# 画像を生成する
<a name="code-examples-image"></a>

以下のコード例では、Amazon Bedrock で Amazon Nova Canvas を呼び出して画像を生成する方法が示されています。

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#### [ .NET ]

**SDK for .NET**  
 GitHub には、その他のリソースもあります。[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/dotnetv3/Bedrock-runtime#code-examples)で完全な例を見つけて、設定と実行の方法を確認してください。
Amazon Nova Canvas で画像を作成します。  

```
// Use the native inference API to create an image with Amazon Nova Canvas.

using System;
using System.IO;
using System.Text.Json;
using System.Text.Json.Nodes;
using Amazon;
using Amazon.BedrockRuntime;
using Amazon.BedrockRuntime.Model;

// Create a Bedrock Runtime client in the AWS Region you want to use.
var client = new AmazonBedrockRuntimeClient(RegionEndpoint.USEast1);

// Set the model ID.
var modelId = "amazon.nova-canvas-v1:0";

// Define the image generation prompt for the model.
var prompt = "A stylized picture of a cute old steampunk robot.";

// Create a random seed between 0 and 858,993,459
int seed = new Random().Next(0, 858993460);

//Format the request payload using the model's native structure.
var nativeRequest = JsonSerializer.Serialize(new
{
    taskType = "TEXT_IMAGE",
    textToImageParams = new
    {
        text = prompt
    },
    imageGenerationConfig = new
    {
        seed,
        quality = "standard",
        width = 512,
        height = 512,
        numberOfImages = 1
    }
});

// Create a request with the model ID and the model's native request payload.
var request = new InvokeModelRequest()
{
    ModelId = modelId,
    Body = new MemoryStream(System.Text.Encoding.UTF8.GetBytes(nativeRequest)),
    ContentType = "application/json"
};

try
{
    // Send the request to the Bedrock Runtime and wait for the response.
    var response = await client.InvokeModelAsync(request);

    // Decode the response body.
    var modelResponse = await JsonNode.ParseAsync(response.Body);

    // Extract the image data.
    var base64Image = modelResponse["images"]?[0].ToString() ?? "";

    // Save the image in a local folder
    string savedPath = AmazonNovaCanvas.InvokeModel.SaveBase64Image(base64Image);
    Console.WriteLine($"Image saved to: {savedPath}");
}
catch (AmazonBedrockRuntimeException e)
{
    Console.WriteLine($"ERROR: Can't invoke '{modelId}'. Reason: {e.Message}");
    throw;
}
```
+  API の詳細については、「**AWS SDK for .NET API リファレンス」の「[InvokeModel](https://docs.aws.amazon.com/goto/DotNetSDKV3/bedrock-runtime-2023-09-30/InvokeModel)」を参照してください。

------
#### [ Java ]

**SDK for Java 2.x**  
 GitHub には、その他のリソースもあります。[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javav2/example_code/bedrock-runtime#code-examples)で完全な例を見つけて、設定と実行の方法を確認してください。
Amazon Nova Canvas で画像を作成します。  

```
import org.json.JSONObject;
import org.json.JSONPointer;
import software.amazon.awssdk.auth.credentials.DefaultCredentialsProvider;
import software.amazon.awssdk.core.SdkBytes;
import software.amazon.awssdk.core.exception.SdkClientException;
import software.amazon.awssdk.regions.Region;
import software.amazon.awssdk.services.bedrockruntime.BedrockRuntimeClient;
import software.amazon.awssdk.services.bedrockruntime.model.InvokeModelResponse;

import java.security.SecureRandom;
import java.util.Base64;

import static com.example.bedrockruntime.libs.ImageTools.displayImage;

/**
 * This example demonstrates how to use Amazon Nova Canvas to generate images.
 * It shows how to:
 * - Set up the Amazon Bedrock runtime client
 * - Configure the image generation parameters
 * - Send a request to generate an image
 * - Process the response and handle the generated image
 */
public class InvokeModel {

    public static byte[] invokeModel() {

        // Step 1: Create the Amazon Bedrock runtime client
        // The runtime client handles the communication with AI models on Amazon Bedrock
        BedrockRuntimeClient client = BedrockRuntimeClient.builder()
                .credentialsProvider(DefaultCredentialsProvider.create())
                .region(Region.US_EAST_1)
                .build();

        // Step 2: Specify which model to use
        // For the latest available models, see:
        // https://docs.aws.amazon.com/bedrock/latest/userguide/models-supported.html
        String modelId = "amazon.nova-canvas-v1:0";

        // Step 3: Configure the generation parameters and create the request
        // First, set the main parameters:
        // - prompt: Text description of the image to generate
        // - seed: Random number for reproducible generation (0 to 858,993,459)
        String prompt = "A stylized picture of a cute old steampunk robot";
        int seed = new SecureRandom().nextInt(858_993_460);

        // Then, create the request using a template with the following structure:
        // - taskType: TEXT_IMAGE (specifies text-to-image generation)
        // - textToImageParams: Contains the text prompt
        // - imageGenerationConfig: Contains optional generation settings (seed, quality, etc.)
        // For a list of available request parameters, see:
        // https://docs.aws.amazon.com/nova/latest/userguide/image-gen-req-resp-structure.html
        String request = """
                {
                    "taskType": "TEXT_IMAGE",
                    "textToImageParams": {
                        "text": "{{prompt}}"
                    },
                    "imageGenerationConfig": {
                        "seed": {{seed}},
                        "quality": "standard"
                    }
                }"""
                .replace("{{prompt}}", prompt)
                .replace("{{seed}}", String.valueOf(seed));

        // Step 4: Send and process the request
        // - Send the request to the model using InvokeModelResponse
        // - Extract the Base64-encoded image from the JSON response
        // - Convert the encoded image to a byte array and return it
        try {
            InvokeModelResponse response = client.invokeModel(builder -> builder
                    .modelId(modelId)
                    .body(SdkBytes.fromUtf8String(request))
            );

            JSONObject responseBody = new JSONObject(response.body().asUtf8String());
            // Convert the Base64 string to byte array for better handling
            return Base64.getDecoder().decode(
                    new JSONPointer("/images/0").queryFrom(responseBody).toString()
            );

        } catch (SdkClientException e) {
            System.err.printf("ERROR: Can't invoke '%s'. Reason: %s%n", modelId, e.getMessage());
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) {
        System.out.println("Generating image. This may take a few seconds...");
        byte[] imageData = invokeModel();
        displayImage(imageData);
    }
}
```
+  API の詳細については、「**AWS SDK for Java 2.x API リファレンス」の「[InvokeModel](https://docs.aws.amazon.com/goto/SdkForJavaV2/bedrock-runtime-2023-09-30/InvokeModel)」を参照してください。

