从 Imagen 迁移到 Gemini 图片模型（“Nano Banana”）


所有 Imagen 模型均已废弃，并将于 2026 年 6 月 24 日 停止服务 。此废弃和停止服务适用于 Google 的所有产品，并且适用于 Gemini Developer API 和 Vertex AI Gemini API。

在此停止服务日期之前，为避免服务中断，您应按照本指南中的说明，将 应用从使用 Imagen 模型迁移到使用 Gemini 图片模型 （“Nano Banana”模型）。

如果您有与此废弃和停止服务相关的紧急问题， 请与 Firebase 支持团队联系。

替代 Gemini 图片模型

请查看下表，为您的应用选择替代 Gemini 图片模型 。

Imagen 模型 Gemini 图片模型（"Nano Banana"）
imagen-4.0-fast-generate-001 gemini-2.5-flash-image（正式版）
gemini-3.1-flash-image-preview（思考等级为 MINIMAL）
imagen-4.0-generate-001 gemini-2.5-flash-image（正式版）
gemini-3.1-flash-image-preview（思考等级为 HIGH）
imagen-4.0-ultra-generate-001 gemini-2.5-flash-image （正式版）
gemini-3-pro-image-preview
imagen-3.0-capability-001 gemini-2.5-flash-image （正式版）
gemini-3.1-flash-image-preview

迁移您的应用

本部分展示了从 Imagen模型迁移到Gemini图片模型的前后示例。

根据文字生成图片

点击您的 Gemini API 提供商，以查看此页面上特定于提供商的内容 和代码。

如需根据文字生成图片，请迁移您的应用：

Swift

之前


import FirebaseAILogic

// Initialize the Gemini Developer API backend service
let ai = FirebaseAI.firebaseAI(backend: .googleAI())

// Create an `ImagenModel` instance with a model that supports your use case
let model = ai.imagenModel(modelName: "IMAGEN_MODEL_NAME")

// Provide an image generation prompt
let prompt = "An astronaut riding a horse"

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

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

之后


import FirebaseAILogic

// Initialize the Gemini Developer API backend service
let ai = FirebaseAI.firebaseAI(backend: .googleAI())

// Create a `GenerativeModel` instance with a Gemini model that supports image output
let model = ai.generativeModel(
  modelName: "GEMINI_IMAGE_MODEL_NAME",
  generationConfig: GenerationConfig(
    responseModalities: [.image],
    imageConfig: ImageConfig(aspectRatio: .landscape4x3)
  )
)

// Provide an image generation prompt
let prompt = "An astronaut riding a horse"

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

// Handle the case where no images were generated
guard let inlineDataPart = response.inlineDataParts.first else {
  fatalError("No image in the response.")
}

// Process the image
guard let uiImage = UIImage(data: inlineDataPart.data) else {
  fatalError("Failed to convert data to UIImage.")
}

Kotlin

之前


// Initialize the Gemini Developer API backend service
val ai = Firebase.ai(backend = GenerativeBackend.googleAI())

// Create an `ImagenModel` instance with an Imagen model that supports your use case
val model = ai.imagenModel("IMAGEN_MODEL_NAME")

// Provide an image generation prompt
val prompt = "An astronaut riding a horse"

// To generate an image, call `generateImages` with the text prompt
val imageResponse = model.generateImages(prompt)

// Handle the generated image
val image = imageResponse.images.first()

val bitmapImage = image.asBitmap()

之后


// Initialize the Gemini Developer API backend service
val ai = Firebase.ai(backend = GenerativeBackend.googleAI())

// Create a `GenerativeModel` instance with a Gemini model that supports image output
val model = ai.generativeModel(
    modelName = "GEMINI_IMAGE_MODEL_NAME",
    generationConfig = generationConfig {
      responseModalities = listOf(ResponseModality.IMAGE),
      imageConfig = imageConfig {
        aspectRatio = AspectRatio.LANDSCAPE_4x3
      }
    }
)

// Provide an image generation prompt
val prompt = "An astronaut riding a horse"

// To generate an image, call `generateContent` with the text prompt
val imageResponse = model.generateContent(prompt)

if (imageResponse.finishReason == FinishReason.NO_IMAGE) {
  // Handle the case where no images were generated
} else {
  // Handle the generated image
  val bitmapImage = imageResponse.candidates.first().content.parts.filterIsInstance().firstOrNull()?.image
}

