Minimalist and High-Performance Semantic Segmentation with Plain Vision Transformers

TL;DR

This paper introduces PlainSeg, a minimalist yet high-performance semantic segmentation model using plain Vision Transformers, emphasizing simplicity, high-resolution features, and hierarchical features for improved efficiency and effectiveness.

Contribution

The paper presents PlainSeg, a simple, efficient baseline for semantic segmentation with plain ViTs, and provides insights into high-resolution features and hierarchical feature utilization.

Findings

PlainSeg achieves competitive performance on multiple benchmarks.

High-resolution features are key to high performance with simple up-sampling.

Hierarchical features further improve segmentation accuracy.

Abstract

In the wake of Masked Image Modeling (MIM), a diverse range of plain, non-hierarchical Vision Transformer (ViT) models have been pre-trained with extensive datasets, offering new paradigms and significant potential for semantic segmentation. Current state-of-the-art systems incorporate numerous inductive biases and employ cumbersome decoders. Building upon the original motivations of plain ViTs, which are simplicity and generality, we explore high-performance `minimalist' systems to this end. Our primary purpose is to provide simple and efficient baselines for practical semantic segmentation with plain ViTs. Specifically, we first explore the feasibility and methodology for achieving high-performance semantic segmentation using the last feature map. As a result, we introduce the PlainSeg, a model comprising only three 3$\times$3 convolutions in addition to the transformer layers (either encoder or decoder). In this process, we offer insights into two underlying principles: (i) high-resolution features are crucial to high performance in spite of employing simple up-sampling techniques and (ii) the slim transformer decoder requires a much larger learning rate than the wide transformer decoder. On this basis, we further present the PlainSeg-Hier, which allows for the utilization of hierarchical features. Extensive experiments on four popular benchmarks demonstrate the high performance and efficiency of our methods. They can also serve as powerful tools for assessing the transfer ability of base models in semantic segmentation. Code is available at \url{https://github.com/ydhongHIT/PlainSeg}.