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#### [ JavaScript ]

**SDK for JavaScript (v3)**  
 GitHub には、その他のリソースもあります。[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/javascriptv3/example_code/bedrock-runtime#code-examples)で完全な例を見つけて、設定と実行の方法を確認してください。
Amazon Nova Canvas で画像を作成します。  

```
import {
  BedrockRuntimeClient,
  InvokeModelCommand,
} from "@aws-sdk/client-bedrock-runtime";
import { saveImage } from "../../utils/image-creation.js";
import { fileURLToPath } from "node:url";

/**
 * This example demonstrates how to use Amazon Nova Canvas to generate images.
 * It shows how to:
 * - Set up the Amazon Bedrock runtime client
 * - Configure the image generation parameters
 * - Send a request to generate an image
 * - Process the response and handle the generated image
 *
 * @returns {Promise<string>} Base64-encoded image data
 */
export const invokeModel = async () => {
  // Step 1: Create the Amazon Bedrock runtime client
  // Credentials will be automatically loaded from the environment
  const client = new BedrockRuntimeClient({ region: "us-east-1" });

  // Step 2: Specify which model to use
  // For the latest available models, see:
  // https://docs.aws.amazon.com/bedrock/latest/userguide/models-supported.html
  const modelId = "amazon.nova-canvas-v1:0";

  // Step 3: Configure the request payload
  // First, set the main parameters:
  // - prompt: Text description of the image to generate
  // - seed: Random number for reproducible generation (0 to 858,993,459)
  const prompt = "A stylized picture of a cute old steampunk robot";
  const seed = Math.floor(Math.random() * 858993460);

  // Then, create the payload using the following structure:
  // - taskType: TEXT_IMAGE (specifies text-to-image generation)
  // - textToImageParams: Contains the text prompt
  // - imageGenerationConfig: Contains optional generation settings (seed, quality, etc.)
  // For a list of available request parameters, see:
  // https://docs.aws.amazon.com/nova/latest/userguide/image-gen-req-resp-structure.html
  const payload = {
    taskType: "TEXT_IMAGE",
    textToImageParams: {
      text: prompt,
    },
    imageGenerationConfig: {
      seed,
      quality: "standard",
    },
  };

  // Step 4: Send and process the request
  // - Embed the payload in a request object
  // - Send the request to the model
  // - Extract and return the generated image data from the response
  try {
    const request = {
      modelId,
      body: JSON.stringify(payload),
    };
    const response = await client.send(new InvokeModelCommand(request));

    const decodedResponseBody = new TextDecoder().decode(response.body);
    // The response includes an array of base64-encoded PNG images
    /** @type {{images: string[]}} */
    const responseBody = JSON.parse(decodedResponseBody);
    return responseBody.images[0]; // Base64-encoded image data
  } catch (error) {
    console.error(`ERROR: Can't invoke '${modelId}'. Reason: ${error.message}`);
    throw error;
  }
};

// If run directly, execute the example and save the generated image
if (process.argv[1] === fileURLToPath(import.meta.url)) {
  console.log("Generating image. This may take a few seconds...");
  invokeModel()
    .then(async (imageData) => {
      const imagePath = await saveImage(imageData, "nova-canvas");
      // Example path: javascriptv3/example_code/bedrock-runtime/output/nova-canvas/image-01.png
      console.log(`Image saved to: ${imagePath}`);
    })
    .catch((error) => {
      console.error("Execution failed:", error);
      process.exitCode = 1;
    });
}
```
+  API の詳細については、「**AWS SDK for JavaScript API リファレンス」の「[InvokeModel](https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/client/bedrock-runtime/command/InvokeModelCommand)」を参照してください。

