NextStep-1: Unified Multi-modal Generation

This document introduces NextStep-1, a novel autoregressive model designed for text-to-image generation and image editing. Unlike prior models that heavily rely on diffusion, NextStep-1 directly generates images piece-by-piece using a Transformer backbone and a lightweight flow matching head for continuous image tokens. The research emphasizes the importance of a robust image tokenizer with channel-wise normalization to ensure stable training and mitigate artifacts, especially under strong guidance. The authors demonstrate that the Transformer's autoregressive process is the primary driver of image generation, with the flow matching head serving as a simple sampler. NextStep-1 shows competitive performance on various benchmarks, highlighting its advanced compositional abilities, linguistic understanding, and world knowledge integration.