Gemini 3.1 Flash Lite Image parameters

Use the full image model ID:

gemini-3.1-flash-lite-image

Do not shorten it to gemini-3.1-flash-lite; that identifies the text model.

Output controls

Field	Value through this API
`responseModalities`	Include `IMAGE`; `TEXT` is optional
`candidateCount`	Omit or use `1`
`imageSize`	Omit or use uppercase `1K`
`2K` / `4K`	Not supported
`aspectRatio`	Optional; choose one value below
Top-level `n` or `resolution`	Not supported

This API exposes these ten explicit ratios for Lite:

1:1   2:3   3:2   3:4   4:3
4:5   5:4   9:16  16:9  21:9

Google’s current model page says the model supports fourteen ratios but explicitly lists the same ten values above. YingTu documents the explicit values available in its current model-fixed form rather than guessing the other four.

Generation body

{
  "contents": [{
    "role": "user",
    "parts": [{"text": "A bright onboarding illustration for a mobile finance app"}]
  }],
  "generationConfig": {
    "responseModalities": ["TEXT", "IMAGE"],
    "imageConfig": {"aspectRatio": "9:16", "imageSize": "1K"},
    "candidateCount": 1
  }
}

Reference-image input

Add one or more source images after the instruction:

{
  "contents": [{
    "role": "user",
    "parts": [
      {"text": "Keep the layout and change the accent color to teal"},
      {
        "inlineData": {
          "mimeType": "image/png",
          "data": "BASE64_SOURCE_IMAGE_1"
        }
      },
      {"inlineData": {"mimeType": "image/jpeg", "data": "BASE64_SOURCE_IMAGE_2"}}
    ]
  }],
  "generationConfig": {
    "responseModalities": ["TEXT", "IMAGE"],
    "imageConfig": {"aspectRatio": "9:16", "imageSize": "1K"},
    "candidateCount": 1
  }
}

Unified asynchronous editing accepts 1–16 images, with a 20 MiB decoded limit per file and 64 MiB total. Synchronous multi-image behavior follows the current official Gemini model contract. A fixed maximum source-image byte or pixel size is not currently published. Total request-body, proxy, and upstream limits may differ; reduce the source image after HTTP 413, and contact API support before relying on a guaranteed production envelope.

Copy Lite examples

Run complete generation, asynchronous, editing, and parsing flows.

Compare the family

Choose Flash before the integration needs a higher output tier.

​Output controls

​Generation body

​Reference-image input

Copy Lite examples

Compare the family

Output controls

Generation body

Reference-image input