------
#### [ Python ]

**SDK for Python (Boto3)**  
 GitHub には、その他のリソースもあります。[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/bedrock-runtime#code-examples)で完全な例を見つけて、設定と実行の方法を確認してください。
Amazon Nova Canvas で画像を作成します。  

```
# Use the native inference API to create an image with Amazon Nova Canvas

import base64
import json
import os
import random

import boto3

# Create a Bedrock Runtime client in the AWS Region of your choice.
client = boto3.client("bedrock-runtime", region_name="us-east-1")

# Set the model ID.
model_id = "amazon.nova-canvas-v1:0"

# Define the image generation prompt for the model.
prompt = "A stylized picture of a cute old steampunk robot."

# Generate a random seed between 0 and 858,993,459
seed = random.randint(0, 858993460)

# Format the request payload using the model's native structure.
native_request = {
    "taskType": "TEXT_IMAGE",
    "textToImageParams": {"text": prompt},
    "imageGenerationConfig": {
        "seed": seed,
        "quality": "standard",
        "height": 512,
        "width": 512,
        "numberOfImages": 1,
    },
}

# Convert the native request to JSON.
request = json.dumps(native_request)

# Invoke the model with the request.
response = client.invoke_model(modelId=model_id, body=request)

# Decode the response body.
model_response = json.loads(response["body"].read())

# Extract the image data.
base64_image_data = model_response["images"][0]

# Save the generated image to a local folder.
i, output_dir = 1, "output"
if not os.path.exists(output_dir):
    os.makedirs(output_dir)
while os.path.exists(os.path.join(output_dir, f"nova_canvas_{i}.png")):
    i += 1

image_data = base64.b64decode(base64_image_data)

image_path = os.path.join(output_dir, f"nova_canvas_{i}.png")
with open(image_path, "wb") as file:
    file.write(image_data)

print(f"The generated image has been saved to {image_path}")
```
+  API の詳細については、*AWS SDK for Python (Boto3) API リファレンス*の「[InvokeModel](https://docs.aws.amazon.com/goto/boto3/bedrock-runtime-2023-09-30/InvokeModel)」を参照してください。

------
#### [ Swift ]

**SDK for Swift**  
 GitHub には、その他のリソースもあります。[AWS コード例リポジトリ](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/swift/example_code/bedrock-runtime#code-examples)で完全な例を見つけて、設定と実行の方法を確認してください。
Amazon Nova Canvas で画像を作成します。  

```
// Use the native inference API to create an image with Amazon Nova Canvas

import AWSBedrockRuntime
import AWSSDKIdentity
import Foundation

struct NovaImageOutput: Decodable {
    let images: [Data]
}

func generateImage(_ textPrompt: String) async throws {
    // Create a Bedrock Runtime client in the AWS Region you want to use.
    let config =
        try await BedrockRuntimeClient.BedrockRuntimeClientConfiguration(
            region: "us-east-1"
        )
    config.awsCredentialIdentityResolver = try SSOAWSCredentialIdentityResolver()

    let client = BedrockRuntimeClient(config: config)

    // Set the model ID.
    let modelId = "amazon.nova-canvas-v1:0"

    //  Format the request payload using the model's native structure.
    let input = InvokeModelInput(
        accept: "application/json",
        body: """
            {
                "textToImageParams": {
                    "text": "\(textPrompt)"
                },
                "taskType": "TEXT_IMAGE",
                "imageGenerationConfig": {
                    "seed": 42,
                    "quality": "standard",
                    "width": 512,
                    "height": 512,
                    "numberOfImages": 1
                }
            }
            """.data(using: .utf8),
        modelId: modelId
    )

    // Invoke the model with the request.
    let response = try await client.invokeModel(input: input)

    // Decode the response body.
    let output = try JSONDecoder().decode(NovaImageOutput.self, from: response.body!)

    // Extract the image data.
    guard let data = output.images.first else {
        print("No image data found")
        return
    }

    // Save the generated image to a local folder.
    let fileURL = URL.documentsDirectory.appending(path: "nova_canvas.png")
    print(fileURL)
    try data.write(to: fileURL)
    print("Image is saved at \(fileURL)")
}
```
+  API の詳細については、「*AWS SDK for Swift API リファレンス*」の「[InvokeModel](https://sdk.amazonaws.com/swift/api/awsbedrockruntime/latest/documentation/awsbedrockruntime/bedrockruntimeclient/invokemodel(input:))」を参照してください。

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