Gemini 3.1 Flash Lite Image parameters

Lite accepts the shared Gemini-native body and one output size. Keep imageSize uppercase when it is present.

Field	Value for this model
Model path	`gemini-3.1-flash-lite-image`
`responseModalities`	Include `IMAGE`; `TEXT` is optional
`aspectRatio`	Optional; YingTu verified `1:1`
`imageSize`	Omit or use `1K`
`2K` / `4K`	Unsupported
`candidateCount`	Omit or use `1`
YingTu price	USD 0.025 per request

{
  "contents": [{
    "role": "user",
    "parts": [{"text": "A clean product thumbnail with a single object"}]
  }],
  "generationConfig": {
    "responseModalities": ["TEXT", "IMAGE"],
    "imageConfig": {"aspectRatio": "1:1", "imageSize": "1K"}
  }
}

Fast editing input

The upstream model is designed for local edits such as color swaps, stickers, and background changes. YingTu verified the same inline input shape used by the rest of the family:

{
  "contents": [{
    "role": "user",
    "parts": [
      {"text": "Preserve the object and change only the surface color"},
      {"inlineData": {"mimeType": "image/png", "data": "BASE64_SOURCE_IMAGE"}}
    ]
  }],
  "generationConfig": {
    "responseModalities": ["TEXT", "IMAGE"],
    "imageConfig": {"aspectRatio": "1:1", "imageSize": "1K"}
  }
}

imageSize is case-sensitive. Use 1K, not 1k or 1024px.

The verified responses contained one candidate with role: "model" and PNG data. Always treat the returned mimeType as authoritative.

​Fast editing input

Fast editing input