Skip to main content
Gemini 3.1 Flash Image is Google’s image generation model, available through Anyfast via the native Gemini API. It can generate images from text prompts and edit existing images using a reference photo.
Google released gemini-3.1-flash-image as the GA model for Nano Banana 2 on May 28, 2026. Use this stable model ID instead of gemini-3.1-flash-image-preview, which is deprecated and scheduled to shut down on June 25, 2026.

​
Key capabilities

  • Text-to-image — Generate images from text descriptions
  • Image editing — Pass a reference image in inline_data alongside your text instruction
  • Aspect ratio control — 1:1, 4:3, 3:4, 16:9, 9:16
  • Resolution control — 512 (512px), 1K (~1024px), 2K (~2048px), 4K (~4096px) on the long edge
  • Multi-modal output — Return both the image and a text caption with responseModalities: ["TEXT", "IMAGE"]
Note: If you need the generated image returned as a URL, select the Aggregate-NanoUrl group when creating your API token.

​
Text-to-image example

curl "https://www.anyfast.ai/v1beta/models/gemini-3.1-flash-image:generateContent?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [
          { "text": "Generate an image of a sunset over mountains" }
        ]
      }
    ],
    "generationConfig": {
      "responseModalities": ["TEXT", "IMAGE"],
      "imageConfig": {
        "aspectRatio": "16:9",
        "imageSize": "1K"
      }
    }
  }'

​
Image editing example (with reference image)

Include both a text instruction and an inline_data reference image in the same parts array. 
# First encode your image to base64:
# BASE64=$(base64 -i your_photo.jpg)
#
# Then send the request:
curl "https://www.anyfast.ai/v1beta/models/gemini-3.1-flash-image:generateContent?key=YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "contents": [
      {
        "role": "user",
        "parts": [
          {
            "text": "Hi, this is a picture of me. Can you add a llama next to me?"
          },
          {
            "inline_data": {
              "mime_type": "image/jpeg",
              "data": "<YOUR_BASE64_ENCODED_IMAGE>"
            }
          }
        ]
      }
    ],
    "generationConfig": {
      "responseModalities": ["TEXT", "IMAGE"],
      "imageConfig": {
        "aspectRatio": "1:1",
        "imageSize": "1K"
      }
    }
  }'

​
Parameters

ParameterTypeRequiredDescription
keystringYesAPI key (query parameter)
contents[].parts[].textstringYesText prompt or instruction
contents[].parts[].inline_data.mime_typestringNoReference image type: image/jpeg, image/png, image/webp
contents[].parts[].inline_data.datastringNoBase64-encoded reference image
generationConfig.responseModalitiesarrayYes["IMAGE"] or ["TEXT", "IMAGE"]
generationConfig.imageConfig.aspectRatiostringNo1:1 / 4:3 / 3:4 / 16:9 / 9:16
generationConfig.imageConfig.imageSizestringNo512 / 1K / 2K / 4K (default: 1K)

API Reference

View the interactive API playground for Gemini 3.1 Flash Image.