Java

之前


// Initialize the Gemini Developer API backend service
// Create an `ImagenModel` instance with an Imagen model that supports your use case
ImagenModel imagenModel = FirebaseAI.getInstance(GenerativeBackend.googleAI())
        .imagenModel(
                /* modelName */ "IMAGEN_MODEL_NAME");

ImagenModelFutures model = ImagenModelFutures.from(imagenModel);

// Provide an image generation prompt
String prompt = "An astronaut riding a horse";

// To generate an image, call `generateImages` with the text prompt
Futures.addCallback(model.generateImages(prompt), new FutureCallback<ImagenGenerationResponse>() {
    @Override
    public void onSuccess(ImagenGenerationResponse result) {
        if (result.getImages().isEmpty()) {
            Log.d("TAG", "No images generated");
        }
        Bitmap bitmap = result.getImages().get(0).asBitmap();
        // Use the bitmap to display the image in your UI
    }

    @Override
    public void onFailure(Throwable t) {
        // ...
    }
}, Executors.newSingleThreadExecutor());

之后


// 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_IMAGE_MODEL_NAME",
    new GenerationConfig.Builder()
        .setResponseModalities(Arrays.asList(ResponseModality.IMAGE))
        .setImageConfig(new ImageConfig(AspectRatio.LANDSCAPE_4x3, null))
        .build()
);

GenerativeModelFutures model = GenerativeModelFutures.from(ai);

// Provide a text prompt instructing the model to generate an image
Content prompt = new Content.Builder()
        .addText("An astronaut riding a horse")
        .build();

// To generate an image, call `generateContent` with the text input
Executor executor = Executors.newSingleThreadExecutor();
ListenableFuture response = model.generateContent(prompt);
Futures.addCallback(response, new FutureCallback() {
    @Override
    public void onSuccess(GenerateContentResponse result) {
        if (result.finishReason == FinishReason.NO_IMAGE) {
            // handle the case where no images were generated
            return;
        }
        // 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

之前


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

// TODO(developer) Replace the following with your app's Firebase configuration
const firebaseConfig = {
  // ...
};

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

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

// Create an `ImagenModel` instance with an Imagen model that supports your use case
const model = getImagenModel(ai, { model: "IMAGEN_MODEL_NAME" });

// Provide an image generation prompt
const prompt = "An astronaut riding a horse.";

// To generate an image, call `generateImages` with the text prompt
const response = await model.generateImages(prompt)

// If fewer images were generated than were requested,
// then `filteredReason` will describe the reason they were filtered out
if (response.filteredReason) {
  console.log(response.filteredReason);
}

if (response.images.length == 0) {
  throw new Error("No images in the response.")
}

const image = response.images[0];

之后


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

// TODO(developer) Replace the following with your app's Firebase configuration
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_IMAGE_MODEL_NAME",
  generationConfig: {
    responseModalities: [ResponseModality.IMAGE],
    imageConfig: {
      aspectRatio: ImageConfigAspectRatio.LANDSCAPE_4x3
    }
  },
});

// Provide an image generation prompt
const prompt = "An astronaut riding a horse.";

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

// Handle the generated image
try {
  const response = result.response;
  if (response.candidates?.[0].finishReason == FinishReason.NO_IMAGE) {
    // Handle the case where no images were generated
  }
  const inlineDataParts = response.inlineDataParts();
  if (inlineDataParts?.[0]) {
    const image = inlineDataParts[0].inlineData;
    // Use this mimeType and base64 data to display the image using
    // your preferred tooling
    console.log(image.mimeType, image.data);
  }
} catch (err) {
  console.error('Prompt or candidate was blocked:', err);
}

Dart

之前


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

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

// Initialize the Gemini Developer API backend service
final ai = FirebaseAI.googleAI();

// Create an `ImagenModel` instance with an Imagen model that supports your use case
final model = ai.imagenModel(model: 'IMAGEN_MODEL_NAME');

// Provide an image generation prompt
const prompt = 'An astronaut riding a horse.';

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

if (response.images.isNotEmpty) {
  final image = response.images[0];
  // Process the image
} else {
  // Handle the case where no images were generated
  print('Error: No images were generated.');
}

