用少步生成模型实现高效有损压缩,无需重新训练。
Few-step Generative Models as Lossy Compression

- 将少步生成模型映射到反向信道编码框架,构建新压缩方法。
- 在低比特率下编码解码更快,图像真实感提升显著。
- 适用于需快速生成的场景,如实时视频传输与存储优化。
DiffC为复用预训练扩散模型进行有损压缩提供了理论依据,但其编码和解码过程仍因需大量离散正向与逆向步骤而缓慢。本文研究是否可将少步生成模型——修正流(Rectified Flow)、一致性轨迹模型(CTM)和均值流(MeanFlow)——纳入相同的反向信道编码(RCC)框架作为编解码器。主要挑战在于RCC需要后验分布和共享分布参数,而这些模型并未显式参数化中间条件分布。对于修正流和均值流,我们利用速度参数化与扩散去噪参数化的等价性,推导出RCC所需量;对于从EDM蒸馏得到的CTM,采用EDM噪声参数化,并结合中间状态上发送方与共享分布的局部高斯近似。这带来了首个概念验证的概率形式,使得无需再训练即可使用预训练的少步生成模型进行压缩。在低分辨率基准测试中,所得编解码器显著降低编码解码时间,并在低比特率下提升图像真实感。
原文摘要 · Abstract (English)
DiffC provides a principled way to reuse pre-trained diffusion models for lossy compression, but its encoding and decoding procedures remain slow because they require many discretized forward and reverse steps. We study whether few-step generative models -- Rectified Flow, Consistency Trajectory Models (CTM), and MeanFlow -- can be cast as codecs within the same reverse channel coding (RCC) framework. The main challenge is that RCC requires posterior and shared distribution parameters, whereas these models do not explicitly parameterize intermediate conditional distributions. For Rectified Flow and MeanFlow, we use the equivalence between velocity parameterization and diffusion-style denoising parameterization to derive the quantities required by RCC. For CTM, which is distilled from EDM, we adopt the EDM noise parameterization together with local Gaussian approximations of the sender and shared distributions at intermediate states. This yields a proof-of-concept probabilistic formulation that enables compression with pre-trained few-step generative models without retraining. On low-resolution benchmarks, the resulting codecs reduce encoding and decoding time and improve realism in the low-bit-rate regime.
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