Gemini 3.1 Flash Image Preview (Nano Banana 2) Now Available

Date: 2026-02-27 / (1404-12-08)

Summary

We announce the addition of Google's Gemini 3.1 Flash Image Preview (gemini-3.1-flash-image-preview), also known as "Nano Banana 2". This model brings high-fidelity image generation and faster, advanced editing to the Flash model series, serving as the high-efficiency counterpart to Gemini 3 Pro Image with an exceptional price-performance ratio optimized for high-volume developer use cases.

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Details

Google Gemini 3.1 Flash Image Preview (Nano Banana 2)

Google's gemini-3.1-flash-image-preview (also known as "Nano Banana 2") is now available through AvalAI. This model delivers high-fidelity image generation and advanced editing capabilities, optimized for speed and high-volume developer workflows.

Model Name: gemini-3.1-flash-image-preview
Alias: Nano Banana 2

Key Features

• Improved World Knowledge: Leverages Gemini's broad world knowledge with web search grounding to create enhanced visuals using real-world references
• Advanced Text Rendering: Delivers reliable, crisp text rendering with in-image localization supporting multiple languages
• Greater Creative Control: Vibrant lighting, richer textures, sharper details with configurable thinking levels
• Native Aspect Ratios: Support for all existing aspect ratios plus new 4:1, 1:4, 8:1, and 1:8 ratios
• New 512px Resolution: Optimized for efficiency with minimal latency for rapid iterations
• Improved Instruction Following: Adheres more strictly to complex, multi-layered prompts
• Resolution Support: Generate images up to 4K resolution (4096x4096px)
• Image Editing: Comprehensive editing capabilities including multi-turn conversational editing
• Google Image Search Grounding: Generate images based on real-world image references (exclusive to 3.1 Flash)

Pricing

Type	Cost
Input Text	$0.50 per 1M tokens
Input Image	$0.50 per 1M tokens
Cached Input	$0.25 per 1M tokens
Output Text	$3.00 per 1M tokens
Output Image (1K-2K)	$0.0672 per image
Output Image (2K-4K)	$0.101 per image
Output Image (4K)	$0.151 per image

Note: Image output is priced at $60 per 1M tokens. Output images from 1024x1024px (1K) to 2048x2048px (2K) consume approximately 1120 tokens.

Understanding the Nano Banana Family

Nano Banana is the name for Gemini's native image generation capabilities. Gemini can generate and process images conversationally with text, images, or a combination of both:

• Nano Banana 2 (gemini-3.1-flash-image-preview): The high-efficiency counterpart to Gemini 3 Pro Image, optimized for speed and high-volume developer use cases
• Nano Banana Pro (gemini-3-pro-image-preview): Designed for professional asset production with advanced reasoning ("Thinking") for complex instructions and high-fidelity text
• Nano Banana (gemini-2.5-flash-image): Designed for speed and efficiency, optimized for high-volume, low-latency tasks

API Request/Response Examples

Using Chat Completions Endpoint:

curl https://api.avalai.ir/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $AVALAI_API_KEY" \
  -d '{
    "model": "gemini-3.1-flash-image-preview",
    "messages": [
      {
        "role": "user",
        "content": "Create a photorealistic portrait of a nano banana dish in a fancy restaurant with a Gemini theme"
      }
    ],
    "modalities": ["image", "text"]
  }' | jq '.choices[0].message.images[0].image_url.url |= (.[0:100] + "...[TRUNCATED]")'

Response:

{
  "id": "chatcmpl-xyz123",
  "created": 1740642000,
  "model": "gemini-3.1-flash-image-preview",
  "object": "chat.completion",
  "system_fingerprint": null,
  "choices": [
    {
      "finish_reason": "stop",
      "index": 0,
      "message": {
        "content": "I've created a photorealistic image of a nano banana dish in an elegant restaurant setting with a Gemini constellation theme.",
        "role": "assistant",
        "images": [
          {
            "image_url": {
              "url": "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAABAAAAAQACAIAAADwf7zU...[TRUNCATED]",
              "detail": "auto"
            },
            "index": 0,
            "type": "image_url"
          }
        ],
        "thinking_blocks": [],
        "annotations": []
      }
    }
  ],
  "usage": {
    "completion_tokens": 1150,
    "prompt_tokens": 28,
    "total_tokens": 1178,
    "completion_tokens_details": null,
    "prompt_tokens_details": {
      "audio_tokens": null,
      "cached_tokens": null,
      "text_tokens": 28,
      "image_tokens": null
    }
  },
  "estimated_cost": {
    "unit": "0.0695000000",
    "irt": 7968.3,
    "exchange_rate": 114600
  }
}

