Migrate image generation from DALL‑E to gpt-image-1-mini

README.md

@@ -40,7 +40,7 @@ Main utility function that creates a complete story with title and image.
 - `title`: Generated story title
 - `content`: The story content
 - `temperature`: Temperature value used for generation
-- `image`: URL to the generated image (Note: this link expires, so download it)
+- `image`: Image data URL for the generated image (base64 for GPT image models)
 
 **Example:**
 ```typescript
@@ -86,13 +86,13 @@ Generates a title for the story.
 
 #### `story.generateImage(size?, model?)`
 
-Generates an image for the story using DALL-E.
+Generates an image for the story using OpenAI's GPT image models.
 
 **Parameters:**
-- `size` (ImageSize, optional): Image size. Defaults to `"1024x1024"`. Options: `'256x256' | '512x512' | '1024x1024' | '1792x1024' | '1024x1792'`
-- `model` (Model, optional): DALL-E model. Defaults to `"dall-e-3"`. Options: `'dall-e-2' | 'dall-e-3'`
+- `size` (ImageSize, optional): Image size. Defaults to `"1024x1024"`. Options: `'1024x1024' | '1536x1024' | '1024x1536'`
+- `model` (Model, optional): GPT image model. Defaults to `"gpt-image-1-mini"`
 
-**Returns:** `Promise<string>` - URL to the generated image
+**Returns:** `Promise<string>` - PNG data URL to the generated image
 
 ### `verifyPrompt(prompt, openai, chatModel?)`
 
@@ -123,7 +123,7 @@ if (result.validStory) {
 
 ### `ImageGenerator` Class
 
-Class for generating images using OpenAI's DALL-E.
+Class for generating images using OpenAI's GPT image models.
 
 #### Constructor: `new ImageGenerator(openai, logger)`
 
@@ -137,10 +137,10 @@ Generates a single image from a text prompt.
 
 **Parameters:**
 - `prompt` (string): The text prompt describing the image
-- `size` (ImageSize, optional): Image size. Defaults to `"512x512"`
-- `model` (Model, optional): DALL-E model. Defaults to `"dall-e-3"`
+- `size` (ImageSize, optional): Image size. Defaults to `"1024x1024"`
+- `model` (Model, optional): GPT image model. Defaults to `"gpt-image-1-mini"`
 
-**Returns:** `Promise<string>` - URL to the generated image
+**Returns:** `Promise<string>` - PNG data URL to the generated image
 
 **Example:**
 ```typescript
@@ -149,7 +149,7 @@ import { OpenAI } from "openai";
 
