用方向梯度直方图提升图像修复的泛化能力
Gradient as Conditions: Rethinking HOG for All-in-one Image Restoration
- 引入可学习的HOG特征作为退化条件,指导修复过程
- 在多个基准上达到当前最优,复杂场景泛化性强
- 适合需要鲁棒性与可解释性的图像修复任务
全功能图像修复(AIR)旨在通过信息丰富的退化条件,在统一模型中处理多种退化问题。现有方法多依赖隐式学习的先验,易导致特征混淆,影响复杂或未见场景下的表现。我们发现方向梯度直方图(HOG)在不同退化间具有强区分能力,是理想的可解释先验。为此提出HOGformer,一种基于Transformer的模型,融合可学习的HOG特征实现退化感知修复。核心为动态HOG感知自注意力(DHOGSA),根据HOG编码的退化线索自适应建模长程空间依赖;另设计动态交互前馈(DIFF)模块,增强通道-空间交互,提升多样性退化下的特征变换能力。此外,引入HOG损失以显式增强结构保真度与边缘锐度。在多种基准(含恶劣天气与自然退化)上的大量实验表明,HOGformer性能领先且在复杂真实场景中泛化良好。代码已开源。
原文摘要 · Abstract (English)
All-in-one image restoration (AIR) aims to address diverse degradations within a unified model by leveraging informative degradation conditions to guide the restoration process. However, existing methods often rely on implicitly learned priors, which may entangle feature representations and hinder performance in complex or unseen scenarios. Histogram of Oriented Gradients (HOG) as a classical gradient representation, we observe that it has strong discriminative capability across diverse degradations, making it a powerful and interpretable prior for AIR. Based on this insight, we propose HOGformer, a Transformer-based model that integrates learnable HOG features for degradation-aware restoration. The core of HOGformer is a Dynamic HOG-aware Self-Attention (DHOGSA) mechanism, which adaptively models long-range spatial dependencies conditioned on degradation-specific cues encoded by HOG descriptors. To further adapt the heterogeneity of degradations in AIR, we propose a Dynamic Interaction Feed-Forward (DIFF) module that facilitates channel-spatial interactions, enabling robust feature transformation under diverse degradations. Besides, we propose a HOG loss to explicitly enhance structural fidelity and edge sharpness. Extensive experiments on a variety of benchmarks, including adverse weather and natural degradations, demonstrate that HOGformer achieves state-of-the-art performance and generalizes well to complex real-world scenarios.Code is available at https://github.com/Fire-friend/HOGformer.
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