GPT-Image-2.5 (Sunburst) vs Union Alpha (Stealth)
A direct, empirical evaluation of GPT-Image-2.5 (Sunburst) (OpenAI) against Union Alpha (Stealth) (OpenRouter & OpenCode).
GPT-Image-2.5 (Sunburst)
Developed by OpenAI · Proprietary Multimodal DiT parameters
High-fidelity typographic rendering, raytracing reflection accuracy, sketch-to-image conditioning, and localized comment inpainting.
Union Alpha (Stealth)
Developed by OpenRouter & OpenCode · Multi-Model Ensemble Mixture parameters
Terminal coding agents, pull-request synthesis, multi-model consensus verification, and zero-cost autonomous refactoring.
| Metric | GPT-Image-2.5 (Sunburst) | Union Alpha (Stealth) |
|---|---|---|
| SWE-bench Verified | 62.4% | 74.2% |
| MMLU-Pro | 89.5% | 89.8% |
| MATH-500 | 91.2% | 95.4% |
| Context Window | Spatial Vector Token Canvas (1792×1024) | 256,000 tokens |
| Input Pricing (per 1M) | $2.50 | $0.00 |
| Output Pricing (per 1M) | $10.00 | $0.00 |