ByteDance Seed launches Seedream 5.5 with 100-round edit stability and RGBA transparency

ByteDance Seed introduced Seedream 5.5 on 9 November 2026, upgrading its flagship image generation and editing model for commercial design pipelines. Standard diffusion editors gradually drift in colour, facial identity and background geometry after several conversational revisions; Seedream 5.5 constrains latent updates to edited regions so unmasked pixels remain stable across up to 100 sequential editing rounds. The model also outputs native four-channel RGBA images with clean alpha transparency around hair, glass and UI stickers without requiring a separate background-removal pass.

Realism and commercial evaluations

To reduce synthetic skin sheen and garbled signage, ByteDance Seed retrained the model’s layout and texture stages for dense Chinese and English typography as well as natural lens grain. On Good-Same-Bad (GSB) human preference evaluations published by the team, Seedream 5.5 outperforms GPT Image 2.5 Sunburst, Google’s Nano Banana 2.1 and Seedream 5.0 Pro on text-to-image realism and bilingual text structure, with only image-to-image realism against Nano Banana 2.1 (-6.18%) favouring the rival model. Seedream 5.5 is rolling out across Jimeng, Doubao, Doubao Work and enterprise API platform Volcano Ark; ByteDance Seed did not disclose international per-image API pricing in the blog post.