Generate & edit images using Gemini (aka "Nano Banana")


You can ask a Gemini Image model to generate and edit images using both text-only and text-and-file prompts. When you use Firebase AI Logic, you can make this request directly from your app.

With this capability, you can do things like:

  • Iteratively generate images through conversation with natural language, adjusting images while maintaining consistency and context.

  • Generate images with high-quality text rendering, including long strings of text.

  • Generate interleaved text-image output. For example, a blog post with text and images in a single turn. Previously, this required stringing together multiple models.

  • Generate images using Gemini's world knowledge and reasoning capabilities.

You can configure the response modality for your request so that the model generates only images or both images and text. Find a complete list of supported features (along with example prompts) later on this page.

Jump to code for text-to-image Jump to code for interleaved text & images

Jump to code for image editing Jump to code for iterative image editing


See other guides for additional options for working with images
Analyze images Analyze images on-device Generate structured output

Before you begin

Click your Gemini API provider to view provider-specific content and code on this page.

If you haven't already, complete the getting started guide, which describes how to set up your Firebase project, connect your app to Firebase, add the SDK, initialize the backend service for your chosen Gemini API provider, and create a GenerativeModel instance.

For testing and iterating on your prompts, we recommend using Google AI Studio.

Models that support this capability

  • gemini-3-pro-image (aka "Nano Banana Pro")
  • gemini-3.1-flash-image (aka "Nano Banana 2")
  • gemini-3.1-flash-lite-image (aka "Nano Banana 2 Lite")

Image-generating Gemini 2.5 models support this capability, but they're all deprecated.

Generate and edit images

You can generate and edit images using a Gemini model.

Generate images (text-only input)

Before trying this sample, complete the Before you begin section of this guide to set up your project and app.
In that section, you'll also click a button for your chosen Gemini API provider so that you see provider-specific content on this page.

You can ask a Gemini Image model to generate images by prompting with text.

Create a GenerativeModel instance, include the response modality of IMAGE in your model configuration, and call generateContent.

Swift 


import FirebaseAILogic

// Initialize the Gemini Developer API backend service.
// Create a `GenerativeModel` instance with a Gemini model that supports image output.
let generativeModel = FirebaseAI.firebaseAI(backend: .googleAI()).generativeModel(
  modelName: "gemini-3.1-flash-image",
  // Configure the model to respond with images only.
  generationConfig: GenerationConfig(responseModalities: [.image])
)

// Provide a text prompt instructing the model to generate an image
let prompt = "Generate an image of the Eiffel tower with fireworks in the background."

// To generate an image, call `generateContent` with the text input
let response = try await model.generateContent(prompt)

// Handle the generated image
guard let inlineDataPart = response.inlineDataParts.first else {
  fatalError("No image data in response.")
}
guard let uiImage = UIImage(data: inlineDataPart.data) else {
  fatalError("Failed to convert data to UIImage.")
}

Kotlin 


// Initialize the Gemini Developer API backend service.
// Create a `GenerativeModel` instance with a Gemini model that supports image output.
val model = Firebase.ai(backend = GenerativeBackend.googleAI()).generativeModel(
    modelName = "gemini-3.1-flash-image",
    // Configure the model to respond with images only.
    generationConfig = generationConfig {
responseModalities = listOf(ResponseModality.IMAGE) }
)

// Provide a text prompt instructing the model to generate an image
val prompt = "Generate an image of the Eiffel tower with fireworks in the background."

// To generate image output, call `generateContent` with the text input
val generatedImageAsBitmap = model.generateContent(prompt)
    // Handle the generated image
    .candidates.first().content.parts.filterIsInstance<ImagePart>().firstOrNull()?.image

Java 


// Initialize the Gemini Developer API backend service.
// Create a `GenerativeModel` instance with a Gemini model that supports image output.
GenerativeModel ai = FirebaseAI.getInstance(GenerativeBackend.googleAI()).generativeModel(
    "gemini-3.1-flash-image",
    // Configure the model to respond with images only.
    new GenerationConfig.Builder()
        .setResponseModalities(Arrays.asList(ResponseModality.IMAGE))
        .build()
);