 const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });
 const imageGen = new ImageGenerator(openai, console);
-const imageUrl = await imageGen.generateImage("A sunset over mountains", "1024x1024", "dall-e-3");
+const imageUrl = await imageGen.generateImage("A sunset over mountains", "1024x1024", "gpt-image-1-mini");
 ```
 
 #### `imageGenerator.generateImages(prompt, numberOfImages, size?, model?)`
@@ -159,10 +159,10 @@ Generates multiple images from a text prompt.
 **Parameters:**
 - `prompt` (string): The text prompt describing the images
 - `numberOfImages` (number): Number of images to generate (1-5)
-- `size` (ImageSize, optional): Image size. Defaults to `"512x512"`
-- `model` (Model, optional): DALL-E model. Defaults to `"dall-e-3"`
+- `size` (ImageSize, optional): Image size. Defaults to `"1024x1024"`
+- `model` (Model, optional): GPT image model. Defaults to `"gpt-image-1-mini"`
 
-**Returns:** `Promise<string[]>` - Array of URLs to the generated images
+**Returns:** `Promise<string[]>` - Array of PNG data URLs to the generated images
 
 ### `ChatAssistant` Class
 
@@ -202,7 +202,7 @@ console.log("Argentina size is:", followUp.answer.content);
 ## Important Notes
 
 - **Temperature with gpt-5-mini**: The `gpt-5-mini` model only supports the default temperature value (1). When using this model, the library automatically omits the temperature parameter to avoid API errors.
-- **Image URLs**: Generated image URLs are temporary and will expire. Make sure to download the images if you need to persist them.
+- **Image data URLs**: GPT image models return base64 data URLs. If you need a persistent file, decode and save the image data.
 - **API Key**: You need a valid OpenAI API key to use this library. Set it as an environment variable or pass it directly to the OpenAI client.
 
 ## Development

e2e-test.mjs

@@ -116,11 +116,14 @@ async function testImageGeneration() {
         const imageUrl = await imageGen.generateImage(
             "A simple illustration of a sunset over mountains",
             "1024x1024",
-            "dall-e-3"
+            "gpt-image-1-mini"
         );
-
-        if (!imageUrl || typeof imageUrl !== "string" || !imageUrl.startsWith("http")) {
-            throw new Error("Invalid image URL");
+
+        const isHttpUrl = imageUrl.startsWith("http");
+        const isDataUrl = imageUrl.startsWith("data:image/");
+
+        if (!imageUrl || typeof imageUrl !== "string" || (!isHttpUrl && !isDataUrl)) {
+            throw new Error("Invalid image URL or data URL");
         }
 
         console.log(`✅ ImageGenerator.generateImage passed`);

package.json

@@ -40,6 +40,6 @@
     "typescript-eslint": "^7.9.0"
   },
   "dependencies": {
-    "openai": "^6.6.0"
+    "openai": "^6.37.0"
   }
 }

src/image.ts

@@ -1,11 +1,12 @@
 import type { OpenAI } from "openai";
+import type { ImageModel } from "openai/resources/images";
 import type { ILogger } from "./types";
 
-export type ImageSize = '256x256' | '512x512' | '1024x1024' | '1792x1024' | '1024x1792'
-export type Model = 'dall-e-2' | 'dall-e-3';
+export type ImageSize = '1024x1024' | '1536x1024' | '1024x1536';
+export type Model = Extract<ImageModel, 'gpt-image-1' | 'gpt-image-1-mini' | 'gpt-image-1.5' | 'gpt-image-2' | 'gpt-image-2-2026-04-21' | 'chatgpt-image-latest'>;
 
 /**
- * Class used to generate images using OpenAI's DALL-E
+ * Class used to generate images using OpenAI's GPT image models
  */
 export class ImageGenerator {
     /**
@@ -19,11 +20,11 @@ export class ImageGenerator {
     /**
      * Generates a single image from a text prompt
      * @param prompt The text prompt describing the image to generate
-     * @param size Optional, the size of the image. Defaults to "512x512"
-     * @param model Optional, the DALL-E model to use. Defaults to "dall-e-3"
-     * @returns A Promise that resolves to the URL of the generated image
+     * @param size Optional, the size of the image. Defaults to "1024x1024"
+     * @param model Optional, the GPT image model to use. Defaults to "gpt-image-1-mini"
+     * @returns A Promise that resolves to the PNG data URL of the generated image
      */
-    public async generateImage(prompt: string, size: ImageSize = "512x512", model: Model = "dall-e-3"): Promise<string> {
+    public async generateImage(prompt: string, size: ImageSize = "1024x1024", model: Model = "gpt-image-1-mini"): Promise<string> {
         const image = await this.generateImages(prompt, 1, size, model);
         return image[0]!;
     }
@@ -32,19 +33,22 @@ export class ImageGenerator {
      * Generates multiple images from a text prompt
      * @param prompt The text prompt describing the images to generate
      * @param numberOfImages The number of images to generate (1-5)
-     * @param size Optional, the size of the images. Defaults to "512x512"
-     * @param model Optional, the DALL-E model to use. Defaults to "dall-e-3"
-     * @returns A Promise that resolves to an array of URLs for the generated images
+     * @param size Optional, the size of the images. Defaults to "1024x1024"
+     * @param model Optional, the GPT image model to use. Defaults to "gpt-image-1-mini"
+     * @returns A Promise that resolves to an array of PNG data URLs for the generated images
      */
-    public async generateImages(prompt: string, numberOfImages: 1 | 2 | 3 | 4 | 5, size: ImageSize = "512x512", model: Model = "dall-e-3"): Promise<string[]> {
+    public async generateImages(prompt: string, numberOfImages: 1 | 2 | 3 | 4 | 5, size: ImageSize = "1024x1024", model: Model = "gpt-image-1-mini"): Promise<string[]> {
+        const outputFormat = "png" as const;
         const response = await this.openai.images.generate({
             model,
             prompt,
             n: numberOfImages,
             size,
+            output_format: outputFormat,
         });
 
         const { data } = response;
+        const mimeType = `image/${outputFormat}`;
 
         this.logger.log("Got image!", data);
 
@@ -55,11 +59,13 @@ export class ImageGenerator {
         const imageUrls = new Array<string>(numberOfImages);
 
         for (let i = 0; i < data.length; i++) {
-            const url = data[i]?.url;
-            if (!url) {
-                throw new Error("Image URL is null");
+            const imageData = data[i];
+            const base64 = imageData?.b64_json;
+            if (!base64) {
+                throw new Error("Image data is missing");
             }
-            imageUrls[i] = url;
+
+            imageUrls[i] = `data:${mimeType};base64,${base64}`;
         }
 
         return imageUrls;

src/index.ts

@@ -12,8 +12,8 @@ export type StoryPayload = {
     content: string;
     /** Temperature used to generate the story */
     temperature: number;
-    /** URL for the story image. 
-     * This link expires so be sure to download it */
+    /** Image data URL for the story image. 
+     * For GPT image models, this is a base64 data URL. */
     image: string;
 }
 

src/story.ts

@@ -82,14 +82,14 @@ export class Story {
     }
 
     /**
-     * Generates an image for the story using DALL-E
+     * Generates an image for the story using OpenAI's GPT image models
      * @param size Optional, the size of the image. Defaults to "1024x1024"
-     * @param model Optional, the DALL-E model to use. Defaults to "dall-e-3"
-     * @returns A Promise that resolves to the URL of the generated image
+     * @param model Optional, the GPT image model to use. Defaults to "gpt-image-1-mini"
+     * @returns A Promise that resolves to the data URL of the generated image
      */
-    async generateImage(size: ImageSize = "1024x1024", model: Model = "dall-e-3"): Promise<string> {
+    async generateImage(size: ImageSize = "1024x1024", model: Model = "gpt-image-1-mini"): Promise<string> {
         this.logger.log("Generating image prompts");
-        const imgPrompt = "Based on the previous story, write a prompt for an image generation service Dall-E. " +
+        const imgPrompt = "Based on the previous story, write a prompt for an OpenAI image generation model. " +
             "Keep the prompt detailed and tell the system to use a particular art style referring to a particular artist/painter. " +
             "Make the prompt be less than 400 characters. " +
             "Respond only with the prompt. No other text is needed.";