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Overview

The Image Generation action creates PNG images from your prompt. You can also attach an image and ask Onyx to edit or extend it. Image Generation Image Generation is available in all editions. It does not appear in the actions menu until an admin connects a provider.

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Supported models

Onyx supports image models from OpenAI, Azure OpenAI, and Google Cloud Vertex AI: The GPT Image 2.5 models give the best prompt control and the most reliable in-image text. Gemini 2.5 Flash Image is fast and good for quick creative exploration. Gemini 3 Pro Image gives high-fidelity output for complex, detailed visuals.
Older models such as GPT Image 1 stay visible only while they are still connected. New connections cannot select them.

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Usage

An admin connects a provider and selects the default model at Admin Panel → Image Generation. After setup, the LLM can use Image Generation in any chat or custom Agent that has the action enabled. To force or block it for one chat, open the actions menu in the input bar and toggle Image Generation.
Be explicit when you want an image. For example: “Generate an image of …” or “Edit the attached image to …”.
For setup details, see the admin configuration guide.