GenerativeModelFutures model = GenerativeModelFutures.from(ai);

// Provide a text prompt instructing the model to generate an image
Content prompt = new Content.Builder()
        .addText("Generate an image of the Eiffel Tower with fireworks in the background.")
        .build();

// To generate an image, call `generateContent` with the text input
ListenableFuture<GenerateContentResponse> response = model.generateContent(prompt);
Futures.addCallback(response, new FutureCallback<GenerateContentResponse>() {
    @Override
    public void onSuccess(GenerateContentResponse result) { 
        // iterate over all the parts in the first candidate in the result object
        for (Part part : result.getCandidates().get(0).getContent().getParts()) {
            if (part instanceof ImagePart) {
                ImagePart imagePart = (ImagePart) part;
                // The returned image as a bitmap
                Bitmap generatedImageAsBitmap = imagePart.getImage();
                break;
            }
        }
    }

    @Override
    public void onFailure(Throwable t) {
        t.printStackTrace();
    }
}, executor);

Web 


import { initializeApp } from "firebase/app";
import { getAI, getGenerativeModel, GoogleAIBackend, ResponseModality } from "firebase/ai";

// TODO(developer): Replace the following with your app's Firebase configuration
// See: https://firebase.google.com/docs/web/learn-more#config-object
const firebaseConfig = {
  // ...
};

// Initialize FirebaseApp
const firebaseApp = initializeApp(firebaseConfig);

// Initialize the Gemini Developer API backend service.
const ai = getAI(firebaseApp, { backend: new GoogleAIBackend() });

// Create a `GenerativeModel` instance with a model that supports your use case
const model = getGenerativeModel(ai, {
  model: "gemini-3.1-flash-image",
  // Configure the model to respond with images only.
  generationConfig: {
    responseModalities: [ResponseModality.IMAGE],
  },
});

// Provide a text prompt instructing the model to generate an image
const prompt = 'Generate an image of the Eiffel Tower with fireworks in the background.';

// To generate an image, call `generateContent` with the text input
const result = model.generateContent(prompt);

// Handle the generated image
try {
  const inlineDataParts = result.response.inlineDataParts();
  if (inlineDataParts?.[0]) {
    const image = inlineDataParts[0].inlineData;
    console.log(image.mimeType, image.data);
  }
} catch (err) {
  console.error('Prompt or candidate was blocked:', err);
}

Dart 


import 'package:firebase_ai/firebase_ai.dart';
import 'package:firebase_core/firebase_core.dart';
import 'firebase_options.dart';

await Firebase.initializeApp(
  options: DefaultFirebaseOptions.currentPlatform,
);

// Initialize the Gemini Developer API backend service.
// Create a `GenerativeModel` instance with a Gemini model that supports image output.
final model = FirebaseAI.googleAI().generativeModel(
  model: 'gemini-3.1-flash-image',
  // Configure the model to respond with images only.
  generationConfig: GenerationConfig(responseModalities: [ResponseModalities.image]),
);

// Provide a text prompt instructing the model to generate an image
final prompt = [Content.text('Generate an image of the Eiffel Tower with fireworks in the background.')];

// To generate an image, call `generateContent` with the text input
final response = await model.generateContent(prompt);
if (response.inlineDataParts.isNotEmpty) {
  final imageBytes = response.inlineDataParts[0].bytes;
  // Process the image
} else {
  // Handle the case where no images were generated
  print('Error: No images were generated.');
}

Unity 


using Firebase;
using Firebase.AI;

// Initialize the Gemini Developer API backend service.
// Create a `GenerativeModel` instance with a Gemini model that supports image output.
var model = FirebaseAI.GetInstance(FirebaseAI.Backend.GoogleAI()).GetGenerativeModel(
  modelName: "gemini-3.1-flash-image",
  // Configure the model to respond with images only.
  generationConfig: new GenerationConfig(
    responseModalities: new[] { ResponseModality.Image })
);

// Provide a text prompt instructing the model to generate an image
var prompt = "Generate an image of the Eiffel Tower with fireworks in the background.";

// To generate an image, call `GenerateContentAsync` with the text input
var response = await model.GenerateContentAsync(prompt);

var text = response