The evolution of semantic segmentation has long been dominated by learning
more discriminative image representations for classifying each pixel. Despite
the prominent advancements, the priors of segmentation masks themselves, e.g.,
geometric and semantic constraints, are still under-explored. In this paper, we
propose to ameliorate the semantic segmentation quality of existing
discriminative approaches with a mask prior modeled by a recently-developed
denoising diffusion generative model. Beginning with a unified architecture
that adapts diffusion models for mask prior modeling, we focus this work on a
specific instantiation with discrete diffusion and identify a variety of key
design choices for its successful application. Our exploratory analysis
revealed several important findings, including: (1) a simple integration of
diffusion models into semantic segmentation is not sufficient, and a
poorly-designed diffusion process might lead to degradation in segmentation
performance; (2) during the training, the object to which noise is added is
more important than the type of noise; (3) during the inference, the strict
diffusion denoising scheme may not be essential and can be relaxed to a simpler
scheme that even works better. We evaluate the proposed prior modeling with
several off-the-shelf segmentors, and our experimental results on ADE20K and
Cityscapes demonstrate that our approach could achieve competitively
quantitative performance and more appealing visual quality.

本文中，我们提出了使用最近发展的去噪扩散生成模型建模的掩模先验来提高现有判别方法的语义分割质量。我们发现简单的集成扩散模型到语义分割中是不够的，并且一次差的扩散过程设计可能导致分割性能下降。我们通过多个实验表明，我们的方法在 ADE20K 和 Cityscapes 数据集上达到了较高的定量和定性性能。