🧠✨ Testing GPT-4o’s Image Generation – From C# with ❤️ and Microsoft.Extensions.AI

Hi!

OpenAI just dropped some exciting news:
👉 GPT-4o can now generate images directly from prompts.
Announced here: Introducing GPT-4o Image Generation, this new feature lets you go from words to stunning visuals – including photorealistic scenes, illustrations, logos, and more.

The fun part? You can now generate images just by chatting with GPT-4o.

The challenging part? If you’re a developer trying this via the OpenAI API… it’s not quite ready yet 😅

🎯 My Test: “Make Me a Cute Sticker”

So, naturally, I tried this in ChatGPT — and it worked beautifully.
Just uploaded a photo of my cat, added this prompt:

“Make me a cute minimalist sticker based on the provided image. Use a thick white border and transparent background.”

Boom 🐾 — instant sticker! Minimalist lines, clear cat expression, perfect for printing or slapping on your laptop.

🔧 Now Let’s Try in C# (Spoiler: it’s not ready… yet)

Being a .NET fanboy and AI tinkerer, I fired up a quick console app using the awesome new Microsoft.Extensions.AI library — designed to unify and simplify AI model calls from .NET.

Here’s my code using the OpenAIClient with GPT-4o:

	using Microsoft.Extensions.AI;
	using Microsoft.Extensions.Configuration;
	using OpenAI;
	using System.Reflection;

	// 1. get the image
	var imageLocation = Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), "images", "petsmusic.png");
	var mediaType = GetMediaType(imageLocation);
	byte[] imageBytes = File.ReadAllBytes(imageLocation);

	// 2. prep openai client using gpt-4o
	var imageGenPrompt = $"make me a cute minimalist sticker based on the provided image. use a thick white border and transparent background.";
	var config = new ConfigurationBuilder().AddUserSecrets<Program>().Build();
	IChatClient chatClient = new OpenAIClient(config["OPENAI_APIKEY"]).AsChatClient("gpt-4o");
	List<ChatMessage> messages =
	[
	new ChatMessage(ChatRole.User, imageGenPrompt),
	new ChatMessage(ChatRole.User, [new DataContent(imageBytes, mediaType)]),
	];

	// 3 run image generation
	var imageAnalysis = await chatClient.GetResponseAsync(messages);
	Console.WriteLine($"Prompt: {imageGenPrompt}");
	Console.WriteLine();
	Console.WriteLine($"Response: {imageAnalysis.Text}");
	Console.WriteLine();

	static string GetMediaType(string imageLocation)
	{
	// Logic to determine the media type based on the file extension
	string extension = Path.GetExtension(imageLocation).ToLower();
	return extension switch
	{
	".jpg" or ".jpeg" => "image/jpeg",
	".png" => "image/png",
	".gif" => "image/gif",
	_ => throw new NotSupportedException($"File extension {extension} is not supported"),
	};
	}

view raw ImageGenOpenAIAPITest.cs hosted with ❤ by GitHub

📉 The Actual Output

Here’s what I got back from GPT-4o via API:

Prompt: make me a cute minimalist sticker based on the provided image...

Response:
To create a cute minimalist sticker from the provided image, follow these steps:
1. Crop and Simplify...
2. Add a thick white border...
3. Use a transparent background...

You can use tools like Adobe Illustrator or Canva.

Basically — the model understood the task, but instead of returning a new image, it gave instructions 📄.

❗ Why the Disconnect?

The image generation capability is live in ChatGPT, but not yet exposed via the OpenAI API.
As of now:

GetResponseAsync() from Microsoft.Extensions.AI supports image inputs ✅
But image generation as an output is not yet supported ❌

So developers: sit tight, it’s coming.

💡 Takeaways

GPT-4o’s new image generation is 🔥 — in ChatGPT.
If you’re building with .NET and Microsoft.Extensions.AI, you’re already in a great spot to tap into these APIs as soon as image outputs are supported.
Until then, your code can analyze and interpret images with GPT-4o, but it can’t yet generate them.

👀 What’s Next?

I’m keeping this code snippet ready for when OpenAI opens up the feature.
And I’m already thinking about using this in:

Sticker generators 🐱
Avatar creators 🧙
Meme bots 🤖
Or even something weird, like “What if your plant could draw?”

Let me know if you want to explore this together — or if you’re building cool stuff with GPT-4o and .NET.

Until then, happy coding!

— Bruno 💬🐾

2 responses to “🧠✨ Testing GPT-4o’s Image Generation – From C# with ❤️ and Microsoft.Extensions.AI”

Dew Drop – March 31, 2025 (#4393) – Morning Dew by Alvin Ashcraft

Mar 31, 2025 7:57 AM

[…] 🧠✨ Testing GPT-4o’s Image Generation – From C# with ❤️ and Microsoft.Extensions.AI (Bruno Capuano) […]

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뉴테크프라임 » My AI Smarteasy 사용자 정의 코파일럿 에이전트 – GPT-4o 이미지 생성, 무엇이 달라졌을까?

Aug 9, 2025 3:24 AM

[…] Testing GPT-4o’s Image Generation – From C# with … – El Bruno […]

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