SDK Usage Examples

Bash

curl https://api.avalai.ir/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $AVALAI_API_KEY" \
  -d '{
    "model": "gemini-3.1-flash-image-preview",
    "messages": [
      {
        "role": "user",
        "content": "Create a modern logo for a tech company called \"AvalAI\" with clean typography and a minimalist design"
      }
    ],
    "modalities": ["image", "text"]
  }'

Python

from openai import OpenAI

client = OpenAI(api_key="your-avalai-api-key", base_url="https://api.avalai.ir/v1")

response = client.chat.completions.create(
    model="gemini-3.1-flash-image-preview",
    messages=[
        {
            "role": "user",
            "content": 'Create a modern logo for a tech company called "AvalAI" with clean typography and a minimalist design',
        }
    ],
    extra_body={"modalities": ["image", "text"]},
)

# Access the generated image
if hasattr(response.choices[0].message, "images"):
    images = getattr(response.choices[0].message, "images")
    for img in images:
        print(f"Image URL: {img.image_url.url[:100]}...")

print(response.choices[0].message.content)

JavaScript

import { OpenAI } from "openai";

const client = new OpenAI({
  apiKey: process.env.AVALAI_API_KEY,
  baseURL: "https://api.avalai.ir/v1",
});

const response = await client.chat.completions.create({
  model: "gemini-3.1-flash-image-preview",
  messages: [
    {
      role: "user",
      content: "Create a modern logo for a tech company called \"AvalAI\" with clean typography and a minimalist design",
    },
  ],
  modalities: ["image", "text"],
});

// Access the generated image
if (response.choices[0].message.images) {
  const images = response.choices[0].message.images;
  images.forEach((img, idx) => {
    console.log(`Image ${idx}: ${img.image_url.url.substring(0, 100)}...`);
  });
}

console.log(response.choices[0].message.content);

Image Editing Example

Bash

curl https://api.avalai.ir/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $AVALAI_API_KEY" \
  -d '{
    "model": "gemini-3.1-flash-image-preview",
    "messages": [
      {
        "role": "user",
        "content": [
          {
            "type": "text",
            "text": "Transform this image into a cyberpunk style with neon colors"
          },
          {
            "type": "image_url",
            "image_url": {
              "url": "https://example.com/original-image.jpg"
            }
          }
        ]
      }
    ],
    "modalities": ["image", "text"]
  }'

Python

from openai import OpenAI

client = OpenAI(api_key="your-avalai-api-key", base_url="https://api.avalai.ir/v1")

response = client.chat.completions.create(
    model="gemini-3.1-flash-image-preview",
    messages=[
        {
            "role": "user",
            "content": [
                {
                    "type": "text",
                    "text": "Transform this image into a cyberpunk style with neon colors",
                },
                {
                    "type": "image_url",
                    "image_url": {"url": "https://example.com/original-image.jpg"},
                },
            ],
        }
    ],
    extra_body={"modalities": ["image", "text"]},
)

JavaScript

import { OpenAI } from "openai";

const client = new OpenAI({
  apiKey: process.env.AVALAI_API_KEY,
  baseURL: "https://api.avalai.ir/v1",
});

const response = await client.chat.completions.create({
  model: "gemini-3.1-flash-image-preview",
  messages: [
    {
      role: "user",
      content: [
        {
          type: "text",
          text: "Transform this image into a cyberpunk style with neon colors",
        },
        {
          type: "image_url",
          image_url: { url: "https://example.com/original-image.jpg" },
        },
      ],
    },
  ],
  modalities: ["image", "text"],
});

Native Gemini SDK Example

You can also use the native Gemini API (v1beta) to access this model with Google's official SDK:

from google import genai
from google.genai import types
from PIL import Image

client = genai.Client(
    api_key="your-avalai-api-key",
    http_options=types.HttpOptions(base_url="https://api.avalai.ir/v1beta"),
)

prompt = (
    "Create a picture of a nano banana dish in a fancy restaurant with a Gemini theme"
)
response = client.models.generate_content(
    model="gemini-3.1-flash-image-preview",
    contents=[prompt],
)

for part in response.parts:
    if part.text is not None:
        print(part.text)
    elif part.inline_data is not None:
        image = part.as_image()
        image.save("generated_image.png")

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Related Links

• Google Models Documentation
• Nano Banana Series Guide
• Native Gemini API Reference
• Image Generation Guide
• Pricing Information