/v1/images/edits and /v1/images/variations take model, image and, for
edits, prompt as form fields. OpenAI SDKs work against the application base URL
unchanged.
Which registries can serve it
OpenAI, Azure OpenAI, OpenRouter and OpenAI-compatible endpoints expose an images API. Anthropic, Gemini and Vertex, Bedrock, Mistral, Groq, xAI and Cohere do not, and are left out of the pool. Gemini’s native Imagen API is a different surface and not covered; so are images inside chat messages.How it routes
Same as every capability: narrow to images-capable registries, then routing runs on that pool. Pinning a registry that cannot generate images is a400; an empty pool is a 503.
For multipart requests the gateway reads the form model field to apply the
application’s model restrictions and to resolve Azure deployment names — and
forwards the body as-is. It never rewrites multipart.