之后


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

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

// Initialize the Gemini Developer API backend service
final ai = FirebaseAI.googleAI();

// Create a `GenerativeModel` instance with a Gemini model that supports image output
final model = ai.generativeModel(
  model: 'GEMINI_IMAGE_MODEL_NAME',
  generationConfig: GenerationConfig(
    responseModalities: [ResponseModalities.image],
    imageConfig: ImageConfig(aspectRatio: ImageAspectRatio.landscape4x3)
  ),
);

// Provide a text prompt instructing the model to generate an image
final prompt = [Content.text('An astronaut riding a horse.')];

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

Unity

之前


using Firebase.AI;

// Initialize the Gemini Developer API backend service
var ai = FirebaseAI.GetInstance(FirebaseAI.Backend.GoogleAI());

// Create an `ImagenModel` instance with a model that supports your use case
var model = ai.GetImagenModel(modelName: "IMAGEN_MODEL_NAME");

// Provide an image generation prompt
var prompt = "An astronaut riding a horse";

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

// Handle the generated image
if (response.Images.Count == 0) {
  throw new Exception("No image in the response.");
}
var image = response.Images[0].AsTexture2D();

之后


using Firebase;
using Firebase.AI;

// Initialize the Gemini Developer API backend service
var ai = FirebaseAI.GetInstance(FirebaseAI.Backend.GoogleAI());

// Create a `GenerativeModel` instance with a Gemini model that supports image output
var model = ai.GetGenerativeModel(
  modelName: "GEMINI_IMAGE_MODEL_NAME",
  generationConfig: new GenerationConfig(
    responseModalities: new[] { ResponseModality.Image },
    imageConfig: new ImageConfig(aspectRatio: ImageConfig.AspectRatio.Landscape4x3)
  )
);

// Provide an image generation prompt
var prompt = "An astronaut riding a horse";

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

if (response.Candidates.First().FinishReason == FinishReason.NoImage) {
  // Handle the case where no images were generated
}

// Handle the generated image
var imageParts = response.Candidates.First().Content.Parts
                         .OfType<ModelContent.InlineDataPart>()
                         .Where(part => part.MimeType == "image/png");

foreach (var imagePart in imageParts) {
  // Load the Image into a Unity Texture2D object
  UnityEngine.Texture2D texture2D = new(2, 2);
  if (texture2D.LoadImage(imagePart.Data.ToArray())) {
    // Do something with the image
  }
}

替代配置选项

本部分介绍了各种模型配置选项的替代选项，以帮助控制模型的响应。

安全设置

您可以使用 ImagenSafetySettings 配置 Imagen 模型的安全设置。不过，对于 Gemini 图片模型，您需要 迁移到使用 SafetySetting。

模型配置参数

您可以使用 ImagenGenerationConfig 配置 Imagen 模型。不过， 对于 Gemini 图片模型，您需要迁移到使用 GenerationConfig，并且可以选择使用嵌套的 ImageConfig （此配置从 2026 年 5 月初的 SDK 版本开始提供）。

在 GenerationConfig 中，将响应模态设置为 IMAGE（如本指南前面“之后”代码示例所示）。请注意，您可以选择 配置 Gemini 图片模型以同时返回 IMAGE 和 TEXT。

请查看下表，了解如何将模型 配置参数从 Imagen 迁移到 Gemini 图片模型：

Imagen 模型 Gemini 图片模型（"Nano Banana"）
addWatermark

不支持

Gemini 图片模型始终返回带有 SynthID 水印的生成图片。

aspectRatio

在 ImageConfig 中使用 aspectRatio

如需查看代码示例和支持的值，请参阅 配置图片生成 在 Gemini 图片模型指南中。

imageFormat

不支持

Gemini 图片模型始终以 PNG 格式返回生成的图片。

negativePrompt

不支持

请注意，否定提示是一项旧版功能，自 imagen-3.0-generate-002（或任何 Imagen 4 模型）以来，该功能已不受支持。
numberOfImages

不支持

Gemini 图片模型始终返回一张生成的图片。
作为一种变通方法，您可以在循环中运行生成，以实现相同的结果。 请注意，候选计数不能作为替代方案。

personGeneration

不支持

默认情况下，Gemini 图片模型允许生成人物图片。