集上的全面结果表明,所提HVI-CIDNet+优于当前最先进方法。
原文摘要 · Abstract (English)
Low-Light Image Enhancement (LLIE) aims to restore vivid content and details from corrupted low-light images. However, existing standard RGB (sRGB) color space-based LLIE methods often produce color bias and brightness artifacts due to the inherent high color sensitivity. While Hue, Saturation, and Value (HSV) color space can decouple brightness and color, it introduces significant red and black noise artifacts. To address this problem, we propose a new color space for LLIE, namely Horizontal/Vertical-Intensity (HVI), defined by the HV color map and learnable intensity. The HV color map enforces small distances for the red coordinates to remove red noise artifacts, while the learnable intensity compresses the low-light regions to remove black noise artifacts. Additionally, we introduce the Color and Intensity Decoupling Network+ (HVI-CIDNet+), built upon the HVI color space, to restore damaged content and mitigate color distortion in extremely dark regions. Specifically, HVI-CIDNet+ leverages abundant contextual and degraded knowledge extracted from low-light images using pre-trained vision-language models, integrated via a novel Prior-guided Attention Block (PAB). Within the PAB, latent semantic priors can promote content restoration, while degraded representations guide precise color correction, both particularly in extremely dark regions through the meticulously designed cross-attention fusion mechanism. Furthermore, we construct a Region Refinement Block that employs convolution for information-rich regions and self-attention for information-scarce regions, ensuring accurate brightness adjustments. Comprehensive results from benchmark experiments demonstrate that the proposed HVI-CIDNet+ outperforms the state-of-the-art methods on 10 datasets.
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