Gemini 3 Pro Image Preview

Model ID

gemini-3-pro-image-preview

Capability	Supported value
Text-to-image	Yes
Image-to-image	Yes
Multi-image reference	No
Aspect ratio (`aspect_ratio`)	`1:1`, `5:4`, `4:5`, `4:3`, `3:4`, `3:2`, `2:3`, `16:9`, `9:16`, `21:9`
`resolution`	Selected automatically by the model
`quality`	Selected automatically by the model; do not send
Reference field	`image`

Output count is limited by the model metadata returned for your account.

Field	Required	Notes
`model`	Yes	Must be `gemini-3-pro-image-preview`.
`prompt`	Yes	Text description or editing instruction.
`aspect_ratio`	No	Preferred aspect-ratio field; select one supported value listed above.
`size`	No	Compatibility alias for `aspect_ratio`. New integrations should use `aspect_ratio`.
`n`	No	Defaults to `1`; account/model limit comes from the model list API.
`image`	No	Single reference image URL for image-to-image generation.
`response_format`	No	`url` (default) or `b64_json`.
`output_format`	No	`png` or `jpeg`.
`wait_for_completion`	No	Defaults to `false`, which returns an asynchronous task ID. Set to `true` to wait in the create request.
`polling_timeout`	No	Polling timeout used only when `wait_for_completion` is `true`.

{
  "model": "gemini-3-pro-image-preview",
  "prompt": "Create a cinematic editorial image",
  "aspect_ratio": "21:9"
}