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arXiv 2606.01608cs.CV

利用语义和像素表示进行超低比特率图像压缩

Exploiting Semantic and Pixel Representations for Ultra-Low Bitrate Image Compression

National Key Laboratory of Human-Machine Hybrid Augmented Intelligence, Institute of Artificial Intelligence and Robotics, Xi’an Jiaotong University(人机混合增强智能国家重点实验室,人工智能与机器人研究院,西安交通大学);School of Information and Telecommunication, Xi’an Jiaotong University(信息与电信学院,西安交通大学);Department of Computer Science and Software Engineering, The University of Western Australia(计算机科学与软件工程系,西澳大学)

Hao Wei, Yanhui Zhou, Chenyang Ge, Saeed Anwar, Ajmal Mian

AI总结:

提出SPRDiff扩散压缩方法,通过三重编码器架构和失真感知重建模块,在超低比特率下同时保持语义一致性和像素级保真度,实现率-失真-感知权衡最优。

摘要:

大多数现有的极端压缩方法未能实现最优的率-失真-感知权衡,因为它们通常优先考虑感知保真度和视觉真实性而非像素级精度。因此,重建结果往往与原始图像有明显偏差。超低比特率图像压缩因此至关重要——不仅要产生极其紧凑的表示,还要确保重建图像在语义上与源图像保持一致,并在像素级忠实于源图像。为此,我们提出了SPRDiff,一种基于扩散的压缩方法,充分利用语义和像素表示,从而在超低比特率约束下增强重建保真度。具体来说,我们开发了一个三重编码器架构,利用预训练的面向失真和面向语义编码器的高保真特征来补偿冻结的VAE编码器提取的有限表示,从而改善潜在压缩和熵建模。为了进一步提高扩散模型的重建保真度,我们引入了一个具有双特征提取的失真感知重建模块。该模块不仅生成保留主要结构的粗略重建,还提供实用且准确的语义级和像素级条件信号来指导扩散模型。在基准数据集上的大量实验表明,我们的方法在极低比特率(低于0.03 bpp)下在率-失真-感知权衡方面优于最先进的方法,有效保持了重建图像中的感知质量和像素级保真度。我们将在https://github.com/cshw2021/SPRDiff发布源代码和训练模型。

英文摘要:

Most existing extreme compression methods fail to achieve an optimal rate-distortion-perception trade-off, as they typically prioritize perceptual fidelity and visual realism over pixel-level accuracy. Consequently, the resulting reconstructions often deviate noticeably from the originals. Ultra-low bitrate image compression is therefore crucial-not only for producing extremely compact representations but also for ensuring that reconstructed images remain semantically coherent and faithful to the source at the pixel level. To this end, we propose SPRDiff, a diffusion-based compression method that fully leverages both semantic and pixel representations, thereby enhancing reconstruction fidelity under ultra-low bitrate constraints. Specifically, we develop a triple-encoder architecture that utilizes high-fidelity features from the pretrained distortion-oriented and semantic-oriented encoders to compensate for the limited representations extracted by the frozen VAE encoder, thereby improving latent compression and entropy modeling. To further enhance the reconstruction fidelity of diffusion models, we introduce a distortion-aware reconstruction module with dual feature extraction. This module not only generates a coarse reconstruction that preserves the main structures, but also provides practical and accurate semantic- and pixel-level conditional signals to guide the diffusion model. Extensive experiments on benchmark datasets demonstrate that our method outperforms state-of-the-art approaches in the rate-distortion-perception tradeoff at extremely low bitrates (below 0.03 bpp), effectively preserving both perceptual quality and pixel-wise fidelity in the reconstructed images. We will release the source code and trained models at https://github.com/cshw2021/SPRDiff.

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