提出三分支可逆模块,提升图像缩放的重建质量与效率。
Plug-and-Play Tri-Branch Invertible Block for Image Rescaling
- 将低频信息分解为亮度和色度,减少通道冗余。
- 上采样时对高频分量采用全零映射,聚焦关键信息。
- 可即插即用,适用于通用缩放与有损压缩场景。
高分辨率(HR)图像常被下采样至低分辨率(LR)以降低带宽,随后再上采样恢复原始细节。近期图像缩放算法采用可逆神经网络(INNs)构建统一框架,确保LR与HR图像间的一一对应关系。传统双分支方法分别处理高频与低频信息,常依赖特定分布建模高频成分,而直接在RGB域处理低频分量会引入通道冗余,限制重建效率。为此,我们提出即插即用的三分支可逆块(T-InvBlocks),将低频分支分解为亮度(Y)与色度(CbCr)分量,降低冗余并增强特征处理能力;同时在上采样阶段对高频分量采用全零映射策略,使关键缩放信息集中于LR图像中。T-InvBlocks可无缝集成至现有缩放模型,显著提升通用缩放任务及有损压缩场景下的性能。大量实验验证了该方法在高分辨率图像重建上的先进性。
原文摘要 · Abstract (English)
High-resolution (HR) images are commonly downscaled to low-resolution (LR) to reduce bandwidth, followed by upscaling to restore their original details. Recent advancements in image rescaling algorithms have employed invertible neural networks (INNs) to create a unified framework for downscaling and upscaling, ensuring a one-to-one mapping between LR and HR images. Traditional methods, utilizing dual-branch based vanilla invertible blocks, process high-frequency and low-frequency information separately, often relying on specific distributions to model high-frequency components. However, processing the low-frequency component directly in the RGB domain introduces channel redundancy, limiting the efficiency of image reconstruction. To address these challenges, we propose a plug-and-play tri-branch invertible block (T-InvBlocks) that decomposes the low-frequency branch into luminance (Y) and chrominance (CbCr) components, reducing redundancy and enhancing feature processing. Additionally, we adopt an all-zero mapping strategy for high-frequency components during upscaling, focusing essential rescaling information within the LR image. Our T-InvBlocks can be seamlessly integrated into existing rescaling models, improving performance in both general rescaling tasks and scenarios involving lossy compression. Extensive experiments confirm that our method advances the state of the art in HR image reconstruction.
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